List of Accepted Papers (ICMIEE 2022)
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Abstract
Phase Change Materials (PCM) find wide applications for transient thermal control in several industry sectors, such as reducing cost of energy to maintain thermal comfort in occupied space, transportation of blood, tissue, and organs, increasing the reliability of electronic devices, power systems, and weapons used in warfare, and for renewable power generation. Use of contained phase change materials (PCM) for this purpose is a simple, but quite effective and low-cost technical solution. PCM changes from solid to liquid in an endothermic process by absorbing heat, and the liquid to solid phase change occurs when the phase change material releases heat in an exothermic process. The presentation will discuss the state-of-the-art of phase change materials for buildings applications and the limitations of incorporating phase change materials. The challenges include supercooling, low thermal conductivity, phase segregation, fire safety, corrosion, and cost. This study explored how some of these issues can be limited or eliminated. The energy consumption in residential buildings is mostly associated with the heating and cooling load of the interior environment. The application of phase change materials has been demonstrated as a solution to decrease the energy consumption of an apartment building for both heating and cooling
Abstract
Exploiting hydro resources for power generation in Central Southern Himalayan region encompassing Nepal, Bhutan, India, and China require constructing dams and storages in the Ganges and Brahmaputra River systems. Hydropower is not the main portfolio of power in India and China, but Bhutan and Nepal are generating almost 100% of their electric power from hydro resources. The generated hydropower not only meets the power needs of these two countries but also, they export the surplus power to neighbouring country. Currently Bhutan generates 4 times more hydropower than its needs. A similar mega plan is underway in Nepal. The Ganges and Brahmaputra River flow is the collection of pulses and not a uniform flow of water that change during the day and year feeding continuously and sustainably millions of years developed upstream and downstream ecosystem as well as human water consumption, food production and transport. To achieve a reliable electric power supply, engineers smooth out the river pulses by constructing thousands of water storages and dams in Central Southern Himalayan region to suit continuous power generation demand thereby making the Ganges and Brahmaputra River ecosystems as water pipes. These artificial changes and obstructions will have irreversible impact on these two important river ecosystems on which the livelihood of over 600 million people depends. This paper highlights the needs for amalgamated approach involving expertise from engineers, hydrologists, economists, environmentalists, ecologists, and most importantly the traditional beneficiaries from upper, middle, and lower riparian nations for undertaking a comprehensive river ecosystem management plan, implementation, monitoring, continuous assessment, and corrective measures collectively. Additionally, the paper discusses the need for utilization of indigenous hydro resources for power generation that can be used beyond the national boundary in South Asia to enhance the collective energy security for economic prosperity and social development.
Abstract
As the smaller and faster-based current trend of technological development leads to dramatic increase in the power densities and heat flux in modern devices and systems, it’s more challenging to meet their thermal management demands than ever. Smart and innovative thermal solutions and technologies are thus urgently needed to tackle such increasing challenges for the thermal management of many important sectors such as electrical vehicles, microelectronics, power electronics equipment and energy systems. Here comes the novel nanofluids, the suspension of nanoscale particles in heat transfer fluid, which show great potential to meet such thermal management and energy performance demands. Having substantially increased thermophysical properties and features, the impact of nanofluids technology is great considering that the thermal performance of heat exchangers or other systems, processes is vital for numerous industries. For instance, the potential estimated world-wide market for nanofluids only in heat transfer applications is a few billion dollars per year and it is expected to grow further and rapidly over the next several years or decade. Given the surge of research interests and activities as well as the enormous potential, this keynote first provides background of nanofluids and a critical appraisal on their performance in thermal management for their advanced applications. Subsequently, their roles and prospects in the energy sector particularly in solar energy utilization and conversion are discussed. Finally, this speech answers the key question poised here- is this new class of fluids capable of meeting modern thermal management and energy challenges.
Causes of Chatter Formation in Metal Cutting and Innovative Chatter Control Strategies
Abstract
The paper will highlight the contribution of the manufacturing sector in the overall economy of major developed and some developing countries. In the broader concept of manufacturing the position and role of metal cutting and machining will be highlighted. The major challenge towards achieving high precision, good product quality and productivity will be addressed. Chatter, a self-excited vibration in machining process, with its adverse effects will be introduced. The existing theories on chatter problem will be summarized and the concept of Resonance theory of chatter will be introduced. The works of the author on understanding the causes of chatter formation in turning and in end milling will be briefly discussed to explain the justification for proposing the Chatter Resonance Theory of Chatter. Basic concepts of the Resonance theory will be presented. Different Chatter control strategies developed by the author and his students with their effectiveness in controlling chatter will be illustrated in brief. Finally, the contribution of the school of the author towards understanding the complex phenomenon of chatter in machining through research and publication and innovation will be summarized.
Condensate Characterization: An Approach to Evaluate the Performance of Condensate as a Feedstock in Oil Refinery
Abstract
Crude oil or petroleum fractions, a complex mixture of large numbers of hydrocarbon components produce petroleum streams during the distillation. Physical properties of the refining feedstock, also known as assay information, are mandatory for an efficient process and engineering design of a refinery; however, the complete compositional analysis of naturally occurring hydrocarbon mixtures is complicated and time-consuming. This paper aims to develop an approach to a systemic and organized characterization of gas condensate as refining feedstock to generate assay data based both on laboratory experiments and software-aided analysis. The study, moreover, focuses on the critical analysis of the assay information of the gas condensate samples, which are collected from the Rashidpur (RGF) and Kailashtila (KTL) gas fields, Bangladesh. Initially, the study conducted laboratory experiments to determine the boiling point and specific gravity. Required physical properties for refining process calculations are determined by empirical correlations. Riazi and Daubert?s model and Daubert?s new method, construct the true boiling point (TBP) curve, and the extrapolation of the Daubert curves gives the ultimate recovery at the final distillation point. Subsequently, DWSIM software, using the thermodynamic model of Peng Robinson, assists the generation of pseudo-components and their properties based on the engendered TBP data. The findings of this research aid the proper and correct identification of critical physical parameters to use the accepted existing industrial packages in the refinery. It can additionally serve as a platform to evaluate the performance of condensate as a refining feed stoke
Investigation of Chloride Removal from Soaking Wastewater by Using Natural Biomass
Abstract
Soaking is the first beamhouse operation, where preserved hide/skin is rehydrated to make them flaccid, removal of dirt, and curing salt. The emitted soaking wastewater contains an enormous amount of dissolved solids. Common salt (NaCl) is mostly used for the preservation of hide/skin from which the primary pollutant chloride is emitted in the effluent. Due to its high dissolving capacity and non-biodegradability, chloride is difficult to remove. It has a detrimental effect on both aquatic and terrestrial ecosystems. Acute exposures to high levels of chloride have also been associated with diseases of the lower airways and interstitial lung. In this investigation, natural biosorbent Tamarindus indica leaf biomass was used to adsorb chloride from tannery-soaking wastewater. Batch-wise chloride adsorption from the soaking wastewater was performed considering different parameters-biomass dose, pH, and contact time. The biomass was characterized by the Fourier Transform Infrared (FT-IR) spectrum. The pseudo-second-order kinetics model was fitted to the chloride adsorption. The chloride content in the soaking wastewater before and after treatment was 18970.9 and 6306.9 mg/L, respectively. This treatment technique also reduced the pollution load: chloride, chemical oxygen demand (COD), biochemical oxygen demand (BOD), total dissolved solids (TDS), and electrical conductivity (EC) 66.8%, 44.07%, 39.57%, 29.63%, and 23.65%, accordingly from soaking wastewater. This investigation demonstrated the remarkable potential of Tamarindus indica leaf biomass to remove chloride from the soaking wastewater.
Abstract
In leather manufacturing, retanning is a process that is directed to improve the roundness, fullness, softness, grain firmness, filling, and suppleness of the final leather. In retanning, mostly resin, syntan, and vegetable tannins are used. Usually, vegetable tannins are selected for retanning because they are natural, non-toxic, biodegradable, and economical. Vegetable tanning agents are rich in polyphenols which are cross-linked via hydrogen bonding with collagen protein. In this study, waste date seeds are used as an alternative source of vegetable retanning agents in leather processing. Date seeds contain polyphenols and flavonoids that are generally discharged as waste. The waste date seeds were collected, washed with distilled water, sun-dried, and oven-dried at 105°C for 24 hours. The dried date seeds were ground by a laboratory crusher. The Soxhlet extractor was used to extract tannin in ethanol as a solvent. The extracted tannin was characterized by Fourier Transform Infrared (FTIR) Spectroscopy. For retanning, tannins were extracted in water from date seeds ground at an optimized temperature (55°C) by a water bath. At the optimum temperature (55°C) tannin extraction was 3.29%. The tannin extracted in water was used in the retanning process for leather manufacturing. The physical properties e.g., tensile strength, percentage of elongation, stitch tear strength, and shrinkage temperature of the produced leather were 296.01 kg/cm2, 48.8%, 141.5 kg/cm, and 124.4°C, respectively. The experimental leather showed better results compared to the conventional leather. This study indicates a new source of retanning agents, which is economical, feasible, and eco-friendly.
Dye removal from tannery wastewater by adsorption-coagulation using Moringa oleifera bark charcoal
Abstract
In the tannery, dyeing is an essential post-tanning operation where coloring substances are applied to make the leather attractive and adaptable for fashion styles. The dyestuffs used in leather processing vary depending on the product range required along with the states of the emerging market. Mostly, acid dye is used in the leather industry. After dye fixation, a good fraction of dye remains unfixed that has to be rinsed out to prevent dye transfer from the leather. The released dyeing wastewater into the environment makes the effluent highly colored, increases biochemical oxygen demand (BOD), and chemical oxygen demand (COD), impairs photosynthesis and inhibits plant growth. Conventional techniques of effluent treatment have failed to provide effective results because of the higher cost and less efficiency. Even biological treatment may not be efficient in dye removal, especially in tannery wastewater because of higher dye concentration. In this investigation, an approach was made to eradicate dye from the tannery wastewater of composite dye with the Moringa oleifera bark charcoal adsorbent. The Moringa oleifera bark was burned in the furnace at 500?C and then batch-wise dye removal from the wastewater was conducted through the adsorption-coagulation process. The charcoal effectiveness for dye removal was analyzed by investigating relative pH, charcoal dose, contact time, dilution factor, isotherm model, and adsorption kinetics. Before and after use, Fourier Transform Infrared (FT-IR) spectroscopy was performed to differentiate the active components of the surface of the charcoal. The FT-IR spectrum indicated the shifting in bonds of the functional groups because of the dye adsorption. At optimal conditions, the dye removal efficiency was obtained at 81.9%. The use of native Moringa oleifera bark charcoal adsorbent could be a choice to remove dye from industrial tannery wastewater.
Short-Term Preservation of Goatskin with Antioxidant Containing Banana Peel Paste
Abstract
The main raw material for the leather business is unprocessed hide and skin, which is leftover in the slaughterhouses. To stop bacterial action after flaying, the raw hide and skin must be preserved right away. Commonly sodium chloride is used to preserve the hides and skins, which has a significant influence on the increment of the total dissolved solids (TDS) and salinity in the groundwater and surface water as well. Therefore, the wet salting method is detrimental to humans, plants, and animals. To lower the pollutant load in a soaking operation, this research focuses on antioxidant-containing short-term preservation of goatskin using Musa acuminata (banana peel) paste. Freshly flayed goatskins were preserved by using banana peel paste on a laboratory scale for 12 days and monitoring the hydrothermal stability, moisture content, odour, physical feel, and hair slip regularly. After the 12th day of preservation, chloride, total dissolved solids (TDS), biological oxygen demand (BOD), and chemical oxygen demand (COD) were used to assess the physicochemical properties of soaking wastewater. Compare to the conventional method, total dissolved solids, chloride, biochemical oxygen demand, and chemical oxygen demand are the pollutants that are reduced by the suggested technique by 23.3%, 50.02%, 57.14%, and 33.33% respectively. The findings of this study recommend that salt-free utilizing Musa acuminata paste could be an alternative way to preserve goatskin by reducing the pollution load in the soaking wastewater.
Analysis of Microstructure and Mechanical Behavior of Zamak 2 Alloy on Precipitation Hardening.
Abstract
Zinc alloys contain significant qualities that make them appropriate for industrial usage, such as a low melting point, nontoxicity, and high corrosion resistance. Zamak alloys are zinc casting alloys with exceptional fluidity and formability during the casting process. Zamak 2 alloy has 3.9 percent aluminum, 2.9 percent copper, and the rest zinc. It offers exceptional mechanical qualities, including as high tensile strength, creep resistance, and hardness. The presence of copper in this alloy causes the precipitate (CuZn4) phase to form, which improves mechanical qualities. However, more than 1.25 wt.% copper causes dimensional instability, which can be reduced by heat treatment. The main focus of this experimental report was on precipitation hardening and a comparison of characteristics with a cast sample. This technique achieves strengthening by generating particle dispersion, which acts as a barrier to dislocation movement. The magnitude of strengthening is determined by the interaction between dispersion particles and dislocations. Precipitation hardening was done in two stages: first, the alloy was heated to a high temperature and became liquid, then it was cooled and heated to a slightly higher temperature to achieve homogeneous phase dispersion. The goal of this experiment is to try out different casting procedures, as well as investigate the micro-structural analyses and mechanical qualities of the casting products. Furthermore, the effect of Cu doping on the Zamak 2 alloys was observed using precipitation hardening. Simultaneously, the micro-structural changes and mechanical characteristics augmentation of Cu doped alloys were compared to the non-heat treated alloy. Micro-structural variations and mechanical characteristics were considerably altered during precipitation hardening.
Effects of Impinging Distance, Reynolds Number, and Swirl on the Flow and Heat Transfer Behaviors of Arrays of Circular Impinging Jets: A Numerical Approach
Abstract
Impinging air jets have enormous applications in heating and cooling industries, such as turbine blades electrical equipment, etc. Heat transfer under impinging jet is generally superior to conventional methods since the fluid flow in the form of jet impingement drastically increases its momentum. The interaction between the multiple jet arrangement and low to high swirl intensity warrants extensive research to achieve uniform heat transfer. This study examines both the inline and staggered arrangements of numerous round swirling air jets impinging vertically on a flat surface. In this regard, three-dimensional simulations are executed using the finite volume method for a number of control parameters such as Reynolds number (Re = 11600, 24600, and 35000), impingement distance (H/D = 1, 2, 3 and 4) and jet-to-jet spacing (Z/D = 1.5 and 3.0), while, D is considered as the diameter of the nozzles. The nozzles are arranged in both inline and staggered conditions to obtain the most effective heat transfer. The pressure distribution, wall temperature, and Nusselt number are investigated for different operating conditions. It is observed that the staggered array of nozzle arrangement shows better heat transfer performance than the inline arrangement. Moreover, the thermal performance increases with the Reynolds number and swirl number since the fluid velocity as well as heat transfer rate increase due to turbulence. Besides, higher spacing between neighboring jets secures greater cooling areas on the impinging plate and accelerates the procedure to gain better uniformity in cooling effect. However, the thermal performance compromises with increasing impingement distance since much interaction time are involved in case of higher traveling distance.
Analysis of LOCA in Cold Leg and Risk Evaluation of Pressurized Water Reactor based NPP
Abstract
Transient response of a Pressured Water Reactor (PWR) based nuclear power plant parameters and safety systems during a Loss of Coolant Accident (LOCA) for cold leg has been carried out by using PCTRAN and COMSOL. The whole study is done with a consideration of Nuclear Power Plant (NPP) with two loops of a PWR. The plant model used in this work is a generic two loop with inverted u bend steam generator and dry containment system with a thermal output of 1800 MWt. The simulation result of this entire study is conducted by PCTRAN software, COMSOL Multiphysics software and Fuzzy Expert System (FES) installed in Nuclear Engineering Laboratory at MIST. PCTRAN results show that the Loss of Coolant Accident (LOCA) has caused a rapid drop in coolant pressure while the turbine trip accident has showed a rapid drop in total plant power. Few neutronics parameters have been studied using PCTRAN, thermal behavior during Cold LOCA has been studied using COMSOL, and finally accident prediction has been simulated using FES. The results obtained from the study are compared for getting a precise and accurate result. All the rated parameters regarding this type of reactor are set as default. The main focus of this work is comparing the behavior of some important parameters in case of selected two accidents which are basically design basis accidents (DBAs) and the plant is capable to withstand such accident to a certain level varying the type of situations.
A Simple Approach to Potential Application of Vegetable Tanning Techniques by the Indigenous Bovine Fat and Notholithocarpus densiflorus Extract
Abstract
It is the first time, indigenous bovine fat have been introduced in vegetable tanning process to produce the water resistance vegetable tanned leather. The bark and wood has been collected from the Tanoak tree (Notholithocarpus densiflorus) abundant in leather institute, Dhaka University and bovine fat has collected from the local market Hazaribagh, Dhaka, Bangladesh. The vegetable tanning extract and modified indigenous bovine fat have been used in tanning process together as stuffing techniques for water resistance leather. Lower acid value, lower iodine value and high saponification value have been found in satisfactory level of bovine fat and this the best qualifications for using in water resistance leather. The Tanoak extract was systematically analyzed and found mainly two types of tannin mainly catechol in bark and pyrogallol in wood. Resultant bark and wood extract tanning-leather have been tested by the Society of Leather Technologists and Chemists (SLC) official analysis method. The tensile strength, stitch tear strength, water resistance, waterproofness, grain crack resistance, flexing endurance, softness etc. have been found in satisfactory level. This new kinds of water-resistance vegetable tanning process will help to replace the chromium tanning, sustainable tanning approach, save the environment and to earn more foreign currency.
Study of the Effect of Releasing LPG in the Environment with Different Wind Velocity Using ALOHA
Abstract
LPG gas is one of the chemicals with a high potential for harm to the environment which is now widely used in industry and other purposes. In this study, the ALOHA model has been used with the consideration of different wind speeds to evaluate the impact of releasing LPG to the environment which causes harmful effect on human health. The purpose of this study is to show the toxic and flammable area of the affected area from the released LPG vapor cloud. The red zone (AEGL-3) of the toxic and flammable vapor cloud from the released gas remains constant with increasing ambient wind velocity for each LPG property (propane (C3H8), butane (C4H10), and isobutene (C4H10)). On the other hand, the orange zone (AEGL-2) is a little bit decreasing with increasing wind speed. But yellow zone (AEGL-1) is more decreasing than the red zone (AEGL-3) and orange zone (AEGL-2). The flammable area of the isobutene (C4H10) is more decreased than the propane (C3H8) and butane (C4H10). This study may be considered for future risk assessment in the LPG plants with varied ambient wind speeds for minimizing the potential impact of LPG release.
Abstract
We are using fossil fuels which has recognized as a major cause of climate change but after some year fossil fuels will be overed. So we need to turn increasingly to alternative energy source as an answer to the economical, environmental and social problems links to fossil fuel use. Alternative energy resources are broadly defined as energy source that do not cross the limit of net emission of carbon dioxide and avoid atmospheric impacts. . We are using fossil fuels which has recognized as a major cause of climate change but after some year fossil fuels will over. The most common activity in our day to day life is walking. While walking, the person loses energy to the surface in the form of tremble. This energy can be tapped and transmuted to electrical form. In this project, we aim to design and test a simple device which converts the kinetic energy of footsteps into electrical energy. The device was efficiently designed, fabricated and tested. The objectives of my project are design of a staircase to produce electricity from footsteps, fabrication of the designed staircase and analysis of the system for better performance. The vitality can be used by simply setting a unit "Stride Power Generation System". By putting the framework in a country building or in spots like railroad station, so much vitality can be caught. This devoured vitality can be utilized for the lights on the rustic territory or the packed spots like railroad stations, universities and so forth.
Abstract
Metallic foams have drawn significant attraction nowadays for their excellent physical, mechanical, thermal, electrical and acoustic properties with a lightweight structure. Magnesium oxide foams are widely used in automotive industries, biomedical applications, aerospace and other industries due to the properties of low density, higher strength to weight ratio, wear resistant, ductility, and adsorption. In this thesis report fabrication of magnesium oxide foam by space holder technique via powder metallurgy route is discussed. Here, ammonium hydrogen carbonate has been used as a space holder. After mixing the powders by different ratios by ball milling, uniaxial compaction of the mixture has been done in die punch under a pressure of 30 kN. The sintering is done at 1475°C for 6 hours. Through obtaining data after sintering the density and porosity have been measured and is seen to vary from 1.56 g/cc to 1.16 g/cc in density and 8.77% to 25.64% in porosity with the increase of space holder. The compressive stress is seen to vary from 197.6 MPa to 94.3 MPa with the decrease of the space holder.
DESIGN AND ERECTION OF SEVERAL STOCKPILE SORTING SYSTEM BASED ON RADIO FREQUENCY IDENTIFICATION (RFID)
Abstract
Automated sort-based machines can consistently run up to the same value of at the same repetitive pace, reducing the chance of injury or, worse, an accident. To automate inventory placement tasks, Radio Frequency Identification (RFID) technology is used to identify, store, collect, and transmit . The proposed system can uniquely identify material and equipment types and facilitate cost-effective solutions for tracking them almost instantly. Today, increasing the attributes and reliability of products and services is a must for all manufacturers. Automated sorting systems play an essential role in ensuring that goods and products are properly organized and distributed across different industries. Producers now understand the benefits of agility, accuracy and capacity Bring an automated sorter to the production line.
Numerical Investigation of the effect of different Aerofoil profile of a spoiler in a car
Abstract
ABSTRACT With the changes in speed, aerodynamic vehicles experience issues such as unstability, excessive fuel consumption, and increased drag and lift forces and so on. A great amount of lift force is created at the back end of the vehicle when a person drives a vehicle at a high speed, which can be reduced by attaching a spoiler at the rear side of the car. Spoiler is an aerodynamic device that is designed to improve lift and drag force in high velocity conditions by spoiling adverse air movement. This paper shows the influence of the rear spoiler in an aerodynamic vehicle and the changes that occur when a rear spoiler is adjusted. The right height of the rear spoiler from the rear trunk at a constant high speed and constant angle of attack is being investigated here. To obtain those results, 2 symmetric and 1cambered (total 3) type NACA Aerofoil is being analyzed as a rear spoiler with the help of CFD. ?CFD (Computational Fluid Dynamics) is a set of numerical algorithms used to estimate the solution of fluid dynamics and heat transport issues." In today's fluid dynamics research, CFD is a useful instrument. It brings together fluid mechanics, mathematics, and computer science.CFD has the advantage of creating a virtual prototype of a system?s physical, chemical and thermal characteristics. Visualizing the virtual prototype?s projected behavior can reveal details about the design that would otherwise be impossible to see. BMW 3 series car model is used here which is being modeled in solidworks19 and then imported in ANSYS Fluent (2020R2). To numerically simulate the external flow field of the simplified Sedan type model with or without a rear spoiler, the k-omega SST turbulence model was chosen. A new rear spoiler is utilized as a consequence of an examination of the simulation results, which demonstrates a slight reduction of the vehicle aerodynamics lift force with the optimization of lift and drag force. Among the three types of naca profile, it can be seen that NACA 0012 provides more down force (38%) than other two types NACA 0012 (37.8%) and NACA 2412 (32.5%) when they are used as a rear spoiler in a car 2.68??10?^6. Despite the fact that spoilers are often attached to a vehicle to minimize lift force, they actually increase drag force in this case, as seen in this research. From a safety standpoint, reducing aerodynamic lift is more critical than reducing aerodynamic drag. At Reynolds number 2.68??10?^6 NACA 0012 increases drag force 12.8%, NACA 0018 increases drag force 8.67 %, and NACA 2412 increases drag force 12.3%. The best height of the spoiler from the rear tank is 0.4 times than distance between the rear trunk and the upper surface of the car body in which more amount down force generated. Key Words: Spoiler, CFD Analysis, NACA profile, Down force
Abstract
Animal skin is basically a protein structure inside that can be stable through some crosslinking agent that can make it durable, and imputrescible with excellent properties and transform it into leather. In recent studies, tanning with unnatural amino acids like D-Lysine or D-Arginine combined with some aldehyde such as glutaraldehyde gives a direction towards implementing protein crosslinking reactions in leather tanning with dialdehyde. Usually, Maillard reaction happens in human body between collagen and three carbon methylglyoxal that generates from six carbon sugar. From that thought, we tried to carry out the Maillard reaction of protein crosslinking between the amino group of amino acids and carbonyl groups of sugars that leads to the crosslinking agent methylglyoxal. We designed the recipe for tanning from previous acquisitions and faced some complications in pH range for penetrating and fixing the chemicals to the collagen. Several re-tests were performed to validate the measurements of thermal stability change of the pelt. Finding the optimum activity condition for the collagen and chemicals might lead us to an eco-friendly method to leather tanning process. In that case, we were trying to find the optimum condition and interactive behavior of amino acids and methylglyoxal with collagen. The crosslinking activity of the methylglyoxal with amino acids and collagen in various pH ranges have been investigated to check the physiochemical properties of leather with respect to hydrothermal stability. The shrinkage temperature was determined after each re tests with shrinkage tester, which indicates the variation of outcomes with the variation of pH. The approach to do the crosslinking between dialdehyde and amino acid first and penetrating to leather also gave fluctuation in result with pH. In all the cases, we could not find our desired shrinkage temperature. In one case, to tan at pH 3.5 and fixation at 4.5, the shrinkage temperature was found above 70 degrees Celsius, but in other pH ranges, shrinkage temperature was below 70 degrees Celsius. The concept to make crosslink between chemical first and then adding it to a tanned bath, the shrinkage temperature was still below 70 degrees Celsius. The whole work gives the insight of two statements. Either the crosslinking with methyglyoxal like Maillard reaction is not possible in leather, as methylglyoxal doesn't have much tanning power on its own, or there might be some intertwining required to get the expected result. The activity of amino acid was checked by ninhydrin test and the activity of carbonyl group of methylglyoxal also checked. The outcome of our work indicate that the prospective shrinkage temperature is not possible with methylglyoxal and amino acid tanning, but there might be a good chance of getting positive output using glyoxal as a cross linker dialdehyde. As a result, shoe-upper leather cannot be produced if we use tanning chemicals methylglyoxal and amino acid. Methylgyoxal solo tanning produced shrinkage temperature up to 50 degrees Celsius, but combining with amino acid showed result up to 70 degrees before fixation process. There is still an immense possibility to find shrinkage in higher extent in final leather if glyoxal is used instead methylglyoxal. There might be some barrier or twisting holding us from finding a new era of leather science
Effect of Exhaust Gas Recirculation on Combustion and Emission Performance of a Dual Fuel CI Engine ? A Numerical Investigation
Abstract
Due to the depletion of Diesel fuel and higher cost, it is desirable to find alternative fuel with lower cost and better combustion and emission characteristics. As, gaseous fuel is cheaper than liquid fuel, one of the effective solutions to obtain better engine performance is replacing a portion of liquid fuel by gaseous fuel in CI engine which is called dual fuel CI engine. In dual fuel engine, main gaseous fuel is provided through intake manifold by premixing with air and the mixture is ignited by injecting liquid pilot fuel at near the end of the compression stroke. The process is cost effective as well as the engine obtain higher thermal efficiency and lower soot, CO, UHC emission. But NOx emission is increased in CI engine with dual fuel mode which adversely affected the human health and pollute the environment. By applying Exhaust Gas Recirculation (EGR), NOx emission and knocking of the engine can be reduced. In this numerical simulation, the effect of EGR on combustion and emission performance of dual fuel CI is investigated through ANSYS Forte 18.1. In this study, gasoline is considered as main gaseous fuel and diesel is considered as liquid pilot fuel. Effect of EGR on various engine parameters such as in-cylinder pressure, temperature, heat release rate, ignition delay, combustion duration, NOx, CO and UHC emission is investigated. It is seen that, in-cylinder peak pressure is reduced to 50.65% and in-cylinder maximum temperature is reduced to 60.19% for the addition of 40% EGR. NOx emission is reduced to 57.19% for the addition of 10% EGR, 21.32% for 20% EGR, 1.57% for 30% EGR and 0.014% for 40% EGR.
Preparation and Characterization of graphene-based keratin nanocomposite as an adsorbent for removal of anionic dye from tannery wastewater.
Abstract
Usable water in the environment is one of the most important natural resources, and anthropogenic contaminants from various sources endanger this usable water. Consequently, extreme tannery dye wastewater is a significant environmental problem due to severe disturbance of aquatic habitat photosynthesis by hampering light penetration into the waterbody. The aim of this study is to fabricate the graphene-keratin nanocomposites for the removal of dye from tannery wastewater. Nanocomposite was prepared using a facile solution casting method and characterized by UV-Vis spectroscopy, and material interactions. The pH effects, adsorbent dosage, and contact time of composite has been studied for process optimization. At pH 8, about 96.3 % dye removal was obtained with 6gL-1 nanocomposite adsorbent within 240 minutes. Prepared nanocomposite treats tannery wastewater utilizing a tannery solid waste as the keratin powder was prepared using waste hair from tannery. It could have industrial application as a cost-effective adsorbent with an easy preparation process for dye removal from tannery wastewater.
Effect of Blockage Area Variation on the Hemodynamic Characteristics in Stenosed Artery using Numerical Techniques
Abstract
The investigation and in-depth study of vascular fluid dynamics play a vital role in the study of how the development of atherosclerosis occurs, one of the most prominent diseases in humans. Recent advances in computational fluid dynamics (CFD) can contribute to monitoring flow in presence of stenosis without in-vivo techniques with sufficient accuracy and less cost. In the present work two-dimensional artery models with single stenosis but with blockage percentages of 35%, 50%, 75%, 80%, 86%, and 95% respectively were taken for carrying out the analysis, a numerical simulation was hence performed to assess the effect on physiological flows. The blood is assumed to be incompressible, homogenous, and non-Newtonian, while the artery is assumed to be fixed and rigid. The continuity, momentum, and standard k-? turbulence equations, as well as the non-Newtonian Carreau model, would describe the flow field in the artery model. Steady-state analysis was carried out for the case since simple instantaneous analysis does not warrant a complex transient flow study. The blood flow in the stenosed artery was simulated in commercially available computational fluid dynamics (CFD) software, ANSYS-Fluent. The velocity profile, wall static pressure, wall shear stress, and turbulence intensity were measured in pre-stenotic, throat, and post-stenotic regions. At the throat, the flow changed rapidly, causing an increase in velocity and wall shear stress (WSS) deviating from the normal artery. The pre stenotic region has a modest increase in shear stress. Shear stress increased dramatically in the proximal stenotic area, whereas it reduced further in the distal stenotic and post stenotic regions. This reduction in shear stress boosts the generation of reactive oxygen species, which in turn boosts LDL oxidation in the intima. The fluctuation of pressure close to the stenosis is fatal, given that the value of it is very high for 95% stenosis. In 35% stenosis, a very little fluctuation of pressure closes to the artery. So, it?s not fatal. In the 50%, the fluctuation is increased but this fluctuation is not that high. Fluctuation became much higher after 75% which is bad for health. In the post stenotic region, the flow is quite turbulent, resulting in the creation of vortices. The results indicated that the blockage caused the development of high velocity and along with the viscosity increase causes high wall shear stress to develop on the wall. Because of the stenosis, the throat section has a significant pressure variation and flow becomes turbulent due to crossing the critical Reynolds number. Turbulence intensity goes past medium turbulence limits for 80% stenosis and more than that. Also, it was found from the investigation that a 75 % blockage is dangerous enough and 80% stenosis can be considered critical. Anything higher than that would cause fatal consequences leading to operation (Open Heart Surgery). This characterization of criticality was performed by studying the turbulence intensity variable of the flowing biofluid (blood). The fluid-structure interactions (FSI) in the model for a more accurate and realistic simulation of the stenosis can be considered however it seems it is not always necessary according to our results. This work can be extended to patient-specific image-based real geometries of stenosis, extracted from patient MRI images.
Performance of a CI Engine Operating in Highly Premixed Late Injection and Low Temperature Combustion Mode to Achieve Cleaner Emission ? A CFD Analysis
Abstract
A comprehensive study on a single-cylinder four-stroke cycle Diesel engine that runs in Highly Premixed Late Injection (HPLI) and Low Temperature Combustion (LTC) modes to achieve a cleaner emission than existing normal diesel combustion has been carried out in this CFD analysis. The impact of Highly Premixed Late Injection and Low Temperature Combustion mode on the engine's performance is also examined. Low Inlet Temperature and varying percentages of cooled Exhaust Gas Recirculation (EGR) technology with Injection Timing Retardation were employed to accomplish HPLI and LTC mode. The program utilized for this investigation was ANSYS FORTE 19.2, which was developed by ANSYS. CHEMKIN, a very efficient and comprehensive pre-defined industry-standard chemical kinetics software, is included with this package. At 323K, 353K, 383K, and 413K, this analysis was carried out at various amounts of EGR ranging from 0% to 60%. The results reveal that as the EGR temperature rises, the heat release rate and ignition delay decrease. With an increase in EGR percentage from 0% to 60%, EINOx was lowered from 77.3 g/kg fuel to 1.99 g/kg fuel burned at 323K temperature. EINOx increased from 10.3 g/kgfuel to 14.7 g/kgfuel for 40% EGR with the increase in EGR Temperature. CO increased from 41.8 g/kgfuel to 385 g/kgfuel for 30% EGR with an increase in EGR Temperature. However, when considering UHC and CO emissions, it has been discovered that the percentage of EGR should not be increased further than 50% to reduce NOx emissions. That will also increase CO and UHC emissions. With a high proportion of EGR (40%) and a low temperature, the results were better.
Characteristics of a Nickel Vanadium redox flow battery based on Comsol
Abstract
The overpotential, dissociation rate, electrode potential distributions and current density are suggested in this study to analyze the Nickel Vanadium Redox Flow Battery (NVRFB). Due to its large capacity and ecofriendly properties, NVRFB may be a viable option in the present state of energy constraint and environmental pollution. Due to their low cost and high energy density, nickel-based flow batteries have gained popularity. In this study, a 2D steady-state model of the NVRFB, which is focused on the battery's operating mechanism, is developed. In the mechanism, concentration fields, dissociation fields, electric fields, and electrochemical reactions are concerned. The Nernst?Planck equation is used to predict the mass movement of solution species. To design the model in COMSOL, bipolar plate is taken into account and equilibrium potential is determined using Nernst equation. Dissociation of ions and current density equation based on Nernst-plank are taken into account to check the conductivity of the battery. To build the model using COMSOL, setting up the essential parameters, global definitions, model input, component and research physics is required. In this model, the boundary conditions of the second current distribution interface and the boundary conditions of the tertiary current distribution interface are constructed. This study demonstrates that the Ni2+/Ni+ and V5+/V4+ ions have a higher rate of dissociation at the membrane and a lower rate at the inlet, where the electrolyte flow velocity is greater; Because the membrane undergoes more oxidation-reduction reactions, the electrolyte flow rate is critical in the redox flow cell; Additionally, we see that when electrode thickness is reduced, current density and electrode potential increase while overpotential decreases; the model's equations are solved using the finite-element method in the COMSOL Multiphysics program. An electrolyte-electrode interface connection is used to simulate the reaction. The dissociation rate indicates that the oxidation-reduction process happens at a lower membrane potential. With compression of electrode the overpotential decreases monotonously. Comparing the thickness reduced from 4 to 2.5 mm, the overpotential also decreased by 4mV. From this, it can be demonstrated that the enhancement in cell performance is mostly applicable to the decrease in ohmic loss induced by electrode compression. As this model is based on the state of charge, the drop of the electrode overpotential means that the performance of the battery is improved, the charging efficiency is improved, and the internal loss is reduced. When the electrode is compressed, the current density decreases, resulting in the reduction of the electrode porosity and the increase of the specific surface area and conductivity. With compression terminal electrode potential decreases and because of the state of the charges the decrease of electrode potential means the battery performance is improved. For the 4 mm electrode, the potential is higher and for 3 mm, it decreases to a lower point. Electrode potential denotes the electron reduction and oxidation rate. As a result, electron transfer rate and current flow increase with compression of the electrode. This simulation model was created to investigate the effects of dissociation rate, electrolyte flow rate, and electrode compression on performance attributes. Based on the dissociation rate of the Nickel Vanadium ions, it can be stated that more potential is required to activate the reactions with higher velocity and less potential is required with lower velocity. More reaction occurs at the membrane when the electrolyte flow rate is optimized. The porosity of the electrode decreases as the surface area, conductivity, and electron transfer rate increase. As ohmic loss decreases and current density increases, the overpotential decreases as well. As porosity decreases, so does the electrode potential over the surface. The oxidation-reduction rate increases as the electrode potential decreases. This signifies the battery's performance has been enhanced.
An intelligent industrial safety and health monitoring system for Industry 4.0
Abstract
Industry 4.0 is the integration of information system along with automation to provide complete control over all industrial operation. Although fully automated industry is the target of industry 4.0, there still a need for human supervision and expert guidance. Many of these industries have various safety standards that must be maintained for the safety of the workers and industry experts. Introduction of covid-19 in the year 2019 have also emphasized the need to use masks in workplace all the time. Other necessities such as helmets are also crucial. As most industries are hazardous at certain stages, we also need to monitor and regulate the environment inside the industrial workplace. Bearing these necessities, we propose an intelligent industrial safety and health monitoring system which is capable of detecting workers with or without helmet/mask in real time and also monitor the environmental conditions inside the industry and issue real time warning for any abnormal conditions.
Abstract
Biomimicry is a discipline that learns from or mimics natural mechanisms to solve human design problems. Simply put, it is a method for replicating natural designs and solving complex issues. Nature-inspired aerodynamic models have always been a part of Aerospace Engineering. The fuselage is one of the parts of an aerodynamic vehicle that plays an important role in flight performance. A sailfish has specific structural features in its body which make it more efficient in swimming through water. According to the National Ocean Service, U.S. Department of Commerce, Sailfish is the fastest fish in the world. No wonder the design and topology of the sailfish body have made its drag coefficient one of the lowest. The features of sailfish are being utilized in a variety of ways, including reshaping hull components and re-designing sails using Sailfish fins. Designers and engineers are continually researching their properties to see if any changes are possible in the conventional designs of various models. The target of the project is, to apply the sailfish structure to a modern aircraft model (taking Airbus320 neo as a reference), then to compare the drag coefficient and drag force of both of the designs, and finally, to find out which model is best for efficient flight. A 2D surface of sailfish was done in SpaceClaim and the simulation was done in ANSYS software. The same method was followed for the Airbus320 neo design, and the modified design. The modified design was changed in the nose region. The meshing of the surfaces was done. Material properties, cell zone conditions, and proper boundary conditions were placed. All designs were simulated under the same conditions. Flow and Pressure distribution contour was done. The results showed a difference in the drag coefficient and forces of the modified designs and the conventional aircraft fuselage model which was selected. The drag force was also changed in the cases of these two. A flow with much smoothness was observed for the modified design of the selected aircraft fuselage model. In the air, rather than in water, the low-velocity zone near the snout is more noticeable or diffused. Near the nose, shows a pretty strong velocity gradient. A fusion design of fuselage was created, combining the morphological qualities of sailfish, which aid in its quick maneuverability, with those of the Airbus A320 neo, which made the aircraft so efficient. It implies that the fuel used in the aircraft will be less than the usual use. And so, the hybrid fuselage was validated to be better than that of the selected conventional aircraft model. Key Words: Biomimicry, Fuselage, Drag Coefficient, Drag Force, Fusion Design.
Investigation on Thermal Hydraulics Characteristics of a Thermosiphon for Efficient Decay Heat Removal
Abstract
Thermosiphon is a mechanical device used for removing heat from a source to the environment without any help of external driven force. It is usually a mechanical device, which has the potential to be used as a passive means of heat transfer mechanism to remove decay heat from the reactor core and spent fuel pool. By investigating the characteristics of the fluid flows in a thermosiphon, we can analyze the heat transfer characteristics of a thermosiphon for decay heat removal. A thermosiphon is used in this study because it reflects the configuration of the primary circuits/loops of a nuclear power plant and our focus is to simulate and analyze the heat transfer and fluid flow characteristics in terms of onsite power failure and normal shutdown for maintenance. In this study a comparison of heat transfer has been shown between an open loop and a closed loop thermosiphon and also a comparison of fluid flow characteristics is determined. Finite Element Method has been used to conduct the study within 300-400K temperature & 40 Pa system pressure. Reynolds Number and Nusselt Number are taken as main parameters. Higher Reynolds and Nusselt Number is found the closed loop thermosiphon than in the open loop which indicates more efficient heat transfer along closed loop thermosiphons. This study could be done using nano fluid (Al2O3) as working fluids for getting accurate results and comparison of thermal performance. An analysis has been carried out to investigate fluid flow characteristics in a thermosiphon. The Navier-Stokes equation which is the basis of Computational Fluid Dynamics (CFD) and the continuity equation have been used as a principle governing equation with a view to conducting the study. ANSYS has been used as a reliable software to experience numerical investigation in the most precise manner.
Abstract
The limited reserves of petroleum based fuels have left mankind in pursuit of alternative to diesel. Researchers have been exploring different sources of alternative fuels such as biodiesel produced from non-edible oil sources such as Karanja, Jatropha accompanied by the alcohol fuels, methanol, ethanol, butanol and propanol [1]. This work has experimentally investigated how biodiesel (Karanja oil methyl ester) can be produced optimizely by varying different factors (Molar weight percent of methanol, Percent NaOH ratio, stirring speed and reaction time) from Karanja (Millettia pinnata) oil and calculating some properties of produced biodiesel. 12 samples were made for 4 factors, each factor was varied thrice. Results showed by using 2%(w/w oil) H2SO4 in esterification highest 87.5% yield was found for 6:1 methanol to oil ratio,1.5% NaOH (w/w oil), 70 minutes of reaction time and 600 rpm of stirring speed in trans-esterification. Temperature was always kept at a range of 55?C to 65?C. After conducting several tests the calorific value of the produced biodiesel was found 30.32 MJ/kg, Flash point and fire point were 67.25?C and 77?C respectively. Kinematic viscosity was found to be 19.28 mm2 /sec
Abstract
The steam turbine is the most ideal of all heat engines and prime movers, and it is widely employed in power plants and other sectors where power is required for process. The study's purpose was to develop a power-generating single-stage reaction steam turbine. Thermal energy was used to power the turbine. The research focuses on turbine component design. The micro turbine concept's design and construction were rigorously limited. Stress loss, performance, and angle characteristics were all considered in the blade design. The overall mean temperature and heat transport, as well as other concepts, were used to construct the casing volume. When calculating the amount of tolerance, the heat distribution on the rotor and stator was taken into account. The turbine setup had been constructed according to plan. There were 14 blades made of aluminum. There had been a couple of complications. Leakage was the most important problem of them. Under these conditions, the designed power and heat rate were never achieved. This research looked into the elements and aspects that reduce the turbine's efficiency.
Numerical Investigation of the Aerodynamic Characteristics of a Train Passing through a Tunnel
Abstract
The limitation of geographical space has been a major concern in Bangladesh. So, tunneling may be a solution for the demand of quality and efficient transport with the increasing population. This technology also plays an important role for noise reduction. So, it is essential to investigate the aerodynamic behavior associated with it, because this structure generates relatively more complex airflow patterns than a train running in an open space. As a result, the force and moments associated with train and tunnel has become an essential concern. This paper emphasizes on study of the aerodynamic behaviors of the air flow around the train and tunnel when a train is located at different position relative to tunnel. Simulations of several position of the train with respect to the tunnel has been performed. The effect of Reynolds number, blockage ratio, several locations of train relative to tunnel, the number of bogies on the coefficient of drag (CD) has been investigated. The effect of positions of the train relative to the tunnel on coefficient of pressure (CP) has also been investigated. These processes involve the utilization of computational fluid dynamics (CFD) by using commercial software ANSYS Fluent. During the solver setup, RNG k-epsilon turbulence model with Standard wall treatment has been utilized and boundary conditions at respective boundary has been properly assigned as per required for this study. From this study, it is observed that the aerodynamic changes are more significant when train passes its tunnel entrance and the train undergoes the maximum value of drag co-efficient (CD) which is around 2.24. The co-efficient of drag (CD) increases with increasing the number of bogies and blockage ratio and decreases with increasing its Reynolds number. The nature co-efficient of pressure (CP) also shows a significant change for different locations of the train.
Simulation of Acoustic Emission Signal and its Verification on a Resonant Sensor
Abstract
Among the dominant non-destructive techniques (NDT), the acoustic emission (AE) technique is commonly used for the dynamic monitoring of the material damage. The AE wave is the transient elastic wave formed due to sudden change of stress inside the material due to deformation and damage. This displacement wave is received by the AE sensor. The AE sensor is usually made of piezoelectric crystals i.e. lead zirconate titanate (PZT). It converts the displacement wave to electrical AE signal. The output signal is visualized by the amplitude (voltage) vs time (second) data in the acquisition device. This signal is used for the characterization of the damage by analyzing various AE parameters. To present a suitable method for developing AE wave numerically and to compare with the prevailing AE generation theories, numerous research is being performed in this sector. In this paper, The AE wave has been generated by a load applied on the surface of an aluminum (A5052) block (500mm ? 250 mm ? 250mm) vertically. The aluminum is considered as the homogenous medium of propagation. The integral solution of the governing equation of wave motion for aluminum has been determined based on Betti?s reciprocity theorem. For a point load on the surface, the expression for a displacement function has been derived. It is the convolution of the response function due a step load and the load function in time domain. The displacement of elastic wave due to point step load on a traction free half surface is known as Lamb?s solution. The different components of the response function are derived from the Lamb?s solution The AE sensor has been attached normal to the aluminum surface. Therefore, the vertical component of the response function has been considered. The P-wave, S wave and Rayleigh wave propagate through the material. These waves have been collected by a resonant AE sensor. The peak sensitivity of the AE sensor has been considered as the transfer function for the conversion of the AE displacement wave to AE electrical signal. The transfer loss of the AE signal has been evaluated based on the acoustic impedance of the materials. By integrating the above factors, the final AE wave amplitude function in voltage has been derived. The simulation of the AE wave has been executed based on this derivation. A model experiment has been performed based on the same input parameters in the simulation. The function generator was used to generate the point load on the aluminum surface. The input load was a burst sine function. A preamplifier has been used to boost the received AE signal. Both the simulated and the experimental AE waves were compared based on AE parametric analysis. The time of arrival (TOA) of the generated wave has been determined by the Akaike?s information criterion (AIC) method. The P wave velocity has been determined from the TOA. The rise time has been calculated to find the Rayleigh wave velocities. Significant characteristics of rise time and maximum amplitude with increment of source to sensor distance have been observed. The attenuation properties of maximum amplitude and the increase of rise time with the increment of source to sensor distance has been evaluated to validate the proposed method.
Abstract
This paper analyzes the Theo Jansen mechanism for providing a walking mechanism in terrain areas where wheel-based vehicular systems are less efficient and sometimes ineffective. This project aims to design a simple four-legged walking bot using the Theo Jansen mechanism and to analyze the mechanism's motion for different lengths of the links. This mechanism uses 11 links of certain length ratios in order to imitate the walking motion of a leg. After analyzing the mechanism, a four-legged robot was designed with two legs on each side of a body connected to motors. The four-legged robot can be used as a simple and cost-efficient replacement for surveying terrain areas replacing wheeled vehicles and drones.
Scattering Directivity Pattern Analysis of Low-frequency Lamb Wave at Sub-surface Damage in CFRP Laminate
Abstract
This study focuses on the scattering characteristics of the low-frequency fundamental anti-symmetric (A0) Lamb wave at a sub-surface defect in CFRP laminates. The variable angular amplitude distribution at the defect is one of the key factors affect damage detection algorithm development, toward unavailability of the analytical model. This article presents the computational study to investigate the scattering behavior of A0-mode Lamb wave at a subsurface defect. Unidirectional, bi-directional and quasi-isotropic CFRP laminates with sub-surface damage of the various dimensions were considered as the specimen. Each layer of the laminate considered as horizontally transversely isotropic (HTI) material. Generation of the geometry and meshing were done in explicit type software LS-DYNA. To generate the subsurface damage, elements are removed from the 3D model. Lamb wave is excited by applying the 30 kHz tone burst nodal displacement at the source. Time dependent out-of-plane displacement from the surface nodes are recorded. Good agreement for phase velocity dispersion characteristics is found between the analytical and computational study. The study depict that the profile of the scattered wave depends on the fiber orientation, ply stacking sequence, and the damage size to wavelength ratio.
Numerical study of Fluid Flow and Heat Transfer Characteristics due to Air Jet Impingement in Food Cooling Process
Abstract
When the temperature of the impinging fluid differs from that of the impingement surface, impingement cooling is extensively used to achieve high heat transfer rates. The surface heat transfer coefficient in impact cooling depends on several impact parameters, namely the design of the nozzle, the geometry of the object to be cooled, the exit distance of the beam from the object body, jet speed and jet limit. Jet impingement is frequently used in a number of industrial settings to achieve high local heat transfer coefficients. This thesis is about the air impingement cooling of hemispherical foodstuff, and it was done using ANSYS Fluent and computational fluid dynamics (CFD). As a Turbulence model, SST k-? was employed. For various Reynolds numbers (23,000?100,000), jet-to-cylinder distances, H/d (2?8), and surface curvature, d/D (0.57?1.14), local Nusselt number distributions over the heated object's surface were examined. The Nusselt number of stagnation increases as the Reynolds number increases, but reduces as the surface curvature increases and h/d has very little significance.
Abstract
- This Robotic Arm is used to amplify the flexibility of workstations by transporting material more efficiently and quickly between worktable, peripheral devices and assembly lines etc. Hydraulic system uses liquid, usually it is oil, to transmit force. It works using same principles as other Mechanical systems and trades force for distance. Nowadays Hydraulic system is used at increasing rate on construction sites and specially, in elevators. These are able to do heavy weight jobs, which is difficult to execute for humans. This scheme interprets a simple approach to demonstrate the principle of hydraulic power by manufacturing and operating a robotic arm model from recycled materials. The arm consists of three links of 13.5 cm, 20 cm and 25 cm as well as the base dim * Abstract ension is 18*16 cm square. The syringe volume is 10 ml with specific diameter. After setting up the syringes with the arm, the tube of 0.75 m length is fixed with the opening of the syringes. By this circular tube, water is passed into syringes and three DOF of the arm is obtained by the hydraulic pressure as control signal. There also have base rotation of 50degree, shoulder rotation of 85 degree and elbow rotation of 70 degree. Finally, hydraulic robotic arm has been designed and fabricated to grip and pick a small weight of 75 gram. Overall, the experiment using cardboard is better and convenient. So, the total angle of rotation for three DOF is increased in the experiment
Heat transfer characteristic analysis of double pipe heat exchanger with a continuous helical baffle by Numerical analysis.
Abstract
In this paper, Three-dimensional computational fluid dynamics (CFD) simulations have been performed to study the annulus side laminar flow distribution, heat transfer characteristic, and pressure drop. This paper shows the effect of Reynolds number (Re), helical pitch, and baffle height on Nusselt number (Nu), heat transfer coefficient, heat transfer rate, effectiveness & pressure drop of a double pipe heat exchanger with or without a continuous helical baffle. There are eight geometry was drawn by the design modeler such as pitch 102 mm, pitch 128mm, pitch 170mm, pitch 210mm, pitch 250mm with the pitch height 5mm & again for the pitch 102mm, spiral height 7mm, height 9mm, height 11mm. The outer diameter of the inner tube & inner diameter of the outer tube is fixed in all cases. The spiral was drawn 250 mm far from the inlet because the flow is fully developed after 250 mm. The inner pipe's outer surface is kept at a constant temperature of 340k. The temperature of the cold fluid is 293K. The outer tube?s outside wall is kept adiabatic. The fully developed laminar flow passes through the annulus side with Reynolds numbers vary 700 to 1500. When the increases the pitch of the helical the heat transfer rate decreases. On the other hand, the heat transfer rate increase while increasing helical height. If the comparison will take place between plain tube and helical tube the 47.6 % heat transfer increases while using helical baffle for the pitch 102 mm & Reynolds number 1500. Again while using pitch 102 mm with a height of 11 mm instead of a plain tube the heat transfer rate increases by 97.28 % for the Reynolds number 1500. When the increases the pitch of the helical the Nusselt decreases. On the other hand, the Nusselt number increase while increasing helical height. If the comparison will take place between plain tube and helical tube the 78.53 % Nusselt number increases while using helical baffle for the pitch 102 mm & Reynolds number 1500. While using pitch 102 mm with a height of 11 mm instead of a plain tube the Nusselt number increases by 133.89 % for the Reynolds number 1500. When the increases the pitch of the helical the heat transfer co-efficient decreases. On the other hand, the heat transfer rate co-efficient while increasing helical height. If the comparison will take place between plain tube and helical tube the 78.5 % heat transfer co-efficient while using helical baffle for the pitch 102 mm & Reynolds number 1500. After all, while using pitch 102 mm with a height of 11 mm instead of a plain tube the heat transfer co-efficient increases 131.4 % for the Reynolds number 1500. When the increases the pitch of the helical the effectiveness decreases. On the other hand, the effectiveness increase while increasing helical height. When the increases the pitch of the helical the pressure drop decreases. On the other hand, the pressure drop increase while increasing helical height. The shape of the helical baffle plays an important role in the annulus side heat transfer and fluid flow performance. To enhance heat transfer performance of the heat exchanger by selecting a better helical pitch & height. So, while using a pitch of 102 mm with a height of 11 mm instead of a height of 9 mm the heat transfer rate, heat transfer coefficient, Nusselt number, and effectiveness slightly increase by 2.55 %, 2.8%, 3.9 %, 1.5% respectively. On the other hand, pressure drop rapidly increases by 20 %. Pressure drop is an important parameter in the design of the heat exchanger because the pressure drop increases the pumping cost will also increase as a result operating costs, the maintenance cost will increases. As a result, the overall performance of the helical baffle with a pitch of 102 mm with a height of 9 mm is the best.
Sulphated Fatliquor Extraction from Nagkesar (Mesua Ferrea) Seed Oil for Leather Processing
Abstract
Fatliquor improves organoleptic and strength properties of leather. Fatliquor prepared from non-edible Mesua ferrea seed oil by sulphation process followed by addition of sodium hydroxide to maintain pH at 5.0 with sulphuric acid. FT-IR analysis confirmed that the strong chemical bonding between oil & sulphonic acid group. Physico-chemical properties of sulphated fatliquor were analyzed and compared with conventional fatliquor. Sulphated Mesua ferrea oil fatliquor revealed to Acid value (35.43), Saponification value (255), Iodine value (76.14), Fatty matter (60.9%), soluble in water (250C), PH :6.1 in 10% solution, stable against salt, tanning and basification agent, odorless and dark brown liquid. Prepared Mesua ferrea seed oil fatliquor is consistent in physico-chemical properties with standard value of fatliquor. As prepared eco-friendly and cost effective fatliquor may reduce dependency on edible oils for conventional fatliquor. Therefore, fatliqour prepared from Mesua ferrea seed oil extracted by Soxhlet extraction could be considered as a substitute for commercial fatliqour in leather processing.
Numerical Analysis of the Aerodynamic Characteristics of NACA 2413 Airfoil.
Abstract
The current investigation primarily focuses on the aerodynamic properties of the NACA-2413 airfoil for various turbulent models such as the Realizable k-? Model, Standard k-? Model, and Shear-Stress Transport (SST) k-? Model. The aerodynamic characteristics such as lift force, drag force, lift-to-drag ratio, and pressure distribution were evaluated using the commercial software ANSYS Fluent 2020R2. Additionally, the investigation has been carried out at various angles of attack for different Reynolds numbers (Re = 7?105, 3?106, and 6?106). In this investigation process, the chosen NACA 2413 airfoil coordinate was created using an online airfoil generator, and the coordinates were then imported to SOLIDWORK 2018 to create the desired geometry, and then this geometry was imported to the ANSYS design module. A computational domain was created around the NACA 2413 airfoil for carrying out the simulation. First of all, the chord length of the NACA 2413 airfoil was taken to be equal to 1000mm. From the trailing edge, the domain was expanded 12.5c upstream and 20c downstream, where c indicated the chord length. For the current evaluation, a structured C-type mesh was generated using ANSYS Mesher 2020R2 software. The numerical results indicated that the lift and drag coefficients increased with the angle of attack up to the stalling point and at a lower angle of attack, the different turbulent models exhibited nearly the same value. However, the different turbulent models produced slightly different values for the higher angles of attack, which can be observed from the velocity and pressure contours. For instance, the Realizable k-? and Standard k-? models produce nearly identical lift coefficients up to at Re = 7?105, at Re = 3?106, and at Re = 6?106. Moreover, for all the conditions, the k-? model produces a higher lift value in comparison to the SST k-? model. Furthermore, it is also observed for these three models that lift increases linearly with the angles of attack up to certain values and then fall precipitously with the increasing angle of attack due to flow separation. Again, in the SST k-? model, separation occurs at a small angle of attack as compared to the other two models. This is because the SST k-? model more accurately resolves the viscous layer and flow separation for high-pressure gradients than the other two models. The drag coefficient is increased with the angle of attack and almost the same up to an angle of attack for the Realizable k- ? Model and SST k- ? Model turbulent models. In the case of the Standard k-? Model, the drag coefficient value is different from the other two models at a low Reynolds number but as the Reynolds number increases the difference decreases and at Re = 6?106, the three models produce almost the same drag up to the angle of attack. However, the reason behind all of the similarities and deviations can be explained by the pressure and velocity contour. From the contour, the stagnation point and the pressure difference can be obtained and this pressure difference is the key reason behind the generation of lift. Finally, from the velocity contour, it is clear that the flow separation occurs at the trailing edge for the higher angle of attack, and due to this drag coefficient increases precipitously.
Abstract
Presently stabilizing the vehicles at high speed with fuel optimization has become a field of concern. These two crucial factors are due to two significant forces drag and lift respectively. CFD is becoming a useful technique in current fluid dynamics research, because to the rapid advancement of digital computers. It brings together fluid mechanics, mathematics, and computer science. This work targets to simulate the drag and lift force on simple SEDAN car modeled in SOLIDWORKS tool using ANSYS Fluent platform. This work focused on variation of dominant forces using an add-on device rear spoiler which was designed using NACA 4412 cross section at different angle of attacks. Then the work focused on evaluating optimal angle of attack at which the spoiler is most economic. The work then focused on variation in flow properties and co-efficient with various Reynolds number. Standard k-epsilon model with standard wall functions and second order upwind equations to investigate aerodynamic properties. To acquire the flow structure surrounding a passenger automobile with rear spoiler
Power output and efficiency enhancement of a Polycrystalline-silicon PV module using simple cooling methods
Abstract
To balance out energy derived from fossil fuels, solar energy applications continue to captivate the attention of the research community on a global scale. Employing photovoltaic (PV) modules to gather solar energy is one well-liked strategy. Solar panel power efficiencies deteriorate when temperatures rise during external installations. Therefore, there is a considerable amount of research being done on how to maintain temperatures as low as feasible. For a 50W polycrystalline silicon (Poly-Si) PV module, various cooling strategies have been investigated in this study effort. An experimental setup has been developed to conduct outdoor experiments on mostly sunny days. A data acquisition device was developed employing an ESP 32 microprocessor and various sensors for measuring various factors to assess power output and temperatures (current, voltage, and temperature). In this research, we explored two straightforward cooling techniques: forced air cooling with and without a designed finned heat sink, and natural air cooling. The maximum power output of the Poly-Si panel for natural air cooling is 40W, while the maximum peak power for forced air cooling is 42W. The efficiency of the solar panel for both natural and forced air cooling was calculated to be about 16%. The efficiency of the panel is also quite high in the range of 14-15.9% during the natural air cooling with the heat sink. It is worth noting that the highest efficiency is observed for the longitudinal forced air-cooling method (17.8%) followed by the transverse forced air cooling method with a marginally lower value of 17% employing the finned heat sink.
Preparation of Biocomposite Sheet Incorporation of Buffing Dust and Sugarcane Fiber: It?s Application for Footwear as a Reinforcing Material
Abstract
This study aims to prepare flexible composite sheets from buffing dust waste and post-extracted sugarcane fiber waste through a simple solution casting technique. Natural rubber latex (NRL) was used as a binder material in different mixing ratios. To verify the chemical bonding between buffing dust and sugarcane fiber, FTIR was performed. Thermal stability and morphology of as-prepared composites was confirmed by TGA studies and FESEM analysis. The physical and mechanical properties such as tensile strength, elongation, hardness, water absorption and density of prepared composites with optimum NRL content were augmented by 19, 21, 10, 15 and 21%, respectively, to compare with pure buffing dust sheets. As a consequence, these simple, low-cost, and flexible composite sheets might be a potential material for packaging, interior design, as well as reinforcing element for footwear.
Effect of the burnable absorber on the efficiency of nuclear fuel cycle in VVER-1200 reactor
Abstract
The aim of the present work is to study the significant effect of the burnable absorbers (UO2+Gd2O3) on reactivity, neutron multiplication factor (Keff), burnup, neutron flux distribution, power peaking factor and safety parameters of VVER-1200 reactor. The improvement of fuel economics lead to increase fuel enrichment and also the need to improve the neutron flux distribution and reactivity control. These improvements in neutron flux distribution required the integration of the burnable absorbers in the fuel matrix. . Monte Carlo Serpent code was used to design a three dimensional model for VVER-1200 fuel assembly. The VVER-1200 assembly is loaded in different operation process with 8.0% Gd2O3 as integral burnable absorbers (IBAs). Macro cross-sections collected from Monte Carlo Serpent code were put in COMSOL Multiphysics to get the flux distribution inside the reactor core. The calculations were performed in the normal operation state for the first fuel cycle. The comparison of neutron multiplication factor and neutron flux distribution between the fuel assemblies with gadolinium oxide (Gd2O3) and without gadolinium oxide (Gd2O3) is discussed in this paper. Power peaking factor (PPE) for reactor core safety and boric acid concentration is observed for fuel assembly with burnable absorber and without burnable absorber. The presence of gadolinium oxide plays a significant role in the safety of reactor, where it makes the neutron flux much flattened, and hence minimizes the power peaking specially at the center of the core. So, seeking their influences on the reactor core behaviour is a crucial issue in both reactor core design and operation. Keywords: Burnable Absorber (BA), Multiplication Factor (Keff), Neutron flux, VVER-1200, Power Peaking Factor (PPE)
Comparative studies on drying characteristics, proximate composition and microbial characteristics of marine Silver belly fish.
Abstract
The aim of this work was to study compare with the effect of hot air-microwave heating and sun drying on the drying characteristics, proximate composition analysis and microbial characteristics of fresh Silver belly(LeiognathusBindus)sea fish. Experimental drying curves were obtained at microwave power 200 watt after hot air drying at temperature 50 degree C with constant air velocity 1 m/s. In sun drying process four major parameters Solar Radiation, Relative Humidity, Temperature, and Air velocity were investigated. Comparative proximate composition Such as moisture, crude protein,crude fiber, crude fat, ash, calcium, and phosphorus, of these sample were 28%, 51.28%, 0.68%, 13.57%, 8.88%,2.3%,1.27% respectively for hot air-microwave heating and 37.26%,46.38%,1%,9.11%,8.87%,2.6%,1.41% respectively for sun drying. The amount of bacterial loads was found 5.6?108 CFU/gm for sun drying and 8.3?107CFU/gm hot air-microwave drying. However, the data indicate that lower hot air temperature and microwave power are effective in maintaining the quality of marine fish.
Abstract
Ceramics are one of the most promising materials nowadays in the field of materials science and engineering. Ceramics have proven to be an invaluable material in industrial and high-temperature applications such as refractory bricks, coatings over turbine blades, furnace walls, etc. Because ceramics are naturally brittle, their ability to withstand compression is critical in practical applications. Therefore, their mechanical properties, especially the evaluation of compressive strength, should be carried out using a high-precision universal testing machine. However, a high-precision universal testing machine is not widely available, particularly in the developing and under-developed countries of the world. Therefore, in this current study, we have designed and built a compression device using only locally sourced materials and tools that make it affordable for almost all income groups in the world. A simple gear train was used for driving the machine, which reduced the cost and helped get the ASTM recommended feed rate for compression tests. Along with complexity and cost, it is very difficult to obtain the optimum feed rate for compression testing in the system with hydraulic and pneumatic drive. The building blocks for the compression device are the Arduino, S-type load cell, TCRT sensors, simple gear train, and DC motor. Real-time data was collected through MATLAB interfacing with Arduino. Cast iron is the primary material for the fabrication of the parts of the compression device. As per requirement, gear has been procured from the local market of Rajshahi, Bangladesh. The geometry of the compression device has been developed using SOLIDWORKS, and stresses developed in different mating parts of the compression device have been observed using ANSYS. With MATLAB interfacing, the developed compression device can plot a real-time load vs. deflection graph as well as an excel file containing the values of load and deflection. The compressive strengths of the plastic wood and lanthanum manganite samples were found to be 6.78 MPa and 39.91 MPa, respectively, whereas the value of the corresponding compressive strength from the Universal Testing Machine was 11.34 MPa and 58.45 MPa. We have compared the obtained results with the results of an available Universal Testing Machine (at low deformation resolution) at the same operating condition. Some limitations of the newly developed compression device include the fact that it can only test samples with a length of 10 to 16 mm and that rupture of the sample cannot be detected automatically. A precise distance-measuring sensor could be employed in the future for further development. The addition of a rupture detection system gives the compression device that was designed a higher level of accuracy and reliability. The main advantages are its portability and inexpensive manufacturing costs (USD 530), which can be reduced by at least 20 to 30% by optimizing the size of the parts used in the design.
Numerical Modelling of Non-Newtonian Blood Flow Through Multiple Stenosed Artery
Abstract
In this numerical simulation, the main aim is to identify the flow characteristics of blood flow through multiple stenosed arteries. Various numerical simulations have been performed in the past, with laminar flow and the artery was assumed to have a rigid wall. For assumption, blood is considered a non-Newtonian fluid. This means that a viscous model, namely the Carreau model, was used for the variable viscosity of blood. In multiple stenosis assumptions, the stenosis area is considered as 86% constriction & 75% constriction in the artery vessel. However, stenosis can disrupt the blood flow, resulting in a transition from laminar to turbulent flow when the constriction is sufficiently high. The results of turbulent flow will be analyzed by using the k-? turbulence model in this case. To achieve the numerical solution, a well-known numerical solver named ANSYS FLUENT 18.1 is used. Fluid flow is considered to be steady & axisymmetric. The flow velocity and pressure are changed as a result of the constricted areas of the stenosed arteries. Flow velocity, pressure distribution and wall shear stress of fluid flow are compared to an experimental result after solving the numerical problem. The effects of turbulence intensity & turbulence kinetic energy on multiple stenosed arteries are also discussed. By increasing, the spacing distance blood flow characteristics were also changed. The primarily developed laminar flow behaves more unstable in the stenosed region. Shear stress increases & decreases more quickly in the stenosed regions, so there happened a transitional point in the blood flow as expected at the stenosis region. Thus, resulting in the transition from laminar to turbulent velocity range while flowing from the inlet to the outlet of the modelled section of the artery. A severe level of pressure drop is found at 86% stenosis region compared to 75% stenosis region as was expected. In case of multiple stenosis regions, pressure is dropped in multiple regions which can cause the instability of blood pressure & hamper the human natural blood flow rate and in turn reduce oxygen supply and such blood carried constituents. So multiple stenoses have higher impacts than single stenosis. Flow characteristics for single stenosis differ from multiple stenoses. Multiple stenoses have a higher impact on heart problems than single stenosis. Spacing distances between the multiple stenosis regions have also a great impact. Lower spacing distance has a higher level of discomfort scenario. In the pre-stenotic region fluid flow remains laminar. On the other hand, in the stenotic region flow characteristics remain transitional & in the post stenotic region, the fluid flow behaves as laminar flow again.
Design and Simulation of Wireless Power Transmission System for E-Bike.
Abstract
The use of wireless power transfer (WPT) technologies has become very popular in recent times all around the world. Contactless inductive power transfer (IPT) allows electrical energy to be transferred to fixed or moving consumers without the use of contacts, cables, or slip rings. WPT applications are fast developing not just in the small power devices such as wireless charging for mobile phones and electric toothbrushes, but also in the field of electric vehicles and other niche fields as it is proving a more convenient and flexible system for consumers. In this research, A stationary wireless power transmission system for electric vehicle charging applications is studied, analyzed, and developed. The prime objectives of this research are to analyze the magnetic structure and electrical circuits of the WPT system for electric vehicle applications, to design and optimize a WPT coil, to design and simulate the power electronics circuit, and to develop a virtual simulation WPT charging system for E-bike. The methodology for developing the system is divided into two main sections: one is to develop the magnetic structure and the other one is to design and simulate the electronic circuit. The magnetic structure is developed and simulated in the ?Ansys Electronics Desktop 2021 R1? and ?Matlab R2020a? platform is used for electronic circuits. After analyzing the WPT system, a simulation model of a spiral shape magnetic coupler with a ferrite core is proposed to transfer 431W power over a 15cm air gap for charging a DC160-12 battery which is commonly used in the electric autos in Bangladesh. A series-series resonant topology is adopted as the wireless power transfer DC-DC stage due to the advantages of circuit simplicity, easy analysis, and control. The proposed model can supply 20.84A constant DC current which can fully charge the battery within 7.6 hours and operates at a 20 kHz resonant frequency with 72 % power transfer efficiency over a 15cm air gap, whereas the conventional wired charging system takes 12 hours to fully recharge the battery. The model also shows good resilience in horizontal miss-alignments. For 20 mm, 60 mm, and 100 mm horizontal miss-alignments, the overall efficiencies of the system are 69.8%, 62.6%, and 53.5% respectively. In the future, the system can be further modified for a dynamic wireless power transmission system. WPT applications are rapidly expanding, not only in the sector of tiny power devices like wireless charging for mobile phones and electric toothbrushes but also in the field of electric vehicles and other specialist fields, as they provide consumers with a more convenient and flexible solution. So, this research can play a vital role in the future implementation of the wireless power transmission system in an electric vehicle charging application.
Line Balancing Techniques to Improve Productivity Using Work Sharing Method in Footwear Industry
Abstract
The expanding economy of Bangladesh encourages the expansion of the leather industry. This environment leads to severe competition in the leather products industry, notably in the footwear industry, allowing businesses to develop high-quality items to meet customer demands. To reach the demand, companies must push themselves toward high Productivity. Due to different existing and hidden problems, sometimes, they face challenges in meeting the target capacity. The assembly lines on the production floor should be well-designed and efficiently utilized to solve the problems. Line balancing techniques are very popular in increasing Productivity. Line balancing is an efficient way to enhance assembly line production while lowering cycle time and bottlenecks. Line balancing is the problem of allocating tasks to workstations along an assembly line in the most efficient manner. The primary purpose of this project is to raise the overall Productivity of a single-model assembly line by decreasing bottleneck events, cycle time, and workload distribution at each workstation through line balancing, utilizing line-balancing techniques and the work-sharing approach. Work sharing is an employment arrangement in which two or more persons are engaged on a part-time or reduced-time basis to execute a job that a single full-time employee generally performs. The major purpose of this study is to raise the overall efficiency of a single-model assembly line by reducing non-value-added tasks, cycle time, and workload allocation at each workstation. To increase overall Productivity, the technique chosen involves evaluating the cycle time of the process, identifying non-value-added activities, estimating the total workload on the station, and balancing the workload on each workstation through line balancing.
Indoor water on floor detection using monocular camera based on self-supervised segmentation
Abstract
In this paper, we consider the problem of detecting wet area on the floor inside a room using a monocular camera mounted near the ceiling. We use a set of Gabor filters on a floor image and apply nonlinear transformations on the filtered images in order to create feature images. Based on the feature images we create a feature vector for each pixel in the input image. Then we use K-mean clustering with K=2 on the normalized feature vectors and process the resulting clusters to create wet floor segmentations. Our experimental results show that more than 50 percent of wet area of the entire floor can be detected given that the camera has a limited amount of motion (e.g., pan and tilt motions). This problem appears as a sub-problem in many unmanned monitoring systems. Our method results a fast, low-cost and robust solution for this problem.
Conventional power steering system of vehicle and continuous improvement
Abstract
Steering system helps a driver to change direction of a vehicle. Driver?s physical effort is used in mechanical steering system. Power steering system helps a driver to steer front wheels easily. Conventional power steering uses hydraulic power to reduce steering effort. Techniques are being applied in power steering system for two reasons: to give driver a good steering feel and to reduce vehicle fuel consumption as well as to reduce carbon di-oxide emission. The objective of this paper is to review the applied techniques and to make a comparison between them according to steering feel and energy consumption. Hydraulic actuator model is simulated in MATLAB Simulink to show the power consumption at different flow rates. The developed hydraulic pressure difference between chambers is calculated and multiplying by supply flow rate, power consumption is calculated. Flow rate is the key factor of power steering system which determines the steering feel as well as energy consumption.
Abstract
Carbonisation is a gradual pyrolysis process that converts biomass to a highly carbonaceous, charcoal-like substance. The residue after peeling off the jute fiber is known as jute stick which has a very similar composition to hardwoods. Through a single stage carbonisation process, the jute stick pretreated with metallic salts or using pre-hydrolysis approach generates superior quality charcoal with a high yield. The issue with single stage carbonisation for both pretreated and untreated charcoal is that it cannot be generated at high temperatures (over 400?C) efficiently; the yield percentage declines dramatically beyond 350?C, making large-scale production uneconomical. If the carbonisation procedure can be broken down into several stages with varying heating rates and durations based on the decomposition temperature of functional groups present on the jute stick (primarily hemicellulose, ?-cellulose, and lignin), the yield percentage may be preserved to a greater extent. The overall goal of this study was to produce high-quality charcoal at high temperatures using a three-stage carbonisation process and compare the results to single-stage carbonisation for both pre-treated and untreated jute sticks. The experiment was conducted in three stages with distinctive heating rates and temperature zone for all pre-treated samples. According to the results obtained by proximate analysis, salt impregnated with pre-hydrolysed jute stick charcoal produced the best results, with a yield of roughly 51% and 93% fixed carbon, followed by salt impregnated charcoal with a yield of 39% and 95% fixed carbon. These are both substantially greater than generated charcoal from a single step carbonisation process. Overall, charcoal made in three stages with any of the three forms of pretreatment is far more efficient than charcoal made from raw jute sticks, i.e. without any pretreatment.
Comparative Study on Turbulence Modeling of Blood Flow in Flexible Walled Stenosed Artery
Abstract
Cardiac arrest and stroke are considered as major cause of mortality and disability in the modern world. Prediction of the effect of blockage in the blood flow inside the artery could help us to reduce the death rate due to those diseases. Using biomechanics, a new section of modern engineering, the result of blockage in the artery can be predicted. Several turbulence models have been introduced to predict the fluid flow in various field. The main purpose of this numerical simulation is to find out the better turbulence model to investigate the flow characteristics of blood through a stenosed artery. To find out this, various fluid characteristics like the velocity profile, pressure distribution, streamline, wall shear stress, turbulence intensity, turbulence kinetic energy and energy dissipation rate have been observed. Various numerical simulations have been done before using laminar flow and assuming the artery as rigid wall. But according to the literature, stenosis can cause disrupted flow, prompting the shift from laminar to turbulence. In this study, the result of turbulence flow will be analyzed using four turbulence model (Realizable k-?, RNG k-?, Standard k-?, BSL k-? and SST k-?). Also, in this study, the artery wall was considered as flexible. Properties of artery wall will be taken considering the artery as a linear elastic material. Blood was considered as a Newtonian fluid as the effect of non-Newtonian blood flow is not so different from Newtonian blood flow that is the effect of viscosity in this case. All the properties of blood and artery wall were taken from previous experimental data. The geometry of blood and artery wall was designed in Solidworks. The constriction of artery wall was taken as 50% stenosis. The whole numerical operation was run in a numerical solver named Ansys which run based on finite volume method. System coupling mechanism which is a built-in system of ANSYS was used to build up the two-way fluid structure interaction. The solid part of the geometry (Artery Wall) was meshed in Ansys Static Structure along with the boundary condition. The inner and outer wall surface is taken as fixed. The inner surface of artery wall was selected as fluid solid interface. The fluid portion (Blood) was meshed and the boundary condition is given in the Ansys Fluent section. The blood flow in the inlet was taken as steady for numerical simplification. The blood velocity varies from 700-4500 Re in the artery from place to place. In this simulation the blood velocity was taken for 1000 Re. The dynamic mesh was applied in the fluid wall with coupling enabled. The two setting of solid and fluid is connected to the system coupling. Here due to the flow of blood through stenosed artery the velocity and pressure are changed. Due to this change, a pressure is applied on the artery wall and there will be a deformation. Due to the deformation, there is a changed in velocity and pressure in fluid flow. The whole system affects the turbulence kinetic energy and energy dissipation of fluid flow. Solving the numerical problem, the velocity profile, pressure distribution, streamline, wall shear stress of fluid in wall, turbulence intensity, turbulence kinetic energy and energy dissipation rate of flow were found out and compared with one another. Those comparison shows different results for different turbulence models. It was seen that the k-? model series can predict the flow disturbance in the post stenosis region better in large scale than the k-? model. It gives a conclusion that for this kind of internal flow k-? model is not suitable. Between the different k-? model series, the SST k-? model gives an overall better result than the other two k-? models. In the SST k-? model the eddy creation is high in the post stenosis region. It also gives a little better wall shear and pressure distribution than the other two models. But time consumption is high for the SST k-? model. From the overall analysis, the results get to the point that the SST k-? model is the best turbulence model for this kind of internal flow through flexible walled stenosed artery. Key Words Turbulence models, Steady flow, Flexible wall artery, CFD, Stenosis
The influence of acrylic binder on the quality of pigment printed knitted fabrics
Abstract
Acrylic size is a copolymer of acrylate and a sizing agent for spun yarns that is easy to remove. The mixture has a high adhesive strength, is homogeneous, and is quite stable. Suitable for spun yarn used in low-count textiles, including cotton, CVC, rayon, and denim. Additionally, to being elastic, its coating is also antistatic. The primary purpose of the research work was to analyze the Viscosity of pigment paste, pigment penetration behavior, a relative color strength of Pigment printed fabric, stiffness, and different fastness properties of pigment printed fabrics for different concentrations of acrylic binder (100gm/L,120 gm/L,140 gm/L, and 160 gm/L) at two percentages (4%, Light shade and 5%, Dark shade). The viscometer determined the Viscosity of each pigment paste. Printing was done at lab scale on single jersey cotton, polyester, and CVC knitted fabrics by hand screen frame. The reflectance of Pigment printed fabrics before and after wash was examined in a reflectance spectrophotometer for this work. The K/S values were calculated to determine pigment penetration and the relative color strength% of these samples. The SEM image of printed fabric was distinguishable about increasing pigment penetration% into the fabric due to binder concentrations. On the other hand, the fixing agent did not show such a noticeable effect on pigment penetration. It has been found that wet and dry rubbing fastness increased up to 4.1 and 4.6, respectively, with the increase in binder concentrations. The stiffness graphs also showed a higher trend with increased binder concentration. Experimental data showed that a higher amount of acrylic-based binder could increase the rubbing fastness, pigment penetration, and stiffness but wash and light fastness were almost constant 4 and 5 ratings on the grey and blue scale, respectively. This study focuses on the optimal usage of acrylic binder, which the pigment printing industries have not previously prioritized. This will help improve the overall pigment printing quality and reduce chemical consumption.
Abstract
Physical activity is defined as any bodily movement that necessitates the expenditure of energy and is produced by skeletal muscles. Physical activities can be classified into two categories based on their overall impact on human body. One is aerobic exercise, which is described as any physical activity that involves the use of large muscle groups and causes the body to consume more oxygen than it would at rest [1]. Treadmill running is the most common aerobic exercise nowadays. A treadmill is a machine that allows one to walk, run, or climb while remaining stationary [2]. Bicycling is also an aerobic exercise. People can travel from one place to another using bicycle. It helps them to remain in proper fitness [3]. Having these two devices for two different purposes are costly and requires a plenty of space [4]. So, converting a regular bicycle into a treadmill bicycle fulfills both traveling and exercising purpose. People who are busy with their day-to-day work and don?t have time for exercising, can realize the necessity of treadmill bicycle. Treadmill bicycle ensures a smooth short distance travel with the benefit of burning calories at the same time which a conventional bicycle and a treadmill can?t do so individually. Again, another intention should be to design and construct an eco-friendly vehicle. Treadmill bicycle has a runway attached to a bicycle by replacing the pedal mechanism. It can be used for exercising purpose as well as for transportation purpose. The frame of this bicycle has been fully changed with 90cm ? 60cm rectangular hollow mild steel bar and 14 rollers have been installed between front wheel and two rear wheels. The wheels that have used were conventional van wheels and the rear wheels provide more stability to the vehicle. A mild steel fork was used for connecting the front wheel. A conventional rubber belt was attached over the rollers. When the user walks on the treadmill, the belt moves to the back direction and rotated the treadmill rollers. The power of DC motor which drove the treadmill bicycle has been calculated. The vehicle needs 0.26 hp but this specific rated DC motor was not available in the market. So, a 1 hp DC motor has been used which was the nearest to the calculated one. The initial power is provided by 4 rechargeable lead acid batteries to the DC motor. The DC motor rotated the rearrest roller which was coupled with driven gear of 34 teeth. The driven gear transmitted the power to the driving gear of 38 teeth which supplied the power to the shaft. Two gears were designed to reduce the human effort. The gear ratio was 17:19. As a result, the torque would be higher and the velocity would be lower. Two sprocket and a conventional bicycle chain were used to rotate the rear wheels. A proposed CAD model was prepared in SOLIDWORKS 2020. The performance test of the treadmill bicycle was conducted on various road surfaces such as Asphalt Road, Concrete Road and Brick Road. The average speed was generally higher in asphalt road and it was 11.34 km/h. The lower average speed was in brick road and it was 8.48 km/h. A road mapping software was used to collect the average speed on those particular roads and compared the results with the experimental data. The maximum deviation of average speed was observed is brick road and it was 8.61% and the minimum deviation was 2.22% which was on asphalt road. The design is relatively simple and user friendly. This treadmill bicycle is less expensive than motor bikes, and it is simple to use. Instead of having two different individual devices for transportation and exercise purposes, Treadmill bicycle fulfills both these purposes at minimum cost. It can be operated in most of the areas and any kind of road surfaces It saves a lot of space whereas a bicycle and a treadmill occupy much larger space. Key Words Physical Activity, Aerobic Exercise, Treadmill, Pedal Mechanism, Lead Acid Battery REFERENCES [1] Mantyselka P, Kumpusalo E, Ahonen R, et al. Pain as a reason to visit the doctor: a study in Finnish primary health care. Pain. 89:175?80, 2001. [2] Moskovitz MA. Advances in understanding chronic pain: mechanisms of pain modulation and relationship to treatment. Neurology. 59: S1, 2002. [3] C.R. Ajan, K. Ajay Sugadan, Kashaya Balachandran, Walking E-Bike, International Journal of Innovative Research in Advanced Engineering, 10 (04), pp.68-76, 2007. [4] Inclusive City Maker, "Physical Exercise conditions in the World of 2019: facts and figures," [Online]. Available: https://www.inclusivecitymaker.com/physical-exercise-conditions-in-the-world-of-2019-facts-and-figures/. [Accessed 21 February 2021]
DESIGN AND FABRICATION OF HYBRID COOKING STOVE TO USE RENEWABLE ENERGY IN NON-URBANIZED AREAS
Abstract
Traditional stoves are mostly used for cooking in non-urbanized areas in Bangladesh. Biomass such as wood, leave, cow dung, crop residue, coconut husk, etc. are used for this purpose. Cooking with these biomasses is one of the most significant contributions to global climate change. Besides, unsustainable harvesting of wood for cooking adds to deforestation, which reduces carbon uptake by forests. Traditional stoves also emit huge smoke, creating indoor air pollution and various health problems. These also impact household economy, women?s time and activities, gender roles, safety, and hygiene. To prevent these harmful effects a greener and healthier form of cook stove is required to be used. Emissions from cooking can be reduced by increasing fuel efficiency and introducing alternative fuels from renewable sources of energy. Numerous investigations have been carried out on biomass stoves to enhance performance and minimize the adverse impacts on human health and the global climate. In this study, a Hybrid Stove (FPM-HS) was designed, fabricated, and tested to evaluate its performance. The stove was made of concrete and operates in a dual fuel mode. It emits much less indoor air pollutants compared to a traditional cooking stove. So, it is a perfect alternative to the traditional cooking stove. The Hybrid Stove (FPM-HS) is composed of two sections. These are- Solar Electric Section and Biogas Section. When there is availability of sunlight, the solar panel generates electricity which is passed to the electric burner of the hybrid stove through a wire. As a result, the electric burner gets heated and can perform a cooking operation. In the absence of sunlight, the tray is opened and the gas burner appears. The gas burner is connected to a biogas tank via a gas line pipe. When the nozzle is turned on, the gas from the gas line pipe enters the burner. When the knob is turned on, the intake valve opens and gas flows through a venturi tube which is a wide hose that has a narrow portion in the middle. Gas enters through one of the broad ends, and as it passes through the narrowed section, its pressure increases. There's a small air hole in the section where the hose widens again, and as the gas travels through that section, pressure releases, drawing oxygen into the air hole. Oxygen mixes with the gas and then the mixture of oxygen-gas is flushed into the burner and thus the flame appears. The thermal efficiency of the biogas section of the manufactured Hybrid Cooking Stove was 30.87%, the burning rate 12.16g/min, and the specific fuel consumption 0.06g/g of water. The efficiency of the solar electric section of the Hybrid Stove was 72.07%. The calculated electric energy consumption was found 5kWh/day for 5hrs cooking. It was observed that it takes less time to cook rice in the biogas section of the hybrid stove than in a household gas stove. The study suggested that this technology might be suitable for cooking in non-urbanized areas as well as reduce environmental pollution and meet up the energy crisis.
Abstract
Industries play a vital role in a country's economy and the livelihood of common people. But a matter of concern is that most industries use toxic materials and hazardous chemicals and these dangerous materials are directly discharged into the river water along with the wastewater from the industries. The Bhairab is one of the most important rivers in Khulna that divides the city into two parts. People are highly dependent on this river for fishing and daily uses like cooking, farming, cleaning, and sometimes even drinking. But some industries are situated on the banks of this river, which might put this river at great risk by disposing of their wastes. In this regard, monitoring the quality of the river water and the impact of the industries on it has become of great importance for Khulna city. That's why around 27 km of the river was covered from Rupsha ghat to Fultala and samples were collected from the discharge point of Seven Rings Cement (SRC), a local bone breaking mill (LBBM), household waste mixing point (HHMP), and Superex Leather Ltd. All the samples had been collected around the 100-meter radius of the point sources. The water flow direction was the same for all sample collections. Water quality parameters including TDS, Hardness, ORP, Salinity, DO, pH, Turbidity, BOD, etc. were determined using a digital water quality analyzer and laboratory test. After analyzing and calculating all the data according to the proper method and comparing with ADB, 1994, ECR, 1997, and EQS, 1997, 4 parameters- BOD, Turbidity, ORP, and Hardness were found below the standard. Such quality water is not suitable for drinking and household tasks. Based on the correlation of the parameters, the monitoring of the water quality of the river becomes easier and proper precautions can also be applied beforehand.
An overview of the state-of-the-art inventory management in automobile industries
Abstract
In the post-covid manufacturing scenarios, the world is facing some unprecedented supply chain and inventory problems. Sending essential goods to any part of a country via small vehicles like two-wheeler motorbikes and three-wheeler CNG etc. transports under home-delivery marketing has become inevitable today. So, automobile industries have to meet the increased market demand by producing these and other vehicles to meet orders of people quickly on one hand and to at reduced overall costs on the other. Indeed, production of these vehicles in developing countries is obviously emerging alongside the market is competitive in nature. Automotive industries deal with large number of parts, components and subassemblies per see. Essentially, inventory management has received considerable attention in present times where cost optimization under make-or-buy is a prime objective, given that there are constraints in various terms. The purpose of this article is to figure out the state-of-the-art inventory management incorporating Industry 4.0 concepts in automobile industries with a view to develop some models by reconfiguring the constraints under the given circumstances. Scholarly articles of the relevant researchers and practitioners during 2000-2021 are reviewed to identify the pertinent parameters for optimizing the inventory models for certain crucial parts and subassemblies. They include different journal articles, conference papers, review papers, book chapters etc. especially focused on deterministic type of inventory management system. This systemic review and investigation will locate the gaps in automobile industries? inventory management. This study will lead to develop some inventory models considering multiple parameters and criteria for automotive industries and recommend the appropriate methodology(ies) and technique(s) in different situations for inventory management. Keywords: Inventory management, automotive industry, demand and supply uncertainty, make-or-buy decision, Industry 4.0 .
A Finite Element Method Investigation of Mechanical and Thermal Behavior of Composite Coatings on Steel Bar.
Abstract
Damage to steel structures can be catastrophic in fire incidents due to the ?softening? effect of high temperatures on metals. Various coating materials have been developed to protect steel components from dangerously high fire-related temperatures and increase the overall fire ratings of steel-column high-rise buildings. Intumescent coating is one such spray-painted polymer material that expands at high temperatures and creates a thermal barrier to protect the steel components. In this research, we investigate a new type of intumescent coating material consisting of carbon fiber reinforced polymer composites. As carbon fiber is an excellent thermal conductor, it is expected that the surface heat will be conducted away longitudinally while keeping the inner core of steel material protected. In addition, carbon fiber composites have higher strength-to-weight ratios, meaning these coatings are supposed to increase the component strength and stiffness. The thermomechanical analysis is performed on a Finite Element Analysis (FEA) software. Simulations are carried out for various thicknesses of the composite coating layer. The results show increase in stiffness of the hybrid coated plate with a 7/10/15 mm thickness of the composite layer. Thermal resistance is also increased with the epoxy composite layer. These results suggest that Carbon/Glass fiber-based epoxy composite coatings have the potential to significantly improve the performance and fire ratings of steel structures.
Numerical Analysis of Various Horizontal Axis Wind Turbine Blades and Optimization for Low Wind Velocity
Abstract
Among different renewable energy sources, wind energy is a promising source for harvesting energy, but the main obstacle here is that the wind velocity is not high enough everywhere. Small-scale wind turbine blade output is very small as the power output of wind power is proportional to the square of air velocity. Therefore, research is going on to develop new blades efficient enough to produce electricity at low wind velocity by optimizing blade shape. In this study, two airfoil models NACA 63-415 and NACA 63-412 were analyzed numerically using ANSYS Fluent software. Different aerodynamic properties such as static pressure, dynamic pressure, velocity magnitude, and streamlines were observed. At velocity inlet, the upstream velocity of air is 3m/s for Re=200000. The velocity components are calculated for each angle of attack. For velocity inlet boundary conditions turbulence intensity is considered 1% and for pressure outlet boundary is 5%. In addition, a turbulence viscosity ratio of 10 is used for better approximation. At different angles of attack [0-18 degree] lift coefficient, and drag coefficient, thus, the optimum angle of attack is measured. Blade sections made by the same airfoils are optimized by changing the twist angle. The blade section is twisted from 0 to 16 degrees on a 4 degrees interval. Therefore, the optimum twist angle is calculated 12 degrees where the lift coefficient is maximum compared with the drag coefficient. Keywords: Wind Turbine, NACA 63-415, NACA 63-412, Turbulence, Optimization
Construction and Property Test of a Sugarcane and Molted plastic Sheet Composite
Abstract
The melted plastic and crushed sugarcane bagasse hybrid composite was fabricated in this work. Seven types of samples were produced by varying different proportion of plastic and sugarcane. The composite samples were A1(100% plastic, 0% sugarcane), A2(95% plastic, 5% sugarcane), A3(90% plastic, 10% sugarcane), A4(85% plastic, 15% sugarcane), A5(80% plastic, 20% sugarcane), A6(75% plastic, 25% sugarcane), A7(70% plastic, 30% sugarcane). Then different mechanical properties such as flexural strength test, impact strength test, compressive stress test and thermal conductivity test were done. In flexural Test, A1 composite material shows best flexural strength. The A1 combination of composite also shows best Impact Strength. In compressive Strength test, A7 combination of composite gives the best tensile strength . The best thermal conductivity was given by A1 combination of composite. The least thermal conductivity was given by A7 combination of composite, which means it has the best insulating property. Results are calculated and plotted on Microsoft Excel to compare the data. The A1 combination of composite material gives the best flexural strength. It also gives the best Impact strength. The best compressive property was given by A7 combination of composite. Now it can be concluded that mechanical and physical property of melted plastic and crushed sugarcane bagasse hybrid composite material varies with the change of weight proportion. The composite materials can be used in replacement of plastic, insulating material and window grill.
A Study of Lead (Pb) Pollution Near Lead-Acid Battery Recycling Industries in Khulna
Abstract
Lead (Pb) toxicity is a great threat to humankind and the environment. As Pb-related activities such as Pb-acid battery recycling have grown in popularity, Pb toxicity has been swiftly disseminated across Bangladesh. The primary objective of this research is to examine Pb contamination in the soil of the Pb smelting facilities in the Khulna region. A variety of soil samples were collected (near Pb acid battery recycling industries) and analyzed to determine their Pb content. Dry ashing, extraction, digestion, and atomic absorption spectroscopy (AAS) were used to analyze the soil samples. Pb was detected in varying concentrations at different distances from the Pb acid battery recycling industry's location. The soil samples were found to contain excessive amounts of Pb compared to the background concentration. Pb concentrations were also found to vary according to distance from the Pb melting furnace. It recorded the highest concentration, 292.13 ppm, which is approximately 15 times higher than the background level. This high level of pollution could adversely affect human health, animals, plants, crops, etc. As a result of this study, environmental restorationists and local policymakers can learn more about Pb pollution in Khulna.
Abstract
The cooling and heating of households, factories, and offices consume a substantial amount of our traditional energy sources, such as electricity and fossil fuels, each year. Using renewable energy sources, such as solar, wind, biomass, and ground energy, which produce no emissions or very little, can reduce the enormous volumes of greenhouse gas emissions caused by this, including carbon dioxide, sulfur dioxide, nitrous oxide, and others. Due to its enormous local supply and lack of transportation costs, geothermal energy is rapidly growing as a feasible alternative for generating the energy required for air conditioning. In the winter, the ground is warmer than the surrounding air, while in the summer, it is colder. A Ground-Coupled Heat Exchanger (GCHE) converts the earth?s energy into convenient energy to heat and cool buildings. In the winter it uses the earth as a heat source, while in the summer it uses it as a heat sink. Because they consume 25% to 50% less electricity than conventional heating and cooling systems, heat exchangers are the most energy-efficient heating and cooling technology. Vertical Ground Heat Exchangers (VGHE) and Horizontal Ground Heat Exchangers (HGHE) are the two types of ground heat exchangers (GHEs). Shallow HGHEs generate less energy in comparison to vertical GHEs. According to earlier research on several VGHE kinds, including U-tube, double tube, and multi-tube GHEs, double tube vertical GHEs exhibit better thermal performance than other vertical GHE types. As a result, double tube VGHE has been taken into consideration in our study. The thermal performance of a vertical double-tube ground-coupled heat exchanger in a pile foundation has been investigated numerically in the cooling mode of operation. A ground-coupled heat exchanger (GCHE) exchanges heat between concrete and the underground soil. Ground-coupled heat exchangers (GCHE) are mainly used for HVAC and other heating and cooling purposes. In this work, a two-dimensional axisymmetric model was analyzed numerically by using ANSYS Fluent. The fluid domain was drawn by design. Then the mesh was generated using face meshing, sizing function, and high smoothing. Double precision is applied to the Fluent set-up launcher. Pressure-Based, Absolute Velocity Formulation, transient time step, and axisymmetric solver have been applied. The gravitational acceleration effect was also considered. A velocity inlet type boundary condition is applied in the inlet section and a constant pressure-outlet is used in the outlet section. The operating pressure is set to 1 atm, and the temperature is set to 293.15K. For investigating the performance, 24 hours of continuous operation was considered. Three different borehole length models of 10m, 15m, and 20m are considered where 1 lit/min, 2 lit/min, 3 lit/min, 4 lit/min, 5 lit/min, 6 lit/min, 8 lit/min, 10 lit/min, 15 lit/min, 30 lit/min, 40 lit/min, 60 lit/min, and 100 lit/min flow rates were selected for analysis of the performance. Heat transfer rate, outlet temperature, and pressure drop were listed and were briefly described for every model. The pressure drop was very high from 10 liters per minute to 100 liters per minute and the average heat transfer was very low for a 1 liter per minute flow rate. Heat transfer and pressure drop were balanced for flow rates of 2 liters per minute to 5 liters per minute. The temperature difference between the inlet and outlet was increased when the borehole length was increased. The heat exchange rate and pressure drop are important parameters in the ground-coupled heat exchanger (GCHE) design. The result of this analysis can give constructive information for designing the ground-coupled heat exchanger (GCHE).
Abstract
The growth of SME engineering and manufacturing sector for the past few years is a huge blessing for the economy of Bangladesh by providing for the component marketplace which was saturated by imported and often low grade locally produced products. In conjunction with strengthening the economy by reducing the dependance on imported products and enabling huge job sectors for skilled labor force, the sector also provides the consumer access to advanced grade products in a relatively cheaper cost. To compete against the imported products, these SME manufactured products need to be of the same grade and also exceed the quality of the locally produced products. In this study, microstructural analysis was done of an Al-Si alloy SME manufactured water vessel propeller contrasting with a locally produced one. Microstructure was observed by optical microscope (OM) then further assessed by phase composition, observed with SEM equipped with Energy Dispersive Spectroscopy. The influence of composition and porosity on microstructural properties was discussed. Statistical analysis of microstructural constituents was done and the contrasting difference of the two propeller in microstructural characteristics according to literature were discussed.
Experimentation of Anti-microbial and Mechanical Properties of Cotton Fabric Treated with Aloe Vera Gel, Basil Leaf Extract and Silver Nitrate Nanoparticles
Abstract
The textile finishing and processing sector uses a lot of chemicals and releases dangerous elements into the environment. Natural materials, plant components, and plant extracts that can be used to finish textile materials are given top priority in the sustainable concept. They are motivated by a desire for comfort and environmental protection. Single jersey cotton fabrics were finished using Basil extracts and Aloe Vera gel combined with acrylic binder and also from the in situ synthesis of silver nitrate by pad-dry-cure method. The antimicrobial activities of Aloe Vera gel, Basil extract and Silver nanoparticles (AgNPs) were evaluated against Gram positive bacteria (Staphylococcus aureus) and Gram negative bacteria (Escherichia coli). The appearance of zones of inhibition was used to evaluate the antimicrobial effect. Antimicrobial test showed that Aloe Vera, Basil, and AgNPs inhibited the growth of S. aureus (9.0 mm, 7.0 mm and 9.0 mm) respectively and E. Coli (0.02 mm, 1.0 mm and 4 mm) respectively. To evaluate the mechanical properties of the treated fabrics, tensile strength and elongation at break tests were done. To confirm the physiochemical qualities of the AgNPs treated sample, a Fourier-Transform Infrared Spectroscopy (FTIR) investigation test was performed. This antimicrobial-treated cloth has a wide range of applications in the medical and modern textile field.
Construction and Performance Test of Box-type Solar Cooker with Compound Parabolic Reflector
Abstract
Energy consumption is increasing day by day all over the world. To meet up the increasing energy demand, non-conventional or renewable energy sources have been introduced. Solar energy is one of the major sources of renewable energy. Solar energy could be used in various purposes like heating, drying, cooking, distillation, power generation etc. For cooking, solar energy could be used as a substitute of conventional fuels. Solar cooker is a device for using solar energy in cooking purpose. Box-type cooker is a popular one which is simple in design but less efficient. A new type of design of box cooker was introduced in the present work aiming to improve the performance. A wooden box was constructed with the dimension of 0.7m ? 0.7m ? 0.5m. Five plane glass mirrors were used as outer reflectors to increase the incident solar radiation and a compound parabolic shape aluminum foil as inner reflectors to further concentrate the incident radiation and get higher performance. For insulation, cotton was used between the wooden box and inner parabolic reflectors. Transparent glass was used as cover for creating greenhouse effect inside the box so that heat could be trapped. After developing the solar cooker, experiments were conducted using the solar cooker. Four sets of cooking item (200g rice; 200g rice and 50g lentil; 250g rice and 50g lentil and finally 300g rice and 100g potato) were cooked with the cooker. Maximum temperature recorded for all loading conditions was in between 80 - 90?. Among all data, maximum temperature inside the cooking pot was found 90? whereas minimum temperature was achieved 80? during the experiments. On average 90 minutes time was required for cooking 200g rice, 105 minutes for cooking 200g rice and 50g lentil, 120 minutes for cooking 250g rice and 50g lentil and 130 minutes for cooking 300g rice and 100g potato.
Numerical Analysis of Swirling Jet Impingements for Thermal Management of HCPV using Nanofluids
Abstract
Multijunction solar cells embedded with optical elements, together known as High Concentrator Photovoltaic Module can be a solution to growing demand for renewable energy in both industrial and domestic usages. However, concentration of solar irradiance leads to high temperature leading to performance degradation of the module. For optimum performance, high concentrator photovoltaic modules need to operate within a temperature range of 110?C. Such photovoltaic modules in uncooled state may reach 1400?C under the concentration of 1000 suns. In order to overcome such challenge, an efficient cooling method is required. Thus, main objective of this study is to provide an efficient solution to this problem. In this numerical analysis, RANS based solver using SST k-? turbulence model was adopted to analyze conjugate heat transfer problem where a moderately swirling jet impingements with flow ratio of 0.55 was implemented where two different nanofluids Al2O3-Water nanofluid and CuO-Water nanofluid was used as coolants. This proposed heat sink and flow condition lead to a reduction of cell temperature as low as 72?C for a coolant flow rate of 50 gm/min. This reduction in cell temperature further improved the electrical efficiency of the solar module under investigation.
Morphological Characterization of Bio-Mediated Silver Nanoparticles from Azadirachta Indica (Neem) Leaf Extract
Abstract
A facile, low cost and environment-friendly synthesis process of nanoparticles is very necessary due to the increasing concern for the environment. In this research work, only Azadirachta Indica plant leaf, which is traditionally known as a Neem tree, was chosen as a greener source for the preparation of silver nanoparticles (AgNPs) from silver nitrate precursors. The presence of phytochemicals (alkaloids, flavonoids, proteins, terpenoids, etc.) in Azadirachta Indica leaf extract was mainly responsible to synthesis AgNPs. For the preparation of Azadirachta Indica leaf extract mediated silver nanoparticles (A.I-AgNPs), the synthesis parameters were chosen for pH 8, time 1.5 hrs, temperature 70?C, plant extract: silver nitrate 1:8. The as-prepared A.I-AgNPs were characterized by ultraviolet-visible (UV-vis) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy-dispersive x-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) analysis. After the addition of plant extract into the silver nitrate solution, the color of the reaction mixture was changed from yellow to brown to dip brown which was the visual confirmation of silver nanoparticles formation. The surface plasmon resonance (SPR) characteristic of A.I-AgNPs was analyzed by UV?vis spectrophotometer test. The SPR peak was found at 460nm which confirmed the successful formation of silver nanoparticles. The FE-SEM analysis revealed that most of the nanoparticles are spherical in shape with the size ranging from 45nm to 111nm (average 84nm). EDX analysis showed an intense peak at 3KeV that strongly proved the presence of silver elements. FTIR analysis of the synthesized silver nanoparticles confirmed the presence of different functional groups on the A.I-AgNPs surface which ensured the successful reduction and capping of silver nanoparticles. The successful preparation of A.I-AgNPs suggested that the chosen synthesis parameters can be further used to prepare AgNPs for various applications.
Waste identification and water utilization in the thread dyeing industry: An improvement strategy for long-term development
Abstract
Fierce competition in the textile sector forces one to make a production system more efficient and increase productivity by reducing total throughput time using the Lean manufacturing system. These two objectives can be achieved through Value Stream Mapping (VSM) and process modifications. Water usage is the textile industry's major environmental concern, but little research has been done on how to effectively manage water at the process level by identifying the crucial variables impacting the dyeing water consumption rate. This research targets these objectives in a Textile Dyeing company in Gazipur. Bangladesh's textile thread dyeing industry has a substantial impact on the national economy. Dyeing can be utilized at several phases of the textile-making process. Color is a crucial aspect of the appeal, regardless of how excellent a fabric's construction is. By reducing wastes that are identified at various stages of dyeing thread, the entire process can become more effective and efficient. Utilizing water wisely in the thread dyeing industry may result in a large decrease in water use, ensuring environmental sustainability. This research has been conducted at a reputed sewing thread manufacturing plant to explore the possibility of minimizing water use in the thread dyeing process without hampering the fabric quality and to identify any potential waste generated during the entire process. Non-value-adding activities have been identified for removal, some processes have been streamlined and some processes have been modified. Value stream mapping (VSM), a lean method that uses a flowchart to describe each stage in the production process, was applied to the 34-kilogram batch (the batch that is run the most) to find waste, shorten process cycle times, and implement process improvement. It is possible to gain a broad grasp of what is happening in the production system from this VSM, as opposed to what ought to or might occur. This helps to focus on the few most important reasons for the seven categories of waste it generates and eliminates. The "Radio Frequency Drying" and "Winding" procedures are identified as potential areas for improvement in this VSM, as their inventory and lead time are quite high. According to evaluations of the thread dyeing processing data gathered, there are a variety of variables that affect water consumption, including capacity utilization, product mix, shade depth, First Time Right (FTR), machine wash, and the adoption of new technologies or processes. These changes have a significant impact on productivity improvement.
Electrothermal Analysis of Graphite-Reinforced Metal Matrix Composites for High-Temperature Resistive Heating Applications
Abstract
Resistive heating capability of a graphite-reinforced metal-matrix composite (MMC) is investigated through the corresponding electrothermal responses under a DC field. The steady-state electrothermal behavior of the MMC is analyzed using a direct computational scheme under forced convection air cooling. Tungsten matrix reinforced by graphite fibers is considered as the MMC for its higher melting and operating temperature along with high strength characteristics. The governing partial differential equations are modified to be compatible with solving the multi-domain thermal problem coupled with the electrical problem of composite materials. An efficient iterative scheme is developed to couple the electrical problem with the multi-domain thermal problem. The effect of electrical heating is then post-processed by evaluating the temperature of the working fluid at the exit of the resistive heating unit. The effect of fiber volume fraction and orientation of the graphite fibers in the MMCs is also investigated under similar conditions. It has been observed that the resistive heating capability of the present MMC systems is better than the conventional material, Nichrome. Moreover, the resistive heating ability of the MMC increases significantly at higher volume fractions of graphite in both the fiber orientations, although the rising trends are different.
Experimental Investigation on Mechanical Characteristics of Jute and Bamboo Reinforced Epoxy Hybrid Composite
Abstract
Experimental investigation on mechanical properties of jute and bamboo reinforced epoxy hybrid composite has been conducted in this study. The objectives of this experiment were to fabricate jute and bamboo based composite and to conduct destructive and non-destructive tests to evaluate mechanical properties. Two orientations of jute fiber which are unidirectional and twill type has been combined with unidirectional bamboo mat, and a total of four types of composites has been formed. Chemically treated bamboo strips has been used to fabricate bamboo mats, and jute yarn has been used to fabricate unidirectional mats using special type of manual handloom. From the experimental result, it was found that higher mechanical properties were found where unidirectional jute mats in the middle of jute-bamboo hybrid composites.
Abstract
Increasing demand for the superior material properties have turned our thinking from a single material to composite. Traditionally composite material consists of continuous phase of the matrix bearing the discontinuous phase of the reinforcement that carry the main load. Commonly used matrix materials for Metal Matrix Composites (MMC) are aluminum, magnesium, titanium, copper etc. Among various MMCs, aluminum metal matrix composites (AMMC) have distinct properties like better strength, lightweight corrosion resistance. Addition of reinforced metals in the pure aluminum improves the mechanical properties of aluminum. This paper focuses on the casting of aluminum metal matrix composite where Magnesium (Mg) of two different weight fraction is used as reinforced metal. The Al-Mg metal matrix with 1wt% and 2wt% Mg is fabricated using the stir casting method. Initially, aluminum and magnesium are preheated in two separate furnaces before being mixed. Then the preheated aluminum matrix is poured into the furnace whose temperature is elevated to 6700C. When the aluminum is completely melted, preheated magnesium is added with manual mixing. Afterwards, the stirring is performed at a speed of 600 rpm to accomplish the mechanical mixing. Finally, the mixture of matrix and reinforcement material is transferred into the molds. The mechanical tests are performed to check the properties like tensile strength, impact strength, and hardness. With the addition of magnesium, hardness and impact strength are increased gradually while the ultimate tensile strength and ductility shows a different trend. Initially the tensile strength and ductility are reached to the highest value for 1wt% Mg and then it is decreased at the next weight percentage due to the brittleness of the material. Therefore, these properties have the significance to apply this material where the seeking properties are hardness and impact strength.
Abstract
Md. Adnan Bin Aziz1 Md. Asfak Uddin2 1,2Department of Chemical Engineering Khulna University off Engineering and Technology, Khulna The decrease in drinking water quality has become a matter of concern for living organisms over the years. This paper shows the physical and chemical characteristics of five different drinking water supplies for the residents of Teligati region, Khulna. Both treated water supply and natural water supplies were taken into consideration for the research. The purpose of this research is to properly understand the Drinking Water Quality Index that is being compromised for various geographical and artificially created problems. .Using proper experiments conducted in the Environmental Lab of KUET, this study was conducted to determine the specific values of BOD, COD, DO, pH, TH, EC, Chloride concentration, Turbidity, Color, TSS and TDS of five different samples taken for five major Drinking water supplies of Teligati, KUET. All the data collected were compared with different parameters set by WHO and the deviations were calculated. From the experimental data, The drinking water supply from BSMRH Hall, fairly deep tube well (290 feet) situated close to the area and the water Supplied in the outside restaurants met the parameters set by WHO and the other two just fell inside of the parameter. The other two supplies the non treated drinking water supply from BSMRH hall of KUET and Shallow tube well situated in the area was also very close to the allowed range set by WHO. The BSMRH hall drinking water supply was treated for drinking and the other four supplies were natural. This study definitely confirms the fluctuation of the Drinking water quality index but it rarely surpasses the WQI. The treating method needs improvement and more modern techniques need to be applied. The shallow tube wells need to go out. Further bacteriological and spectrophotometric ion detection methods should be conducted in further studies for the detection of heavy metals like arsenic, mercury, lead and also total coliform count. Keywords: Water Quality Index, Shallow Tube well, treated water,coliform Corresponding Author: S.K. Yasir Arafat Siddiki Assistant Professor,Department of Chemical Engineering,KUET Mobile: 01914131268 Email: [email protected]
Evaluation of a Different Model of Affordable Eco Cooler Using Thermoelectric Module and Joule Thomson Effect and It's Social Aspects
Abstract
Researchers have lately shown an interest in developing piezoelectric technology as a particularly noble cooling method definitely due to its obvious benefits over compression refrigeration methods like the absence of a compressor, refrigerator, moving parts, and other components. The Peltier effect or piezoelectric effect is the inverse of the Seebeck effect, in which an electrical current passing through a junction connecting two materials emits or absorbs heat per unit time at the junction to balance the chemical very potential difference between the two materials. However, very few models of these types of air coolers kind of have been tested so far in a subtle way. This research particularly focuses on a unique model of thermoelectric air cooler which also includes the Joule Thomson effect of air. The Joule-Thomson effect, also known as the Joule-Kelvin effect, is the temperature shift that occurs when a gas expands without doing work or transferring heat. The objective of this research is to provide an affordable cooling solution for the lower-income people living in slums and mountainous regions where the supply of enough electricity is a big issue. A cone-shaped physical model made of Polylactic acid has been 3D printed to generate the Joule Thomson effect and six Peltier modules have been set radially to strain the Thermoelectric effect. A forced draft fan is used to supply the required air with very high velocity and pressure. The air suddenly expands at the outlet of the cone as the pressure drops and creates the Joule Thomson effect. Without turning on the Peltier the temperature falls only 0.3-0.4 degrees Celsius really due to the Joule Thomson. The outlet temperature of the air has been found to decrease drastically (4-12 degrees Celsius) with the number of Peltier modules that have been switched on, also with the increase of voltage of the Peltier. But the performance of the eco-cooler decreases after turning on a particularly certain amount of Peltier, which gives a cutoff point showing that it will not be economically feasible to use kind of more Peltier in an actual big way. Also, the velocity and pressure of the inlet air have been varied to find out the most effective and cost-efficient point. This product will not only be cost-efficient but also will be environmentally friendly in a very big way. The contribution of air conditioners to global warming definitely is turning out to mostly be a great threat these days as according to statistics they basically generate around 100 million tons of Carbon Dioxide each year. This model can kind of prove to be a pretty great deal from this aspect for being both environmentally friendly and fairly low in energy consumption. The social acceptance of the kind of cooler mostly has been quite a large issue also. Thus, a survey has been conducted on 50 middle-class to really poor people of Mirpur 11 (Paris Road slums) and Vashantek where the importance of this kind of cooler has particularly become. Around 76% of them found it useful and generally were very kind of interested in it being set in their houses, which is quite significant. Around 18% of them are satisfied with their actual current condition and the rest of the 6% of them didn?t specifically want to comment on this matter. However, a presence of doubt in the mind of basically many people about the lifespan of this product sustains.
An Intelligent Hybrid Manufacturing System for FDM Surface Defects Monitoring with Industry 4.0
Abstract
Additive manufacturing (AM) and machining in a single machine colloquially known as Hybrid manufacturing help to produce customized and complex products without assembling including greater design freedom and reduced material wastage. A CNC-based grinding mechanism is introduced in the same system to overcome those defects and enhance the quality. To increase productivity and improve product surface quality, evolving additive manufacturing demand and finishing subtractive processes must be combined on the same platform. For the additive manufacturing method, Fused Deposition Modeling (FDM) has been employed, and a grinding operation can be performed for surface finishing. A camera module is used to capture surface images for defect detection such as stringing, rashing, and surface cracking after the AM process. Convolutional Neural Network (CNN) is applied to the captured image for the defect detection process. If the CNN analysis reveals any surface defects, a grinding operation will be performed on the surface for better surface quality. The architecture has provided a platform to collect data from the image captured by the camera module for evaluating and identifying surface defects using CNN. CNN model provided 89% accuracy for surface defects detection. As a result, the CNC grinding operation can be done on that particular surface of the product for smoothing the partially roughened surfaces. Therefore, this study demonstrates to improve the surface quality, reduce cycle time, set up time reduction & improve the product's sustainability. The proposed approach of a hybrid manufacturing system also provides a basic framework to increase efficiency, reduce downtime, increase efficiency, improve end part consistencies of the product as a consequence of post-processing & defect detection in the same system, and enable I4.0
Effect of Hydraulic Jump on a Moving Surface by Slot Jet Impingement: A Numerical Approach
Abstract
This numerical investigation focuses on the effect of hydraulic jump on a moving flat surface due to jet impingement. Liquid jet impingement is broadly used in cooling applications because of its high heat transfer capability. Because it spreads radially after the jet impinges on a flat surface, the hydraulic jump affects the total amount of heat that is transferred, making it an essential component of the heat transfer study of jet impingement. The governing equations are solved numerically using the FVM method by ANSYS Fluent: a commercial CFD package. The results covered the effect of hydraulic jump on fluid flow and heat transfer characteristics on a flat surface for two different Reynold?s number of 23,000 and 50,000. The effect of different plate velocities (Up) is also considered for the simulation process to determine the hydraulic jump on the flat surface. The local Nusselt number and skin friction coefficient and pressure coefficient at the heated moving plate is presented. The study suggests that the heat transfer characteristics increased due to the effect of the hydraulic jump for higher plate velocity. The analysis also reveals that the jet exit Reynold?s number and the plate velocity have a significant positive correlation with a substantial rise in the heat transfer phenomena. These key findings are engendered from the influence of hydraulic jump on thinning the boundary layer.
Effect of Length of Composite on CFRP Strengthened Steel Beam-Column Joints Under Cyclic Load
Abstract
Steel structures are known for being highly durable and therefore used in many modern structural applications. However, these steel members are not invulnerable to deterioration. Steel I-beams can be subjected to corrosion, fatigue, a high intensity load, progressive loss in strength with time etc. and cause deterioration. Once a structure becomes deteriorated, it is important to repair or strengthen the deteriorated steel structure. Replacing them all together can be too costly and difficult, and that is why strengthening is preferred. In recent years, strengthening of steel beams using fiber-reinforced polymers such as Carbon Fiber Reinforced Polymer (CFRP) has gained much attention in various research fields. They are sometimes preferred over conventional reinforcement methods such as welding, bolting, riveting etc. These methods may induce high stress concentration around holes and therefore may not be suitable for all applications. Composite reinforcement has gained favor over other conventional reinforcement methods due to their lightweight, high strength to weight ratio, corrosion resistance, high flexural strength, and their quality over all other repairing or strengthening members in steel structures. Several numerical and experimental studies about CFRP reinforcement of steel structures had been carried out for static load in past. In this paper, the numerical analysis of CFRP bonded along with bare steel beam-column joint has been carried out under cyclic loading. The parameter which is considered during this analysis is the effect of the length of CFRP sheet used for reinforcement. The finite element software ?ANSYS 2020 R1? has been used to carry out this numerical analysis. The effect of CFRP is studied using different characteristics which are load-deflection, energy dissipation, time-moment, strain of beam, average stress of CFRP, shear stress of CFRP, normal strain of CFRP and the delamination of CFRP. It was found that CFRP strengthening can improve the load-bearing capacity for structural steel beam-column members and that the strengthening properties improved along with increasing length.
Eco-Friendly Degumming of Silk Fabric and Evaluation of Antimicrobial Properties
Abstract
The degumming of silk eliminates the cementing sericin layer from the surface, improving its color, texture, luster, absorbency, and drape while keeping the fibrous component, fibroin, intact. To transform raw silk into clothing, the process of degumming silk is obligatory; however, this process is usually followed by harmful chemicals. This work aims to perform eco-friendly degumming by optimizing the removal of the sericin content from silk fully or partially, as residual Sericin on silk can be used as an antimicrobial agent. This paper also studied the effect of the eco-friendly degumming process using papain-extracted protease enzyme and citric acid from lime on spun Silk fabric in different ratios. Subsequently, a comparative study is also made with the conventional alkaline/soap degumming process. In order to evaluate the degumming percentages, weight loss values supported by water vapor permeability and water absorbency tests were performed. Though conventional Alkali/soap treatment showed better results on degumming (23% wt. loss) over enzymatic degumming (10.82% wt. loss), there remains a question on the effect on the environment as well as on antimicrobial properties. To increase the antimicrobial properties of the fabric, naturally extracted Aloe Vera was used in various processes, including dip-pad-dry coating and spin coating. Agar well diffusion technique was used to evaluate the antimicrobial activity of the specimens with gram-positive bacteria E.coli and gram-negative bacteria S.aureus. Aloe Vera gel applied by dip-pad-dry method without binder showed maximum resistance to both types of bacteria. The antimicrobial properties of treated fabrics were also compared against raw and degummed silk fabric. The result showed better water absorbency and stronger antimicrobial resistance in Aloe Vera treated degummed silk fabric.
Unsteady Convection and Mass Transport over a Stretching Sheet in a Saturated Porous Medium with Magnetic Field
Abstract
An analysis of a time-dependent magneto-convective heat-mass transport upon a stretching sheet in a saturated permeable medium with the magnetic field are discussed. The governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) by imposing the similarity transformation. The transformed governing ODEs are solved numerically using finite difference method by shooting technique in ODE45 MATLAB software. The numerical results are shown graphically and tabular form performing the impacts of several non-dimensional parameters/numbers entering into the current problem. With an increase in the values of the Darcy number and magnetic force parameter reduction in the fluid velocity. The concentration and the temperature of the fluid decrease for moving values of the Schmidt number and the Prandtl number, respectively. The mass transfer rate increases by about 46%, due to increasing the Schmidt number (0.5-1.0). The heat transfer rate increases by about 22% due to improving the Prandtl number (0.71-1.0). The local skin-friction coefficient decreases by about 24% and 21% due to improving the magnetic force parameter (1.5-3.0) and Darcy number (0.6-1.6), respectively.
Heat Transfer and Fluid Flow Analysis in a Corrugated Plate Heat Exchanger
Abstract
The corrugated plate heat exchangers have some significant benefits over the orthodox heat exchangers due to easy maintenance and assembly-disassembly capability. This type of heat exchanger usually focuses on improving geometry by increasing the surface area in a heat exchanger and the heat transfer rate from plate to fluid. It works in an efficient manner for both single-phase and two-phase flow. In this study, we evaluated the performance in case of heat transfer and fluid flow of a modified geometry of a corrugated plate heat exchanger numerically using ANSYS- Fluent 20R1. A transient, pressure-based model was selected for the analysis. For the turbulence model, k-? SST was chosen. A nanofluid, base fluid of water containing nanoparticles of a metallic oxide (Al2O3) was used to enhance thermal conductivity. A wide range of Reynolds numbers (1000-12000) were taken into account. The effects of nanofluid on Nusselt number and Heat transfer coefficient for the volume fraction of 0.2-2 were studied. The temperature distribution at different volume fractions inside the heat exchanger was also studied. At the hot outlet, temperature increases; at the cold outlet, temperature decreases with the increase in Reynolds number. The heat transfer coefficient was increased with the increase of volume fraction of Al2O3, while the surface Nusselt number decreased with the increase of volume fraction. The lowest heat transfer coefficient was found to be 12605.46 W/m2K for volume fraction 0.2 and the highest heat transfer coefficient was found to be 13017.43 W/m2K for the volume fraction 2.0. On the other hand, for the surface Nusselt number, the maximum value was found to be 122.16 for volume fraction 0.2 and the minimum value was found to be 199.5 for volume fraction 2.0.
NUMERICAL STUDY OF HEAT TRANSFER FROM A HEATED FLAT SURFACE DUE TO TURBULENT COAXIAL CO AND COUNTER-ROTATING SWIRLING IMPINGING JETS
Abstract
The present paper investigates the fluid flow and heat transfer processes due to turbulent coaxial co- and counter-rotating swirling jets, impinging on an isothermally heated flat surface. The ratio of the inner to the outer diameter of the coaxial jet is 0.35 and the Reynolds number based on the outer diameter is 25,000, while the velocity ratio of the coaxial jet (defined as the ratio of the inner and the outer jet mean axial velocities) is kept as unity in the current study. The jet inlet swirl strength is varied as 0, 0.44, and 1.25 with co and counter-rotating swirl directions for the inner and outer jets, and the non-dimensional jet exit to target plate separation distance is varied from 0.5 to 2. The numerical model with highly refined mesh using ANSYS Fluent commercial code is validated against published experimental and numerical data on the same geometrical flow configuration for non-swirling coaxial jets. The SST k-? turbulence model is chosen for the computations as it shows good agreement with the published data compared to that of the other turbulence models. The streamlines, isotherms, swirl velocity, radial velocity, pressure coefficient distribution and the local, peak and average Nusselt number distribution at the heated surface show the impact of swirl motion and separation distance on the flow characteristics and heat transfer process. The effects of the flow parameters on the flow and heat transfer are analyzed, discussed, and presented.
Effect of Suction on Unsteady MHD Free Convection and Mass Transfer Flow past a Continuous Permeable Sheet
Abstract
The effect of transpiration on the time-dependent MHD natural convective heat and mass transfer fluid flow past a continuous porous plate has been investigated numerically. We have changed the partial differential equations into ordinary differential equations by considering the similarity transformation. The changed governing ODEs were then solved numerically using the finite difference method through the shooting technique in ODE45 MATLAB software. The numerical results are shown graphically performing the impacts of several non-dimensional parameters/numbers entering into the current problem. The velocity of the fluid diminishes for improving values of the inclined angle, magnetic force parameter, suction parameter, Schmidt number, and Prandtl number but the inverse situation is found in the velocity profile for enhancing values of the Darcy number. The temperature of the fluid lessens for improving values of the Prandtl number and the suction parameter. With rising values of the suction parameter and Schmidt number the fluid concentration diminishes. With increasing values of the suction parameter from 0.5 to 1.0 and the Prandtl number from 0.71 to 1.0, the heat transfer rate improves by about 36% and 25%, respectively. The local skin friction coefficient enhances by about 32% for augmented values of the Darcy number from 0.5 to 2.0. On the other hand, with enhancing values of the suction from 0.5 to 3.0, the inclined angle from 00 to 600, Prandtl number from 0.71 to 7.0, and Schmidt number from 0.22 to 0.67 the local skin friction coefficient diminishes about 40%, 67%, 33% and 17% respectively. The mass transfer rate enhances about 68% and 90% due to improving values of the suction parameter from 0.5 to 3.0 and Schmidt number from 0.22 to 0.67, respectively.
Comparison of Aerodynamic Performance of NACA 23012 and NACA 4412 Airfoil: A Numerical Approach
Abstract
Two of the most widely used airfoils worldwide are NACA 23012 and NACA 4412. The purpose of this study is to investigate and compare the aerodynamic characteristics of these two airfoils for a constant Reynolds number of 5?10^6. These simulations were conducted in 2D using Spalart-Allmaras as turbulence model by ANSYS Fluent. Numerical results demonstrate that the lift coefficient increases with the angle of attack up to certain values, after that it decreases due to flow separation. The drag coefficient also increases with the angle of attack for both airfoils. However, the rate of increment is much higher after a certain angle of attack due to flow separation. Results also show that the lift coefficient is much higher for NACA 4412 compared to NACA 23012 for each angle of attack. It also observed that the critical angle of attack for NACA 23012 is 18?, whereas flow is separated one degree earlier in NACA 4412. The whole set of simulated results can be considered as a reference to validate computational fluid dynamics analyses of similar studies.
Developing Biodegradable and Cattle Edible Composite film for replacing non-biodegradable food packages (single use plastics)
Abstract
Nowadays, food packaging is manufactured keeping environmental safety in mind. That's why researchers have started making edible and biodegradable plastics and composites. Though human edible plastics are found in some advanced countries, in Bangladesh, edible food packages would be harmful to human digestion because of the polluted surroundings. Keeping that in mind, cattle edible food packages would be more suitable for Bangladesh, especially with a large cattle population. Moreover, in Bangladesh, a significant portion of single use plastic comes from food packages. Considering all these situations, in this experimental paper, cattle edible food package was developed which was biodegradable, antimicrobial, and oxidation resistant. The objectives of making this composite film were to reduce the use of single use plastics and non-biodegradable food packages and test the characteristics of the composite films. It is a composite film made with Gelatin (bio-polymer), food-grade glycerin, and grass extract. The resulting composite film could replace non-biodegradable polythene, multi-layer films (MLF), and especially single use food packaging. Firstly Gelatin, glycerin, grass, and water were mixed at a specific ratio. Then the mixture was heated, and later it was slowly cooled for three days. The biodegradability, melting point, moisture content, and cattle edibility tests were completed for the composite film. The composite film was found to be cattle edible with a biodegradability of 4.12% per day with a moisture content of 18.71%. It had a melting point of 102?C. Compared with typical food packages, it had relatively more moisture content and less melting point. Due to some economic and laboratory limitations, some errors and limitations were found, such as the composite film being weak and short, along with a slow developing process. Keywords: MLF, Active Food Packaging, Cattle Edible Plastic, Oxidation, Antimicrobial
A Robust Electricity Demand Forecasting of Rajshahi Metropolitan City of Bangladesh
Abstract
Analysis of electricity demand serves as a foundation to understand the trend of demand and related variability which helps to plan for the distribution of electricity to a region. Fuzzy linear regression uses fuzzy parameters to represent ambiguous and imprecise relationships between dependent and independent variables which omits the limitations of conventional linear model. In this paper, robust optimization has been used to increase the feasibility while working with uncertainty in input data. A combined Interval-Ellipsoidal Robust Counterpart of the fuzzy linear regression model is used to analyze the data. To formulate the Robust Fuzzy Linear Regression model (RFLR), the quantity of customers and the average yearly temperature have been regarded as independent variables, while the consumption of electricity has been regarded as a dependent variable. The proposed method has been applied to forecast electricity demand of Rajshahi City. The optimal solution of the linear model has been obtained using the Lingo software. The results show the capability of the RFLR to analyze data uncertainty with more accuracy and it is demonstrated that the inaccuracy in forecasting and estimated fuzzy bands grow as the data perturbation increases.
Investigation the effects of mass of active materials of lead-acid battery on active mass utilization coefficient
Abstract
The lead-acid battery has been widely applied in the fields of electric vehicles, IPS, Solar Power Station etc. due to its advantages of high power, long lifespan, availability of electricity, low cost etc. In this study, 80 pieces lead- acid batteries are adopted to explore the effects of variation of mass of active materials of negative and positive plates on active material utilization co-efficient. Batteries are categorized into four samples according to the mass of active materials of the plates and in every samples has 20 pieces similar batteries of similar plates and active materials. The batteries are charged according to the constant current charging process. After that capacity of the batteries are measured using constant current discharging process. Comparing the capacity found from the research, an optimal combination of plates will be found which will give the best active mass utilization co-efficient. Keywords: Lead-acid battery, constant current charge, constant current discharge, active material, active mass utilization coefficient, capacity of battery
Study of analyzing the flammable area from releasing LPG during filling the bottle in the LPG plant
Abstract
The prevalence of LPG leakage is a threat to the safety of adjacent residents, the quality of the air, and occupational safety. It is necessary to analyze the toxicity of the releasing LPG for environmental safety and human health. The study is mainly concerned with the dangers posed by LPG emissions during bottling into cylinders. In this study, the areal location of hazardous atmosphere (ALOHA) models have been used to evaluate the risk of fire and explosion from various LPG compounds assuming variable amount of LPG released into the environment with constant wind velocity. The flammable area of the isobutene was less than the propane and butane. Consequences of hazards such as the release of hazardous substances into the environment are one of the most important tasks in increasing the degree of safety at the design stage or operation of industrial units. It's essential to assess fluid behavior after exposure to the environment, as well as the resulting emissions and potential injuries, as well as the safest radius for fire, explosion, and hazardous emissions. The results were utilized to derive appropriate evaluations of risk assessments, which can be made accessible to the industry in the hopes of reducing the possible effect of such accidents in the future.
Abstract
Energy is a crucial and vital thing needed for every living being everywhere every moment. It can be produced from various sources in different manners. But the necessity of clean, environment friendly, sustainable and renewable energy production is a burning question in recent years as petroleum-based fuels are depleting due to their excessive use. Among all other alternatives, biomass may be one of the primary and better choices as a sustainable renewable energy source. The motive of this research work was to identify a better feedstock for biofuel production. More specifically, the aim was to produce biodiesel from a specific species of algae. The production method involved in this work was trans-esterification which is an efficient method for biodiesel production. The findings of the experiment indicated that a total of 280 gm of dry algae powder chemically extracted 137 ml of algal oil and subsequently that algal oil was trans-esterified to 115 ml of biodiesel and 25 ml of glycerol as by-product. The conversion rate of dry algae to biodiesel was around 42%, while the conversion rate of algal oil to biodiesel was over 84%. Properties such as Cetane number, density, viscosity, boiling point, and calorific value of the derived biodiesel were 61.8, 0.8859 gm/cm3, 3.83 cSt, 305.5?C and 35.71 MJ/kg respectively which are very similar to the properties of petroleum diesel or other biomass-derived diesel.
An Experimental Study of the Front Left Toe-in angle on Fuel Consumption and Traveling Cost for a Light Vehicle
Abstract
The wheel front left toe-in angle is an important factor affecting the rolling resistance and energy consumption of automotive vehicles. The increase in rolling resistance and energy consumption led to an increase in fuel consumption rate and travel cost for the light vehicle. In this study, the fuel performance of a light vehicle (TOYOTA ECHO PLUS-2ZZ-GE-02 model) has been analyzed to find the changes in fuel consumption by changing the front left toe-in angle of the car. The test results suggest that wheel front left toe-in angle was strongly correlated with rolling resistance, energy consumption, fuel consumption and travel cost. It was found that due to misalignment of front left toe-in angle (from 0.00? to 2.53?), the car traveled approximately 4.76 km less for the same amount of fuel, and the fuel consumption increment w.r.t. no misalignment condition was up to 38.22%. The rate of increase in rolling resistance was found to be about 75.29% as the front left toe-in angle increased (from 0.00? to 2.53?). It was found that the traveling cost per kilometer was increased $0.0645 to $0.0891as the front left toe-in angle increased from 0.00? to 2.53?. The Pearson?s correlation coefficient was found to be rxy = 0.99; which proves a very strong positive correlation between fuel consumption and the front left toe-in angle. Finally, it was suggested that proper wheel alignment of the automobile needs to be maintained to improve fuel performance.
Design, Simulation and Experimental Validation of a Minor Flow Channel Based Virtual Impactor to Generate Mono-Disperse Aerosols
Abstract
The controlled release of mono-disperse aerosols can lower pollution and improve the environment and public health in Bangladesh, a developing country in South Asia. Different aerosol generation systems, such as conventional and virtual impactors (VI) mostly jet impactor, rectangular jet virtual impactor, slot-in-line virtual impactor, dichotomous virtual impactor and cascade impactor have been identified so far for the aerosol research based on condensation, penetration, atomization, and diffusion. To ensure uniformity in the dispersed or suspended aerosols, both conventional and virtual impactors can be used. The virtual impactors substitute a fake area of the slowly drifting air for the impaction region. Mono-disperse aerosol can be produced using a variety of techniques and methods, however the virtualized mono-disperse aerosol generating system with impaction plate might be a viable choice with many application domains. In order to address issues like the re-suspension of impacted particles, a virtual impactor has been designed, and the flow of aerosol particles inside the impactor has been simulated. By dividing the flow streams, the impaction surface is in this instance substituted by a minor collecting flow, giving rise to the concept virtual. Particles that are too small to be collected in the minor flow are carried out of the side of the virtual impactor by the "major flow," which is the bigger proportion of the flow. In this study, a virtual impactor with a single air intake, a minor stream channel that is inclined at 450 degrees to the inlet aerosol flow path, and a particle generator are designed, numerically analyzed, and tested for performance. The intended impactor's distribution of velocity profile, distribution of pressure, tracking of particles, and erosion contour have all shown simulation results. Wall losses of the virtual impactor have also been analyzed. The liquid mixture of 80% ethanol and 20% olive oil is used to create the mono-disperse aerosol. The minimum GSD (Geometric Standard Deviation) for this aerosol has been found to be 1.22 at an air flow rate of 56.6 lpm to the virtual impactor, and the NMAD (Number Mean Aerodynamic Diameter) has been determined to be 0.475 ?m. For a minor flow of 13.28%, the monodisperse aerosol has been produced. A comparative study has been done between different types of impactors of aerosol generation systems with the designed and simulated virtual impactor based on design, mono-disperse aerosol generation and performance.
Design, Fabrication and Performance Analysis of a Subsonic Open-Circuit Wind Tunnel
Abstract
A wind tunnel is a facility that is used to investigate and analyze the aerodynamic forces acting on objects. Therefore, the wind tunnel design is critical to its successful operation in order to provide an advantageous environment. In this work, an open-circuit subsonic wind tunnel was designed, fabricated and characteristics parameters were tested. The wind tunnel consists of test section (of 0.457 m ? 0.457 m ? 0.457 m, contraction part of length 0.635 m and contraction ratio of 7), and diffuser having a length of 0.762 m and diffuser ratio of 1.4. From the flow characteristics analysis of the wind tunnel, the maximum air velocity was found at the mid-section of the test chamber and zero at the wall, which confirms suitability of design and construction. Moreover, the performance of a heat exchanger was tested by placing a heat exchanger inside the test chamber where hot water was flowing through copper tubes and air streams flowing across the external surface. The results showed that the water flow rate, air flow rate, and inlet water temperature had an impact on heat transfer.chamber. The maximum air velocity was found at the mid-section of the test chamber and the air velocity at the mid-section is greater than the wall side of the test chamber because of the no-slip condition and relative motions between different layers of air. Furthermore, the performance of a heat exchanger was tested by placing a heat exchanger inside the test chamber where hot water was flowing through copper tubes and air streams flowing across the external surface. The results showed that the water flow rate, air flow rate, and inlet water temperature had an impact on heat transfer.
Abstract
In leather processing, chrome tanning is the most popular due to its high thermal stability and flexibility. In chrome tanning, 8% basic chromium sulfate (BCS) is used based on pelt weight. The pelt absorbs only 60% of chromium and 40% of chromium remains in the spent liquor. In Bangladesh, generally this trivalent chromium, Cr(III) is directly discharged into the environment without any treatment, which affects the corresponding ecological system causing serious health hazards like cancer when converted into hexavalent Cr. The Cr is deposited in ionic form into the crops and fatty tissue of animals and fish. This deposited Cr enters the human body through Cr-contaminated vegetables, fish, and meat consumption. The utilization of this remaining Cr from waste liquor could break the cycle at the same time provide a waste-to-wealth approach. In this work, recovered chrome from spent Cr liquor was used for the tanning process instead of BCS for wet-blue production and compared with conventionally tanned leather. The basicity of the recovered Cr was 33% and the amount of Cr was 3380 mg/L, respectively. The pollution load in the wastewater was characterized after reused by Biochemical Oxygen Demand (BOD) (1156 mg/L), Chemical Oxygen Demand (COD) (2345 mg/L), chloride (42 mg/L), sulfide (35 mg/L), etc. Physical properties were analyzed by examining the tensile strength of a maximum of 289 kg/cm2 in the parallel direction and 364 kg/cm2 in the perpendicular direction and the percentage of elongation of a maximum of 62% in parallel and 54% in the perpendicular direction. This study could be applicable for reducing the pollution load as well as reusing the spent Cr from discharged waste liquor.
Experimental Investigation of Convection Heat Transfer in a Helical Coil and Shell Heat Exchanger and Drag Reduction by Guar Gum
Abstract
The prime motive of this experimental study is to design a helical coil and shell heat exchanger and analyzing thermal performance based on convection heat transfer. Then, a polysaccharide, guar gum is used to lessen the drag force of cold water in helical pipe inside the heat exchanger, which ultimately lowers the amount of pumping power needed. The shell is made by rolling a square sheet and tube is formed by bending of straight pipe. Then, they are joined by spot welding to fabricate the complete heat exchanger. The rate of flow of cold fluid (tube side) is varied keeping the hot fluid flow rate (shell side) constant. Outlet and inlet temperatures of hot and cold fluids are measured to derive the heat transfer rate and overall convection heat transfer coefficient of cold fluid. Reynolds number and Nusselt number are estimated as two effective parameters of convection heat transfer. Heat transfer rate, overall heat transfer coefficient, Nusselt number and Reynolds number all are noticed to increase gradually with the rise in flow rate of cold fluid. Then, three different concentrations (100 ppm, 250 ppm and 500 ppm) of guar gum solution are used as cold fluid in tube of heat exchanger. The amount of pressure drop in tube found lower than the pure water for same flow conditions. So, mixing of guar gum into water decreases drag force in pipeline and lowers the power required to pump fluids through heat exchanger?s tubes that saves pumping cost. Maximum drop in pressure (50%) observed for maximum concentration.
Opportunities and Challenges for Bangladesh's Clothing Industry in the Circular Economy
Abstract
This study concentrated on the following elements and problems of circular economy in the garment sector. The outcomes of this research work unveil that many barriers emerge concerning a considerable number of circular economy performance indicators. True, many enterprises are new or have recently moved to these models, which need substantial initial investment and a considerable length of time before they begin to enjoy the results, as we have seen in the cases analyzed. From the poll results, we learned that the primary roadblocks are inappropriate worker rights, a lack of knowledge, a lack of skilled workers, a lack of training, a lack of using natural resources, and more. At least one group member identified a technological barrier as the most significant issue. Then there is the issue of cost, which is a major one. Some cited unskilled labor as one of the most pressing concerns. While collecting data, we noticed a trend showing that, increasingly, manufacturing facilities are favoring greener practices. We can also deduce that improved implementation of the circular economic model is possible if all of us, consumers and producers alike. Healthier air and water would improve people's health and standard of living, and reducing pollution worldwide would have a similar effect.
DEVELOPING ANALYSIS TO FULFILL THE PETROLEUM DEMAND OF BANGLADESH USING CRUDE OIL REFINING PROCESS IN THE MOST ECONOMICALLY EFFICIENT MANNER
Abstract
In Bangladesh, from the very beginning fuel demand is depended on refined oil import process. Instead, importing crude oil and refining with our own process capacity that reduce cost at a greater extent. A crude refinery plant with according work capacity can save millions of dollars of money that is currently being spent from Foreign Exchange Reserves. Obvious aim of this analogy. To meet this breach between demand and supply, a particular analogy should be developed with all the crude available to import for Bangladesh. Tracing the demand level of particular user grade fuel of previous years, upcoming yearly fuel demand can be estimated. Another big problem in this field is the supply chain management of the crude oil itself. Depending on global, political, environmental, economical, geological and other aspects can vary the industrial quality and supply quantity in almost no matter of time. So in this very uncertain but important field a reliable process of analysis is a demand of time. To develop an analogy, country demand, management and storing capacity, refined oil import value, mass oil import transportation should be considered. Crude refine ability, processing, availability, relevant costing and profitability are the fundamental base for this analysis. Thus with any situation of demand and supply crude in hand, an organized process of analysis is ready to bring back the supply demand synergy. Developing an analogy to fulfill the petroleum demand of Bangladesh using crude oil refining process in the most economically efficient manner. Diesel is the most popular petroleum fuel in our country, with demand increasing rapidly each year. The present demand for diesel is roughly 5 million tons per year (2018-19 financial year). Refinery production supplements total demand to some extent, but there is still a substantial imbalance between supply and demand of roughly 3.5 million tons per year, which will eventually expand on different time perspective. In fact, there will be enough market demand to warrant the consideration of more refining plants in the future. There are two grades of gasoline in the local market: petrol and octane, with a combined demand of roughly 550 thousand. The local sources can eventually can cope up with this amount of supply. For sudden change of supply or demand, the analysis still works to maintain a perfect match. As to visualize a financial impact, this process reduces 12 crore BDT for 100 barrels crude oil processing in a financial year. The petroleum sector is regarded as one of the most vulnerable sectors of the economy. Macroeconomic indicators are very sensitive to the price of petroleum products. Our country's current petroleum economy is heavily reliant on imports. Since no refining facilities have been built since the country born, the supply-demand mismatch has grown exponentially. According to the findings of this techno-economic study, the impact of a refinery on the Bangladeshi economy is beneficial. Not only will it supplement the country's fuel need, but it will also reduce import reliance and provide job opportunities, both directly and indirectly, adding considerable impact to the national economy. They have a direct influence on the plant's product pattern and profitability, thus they must be properly picked to maximize the output. The current analysis may be enhanced by assessing the various crude oils on the market for profitability and also by modifying the process layout.
Abstract
Nowadays, manufacturers fight to develop flashy cars without compromising safety. The most important aspect of high-speed vehicles lies in its braking system. As a result, several types of research are ongoing to enhance the disc brake quality. Brake discs often use grey cast iron because of its high friction properties and low cost of production, despite of its low level of corrosion and wear resistance properties. In order to solve this issue, several investigations are being undertaken on brake discs for different materials. A steady state thermal analysis has been carried out of a disc brake made of carbon-carbon composites and aluminum silicon carbide metal matrix composites. The materials are selected for dissipating heat at a very rapid rate. For improving the brake stability, optimization of heat transfer rate is a major issue. In this analysis, the temperature fields of the disc are evaluated for one second of braking time using a steady state thermal analysis. The front face of the model is heated to a temperature of 80?C. A convection load between 22?C and 80?C is applied to the inner surface for 1 second. The whole FEA analysis of the rotor is carried out on ANSYS 2021 R1. From the analyses, it is found that the rotor made of carbon-carbon composite performs better than the aluminum-silicon carbide MMC fabricated rotor. Keywords: Braking system, Heat transfer, Rotor analysis, ANSYS design modeler
Fat Liquor from Extracted Oil from Aphanamixis polystachya Seeds for Leather Production
Abstract
Please find the paper attached.
Supplier Selection Based on Multi-criteria for Multi-product: A Case Study
Abstract
Now-a-days, owing to the development of information technology and the removal of trade barriers, the supplier selection issue is becoming increasingly popular. A sound supplier selection decision today can prevent a host of problem tomorrow. Supplier selection problems with numerous criteria are examples of the multi-criteria decision-making problems (MCDMs), which are highly challenging to solve. The purpose of this study is to select best suppliers using an MCDM technique considering few specific criteria. In this study, a Technique for Order Performance by Similarity to Ideal Solution (TOPSIS) method utilized to tackle a multi-supplier selection problem considering multi-criteria for multi-product. The different criteria considered to select the suppliers are cost, products quality, innovation and development capability, delay in delivery, delivery capability and flexibility, and lead time of the suppliers. The applicability of proposed method is validated by a case study on a transformer company named Energypac Engineering Ltd., Dhaka, Bangladesh. The findings obtained from the implementation show the applicability and efficiency of the proposed approach. The current study is a cutting-edge investigation that makes use of the TOPSIS method to resolve the supplier selection issue. This research not only clearly advances methodological selection of the best suppliers, but it can also be used by businesses as a decision-making tool and a management guide.
Effect of saline water in beamhouse and wet-end processing in leather manufacturing
Abstract
Please the attachment
Energy, Economic, and Environmental benefit Analysis of organic fraction of MSW through anaerobic digestion technology in Bangladesh
Abstract
MSW management is one of the main challenges of developing countries like Bangladesh as it is created an environmental problem. The purpose of this paper is to generate MSW generation as well as electricity generation potential from it in Bangladesh for several years through anaerobic digestion (AD) technology. The economic feasibility of the proposed anaerobic digestion project is analyzed by means of net present value (NPV), payback period (PBP), and Levelized cost of energy (LCOE). The NPV of the project is 54760.67 million US$. Additionally, the IPBP of the projects is 9.78 years. The LCOE of electricity generation is 0.07 $/kWh. The economic feasibility of the proposed anaerobic digestion project is analyzed by means of net present value (NPV), payback period (PBP), and Levelized cost of energy (LCOE). It was found that after 20 years of projects (2023 to 2042), the MSW generation rate is about 61.81 Mt/year which is capable to produce 4365.35 MW/year. The NPV of the project is 54,760.67 million US$. Additionally, the IPBP of the projects is 9.78 years. The LCOE of electricity generation is 0.07 $/kWh. On the other hand, the reduction of the CO2 emission footprint of the projects is 150.09 Mt through the projects.
Assessment of an Optimum Off-grid Hybrid Energy System for Electrification in a Rural Area of Bangladesh
Abstract
It is not economically feasible and effective to extend central power line to the remote islands. Isolated hybrid energy systems can be an alternate approach for electrification in such area. In this study a hybrid system is developed for electricity generation in an off grid rural area called Sonadia island, Bangladesh (21?30.1'N, 91?53.5'E). An investigation into the technological and financial viability of different configurations of hybrid energy designs is carried out. and an optimum system is opted based on low cost of energy, net present cost and low emissions. The optimal configuration comprises PV Panel/Diesel/Battery. The optimized setup has Cost of Energy of 0.411 $/kWh and Net Present Cost of $ 437,633. When compared to the grid, diesel the optimal system emits less than 45% and 74% of each, respectively. HOMER simulation is employed to conduct the techno-economic study of the proposed system.
Mechanical Characterization of Date Palm Rachis Fiber Reinforced Epoxy Composite
Abstract
Nowadays more and more research is being carried out to find new environment-friendly, biodegradable, and sustainable materials. These researches include investigating environment-friendly materials like natural composite materials, hybrid composite materials, and other sustainable hybrid materials. Continuous research is being carried out to find alternative reinforcement and matrix systems that can match the performance of the existing system and is more environment-friendly. An epoxy-based composite material was prepared and reinforced with Date Palm rachis fiber using the hand lay-up method. The tensile strength, flexural strength, and impact strength were investigated in this work. The flexural strength was investigated using the three-point bending method and the material had an average flexural strength of 43.242 MPa. The impact test was carried out on two types of specimens with the fibers laid up across the length of the specimen and the width of the specimens. The specimens with fibers laying across the length of the specimens had an impact strength of 224.95 kJ/m2 and the specimens with fibers laying across the width of the specimens had an impact strength of 127.26 kJ/m2. The tensile strength of the material was investigated using a Universal Testing Machine and the material had an average tensile strength of 42.11 MPa.
Abstract
The stresses in single-lap bonded joints are highest at the edges, where failure frequently originates, and lowest at the center. The stress concentration at the ends of a bonded lap joint is influenced by the relative stiffness of the adherend and adhesive used. The stress concentration is smaller and the joint strength may be increased the less stiff the adhesive used in the bond line for a particular adherend. With this technique, high joint strength can be attained. Adhesive joints have been used in a lot of investigations in the past. Numerous industries, including the automotive and aerospace sectors, conduct in-depth studies to ascertain how adhesive joints affect lap bonding. It has also been discovered that when bi-adhesive is utilized in a lap joint rather than mono adhesive, more uniform stress can be obtained. Bi-adhesive was applied with a firm adhesive in the overlap's center and a low modulus adhesive at its edges, which were expected to undergo stress concentrations. A concentrated force was delivered to one side of the entire portion, which had one side fixed. The result shows that the stiffer adherend has higher strength. Through finite element modeling, the rise in apparent lap-shear strength was qualitatively predicted.
Numerical Analysis of the Rear Wing Mount of a Formula 1 Type Car for Material Selection
Abstract
In F1-type racing cars, there is a special type of mounting system for the rear wing and it is the main load-carrying component of the wings that transfer the aerodynamic force to the main structure. This type of mounting is called F1-type rear wing mounting. Wings are mounted on endplates and endplates are connected to the main load-carrying structure. In this analysis, an effort has been given to select proper material with lower weight for the endplates of a formula F1 student vehicle. Aerodynamic forces for longitudinal air flow are considered as the load on the wing and the endplate. Various materials including fiber-reinforced composites are considered for the endplate to identify the proper material for the endplate which would show minimum weight with acceptable deformation and stress. The thickness of the endplate is considered identical for all materials. Aerodynamic forces are also kept constant for all the systems made of different materials. The deformation, weight and equivalent stress of the simple endplates were analyzed. Results show that the Epoxy-Carbon Fiber Unidirectional 395 GPa composite appeared to be the suitable one in terms of weight, deformation and maximum equivalent stress. Using this material, the weight of the endplates can be reduced by 80.38% and 44.41% compared to the steel and aluminum endplates respectively.
Mechanical behavior of sandwich structure made of perlite foam core and JFRP skin
Abstract
In this work, novel sandwich structures have been developed based on perlite/sodium silicate foam as core and jute fiber reinforced epoxy polymer composite (JFRP) as skin. The main objective is to fabricate the sandwich composites and investigate the mechanical behavior of the composites for varying core densities. Perlite/sodium silicate foam cores were consolidated by mixing with the sodium silicate solution. A mold was used to compact the mixer of the perlite and sodium silicate by hand pressing and the wet compact was dried for 24 hours in an electric oven for curing. The hand lay-up process was adopted to fabricate the JFRP. The sandwich formation was done by attaching JFRP skins to both sides of the foam cores. The flexural and compression tests were performed and the results were analyzed in terms of core density. The findings show that the sandwich structures made of high-density foam cores showed enhanced mechanical properties. The flexural and compressive strength increased by 71.75% and 211.86% respectively due to an increase in density of 9.26%. Analysis of the failure behavior during flexural tests indicates that the failure initiates at the core of the sandwich structures showing the direction for the future improvement of developed composites.
Abstract
The electrical efficiency of the PV panel depends on the material of the panel and its surface temperature. With the rise of surface temperature, the electricity generation decreases. Various cooling methods have been applied to decrease the surface temperature of the PV panel. This article experimentally investigates the performance of a PV panel by embedding PCM on its back and flowing water through the copper pipe which is incorporated inside the PCM to absorb the heat from it. As the surface of the PV panel heats up, PCM absorbs the heat and some of this heat is carried away by the flowing water. The surface temperature of the PV/T/PCM system on an average was 1.725 0C lower than that of conventional PV panel. The electrical efficiency of the PV/T/PCM system increased by 2.33% than conventional PV panel. The highest thermal efficiency of the PV/T/PCM obtained was 54.99%. It has been observed that the incorporation of PCM in PV panel could bring a significant improvement providing higher electrical efficiency and also thermal efficiency.
Thermal Performance Evaluation of a Double Tube Ground Coupled Heat Exchanger in the Climate of Bangladesh
Abstract
The ground-coupled heat exchanger (GCHE) is used in space heating and cooling systems to exchange heat with ground soil as a heat source/sink to reduce energy consumption. An experimental investigation is performed in this work to assess the thermal performance of a double tube ground coupled heat exchanger in the climate condition of Bangladesh. A double tube heat exchanger is fabricated using two PVC pipes of different diameter and inserted into 9.14 m depth of the ground. To measure the performance of the heat exchanger, water is circulated through the heat exchanger and temperatures and flow rate of the circulated water are measured. By altering the flow rate, the heat exchanger's rate of heat transfer can be determined. For a period of 12 hours, the water flow rates were 3 lit/min and 5 lit/min. The experiment shows that a flow rate of 3 lit/min gives a higher heat transfer rate per unit length than a flow rate of 5 lit/min. The average rate of heat transfer for the double tube GCHE was 82.36 W/m and 93.28 W/m for the flow rate of 5 lit/min and 3 lit/min, respectively, for the duration of 12 hours.
Experimental Investigation on Heat Transfer through the Roof of Air-Conditioned and Non Air-Conditioned Rooms
Abstract
Building energy consumption in Bangladesh is increasing day-by-day as a result of the increased use of air conditioners. To reduce air conditioning energy consumption, it is required to use energy-efficient building envelopes and properly sized air conditioners. In this respect, it is required to know about the time at which indoor and outdoor air temperatures, and roof surface temperature become peak and heat transfer through building envelopes, especially roofs. The peak indoor air temperature and thermal condition of the roof vary with the indoor air temperature of a room. These data are not available for the Khulna district of Bangladesh. So, the present work has focused on the investigation of such data for air-conditioned room maintained at 25?C and non air-conditioned room for a typical day in June 2022. From the research work, it is found that the indoor air temperature of the non air-conditioned room reaches peak value at the evening which is higher than that of the outdoor air temperature. As the temperature of indoor air becomes high enough, severe discomfort is felt in rooms on the top floor of the building. The maximum outside surface temperature of the roof occurs at noon for both types of rooms but this maximum temperature for the non air-conditioned room is higher than that of the air-conditioned room. On the other hand, the peak value of the inside surface temperature of the roof is found in the evening and this value for the air-conditioned room is higher than that of the non air-conditioned room. Due to maintaining a lower temperature by air conditioners, the peak roof heat gain for the air-conditioned room becomes more than 3 times higher relative to the peak roof heat gain of the non air-conditioned room.