8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING最新文献

{"title":"Numerical study of a crossflow heat exchanger to investigate thermal performance using nanofluids","authors":"Jaed Al Nahian, P. Pandit, M. Mamun","doi":"10.1063/1.5115927","DOIUrl":"https://doi.org/10.1063/1.5115927","url":null,"abstract":"In this study, conjugate heat transfer between solids and fluids has been analyzed for a cross flow rectangular shaped microchannel heat exchanger. Three different nanofluids have been used such as CuO-water, Al2O3-water and Al2O3-ethylene glycol to investigate the effect of changing nanoparticles volume fraction as well as, effect of changing the base fluid at constant temperature. Volume fraction has been varied from 0.5% to 4%. These nanofluids have been widely used in compact heat exchangers, micro reactors, automotive radiators etc. for their exhibition of larger thermos-physical properties than conventional fluids due to presence of nanosized particles in them which enhance heat transfer. It has been observed that changing the base fluid has had a much significant effect than changing the nanoparticle. Heat transfer coefficient, pressure drop and pumping power requirement have been investigated in terms of varying nanoparticles volume fraction and Reynolds number. In addition, different characteristics such as isotherms, channel wall temperature have been graphically shown.In this study, conjugate heat transfer between solids and fluids has been analyzed for a cross flow rectangular shaped microchannel heat exchanger. Three different nanofluids have been used such as CuO-water, Al2O3-water and Al2O3-ethylene glycol to investigate the effect of changing nanoparticles volume fraction as well as, effect of changing the base fluid at constant temperature. Volume fraction has been varied from 0.5% to 4%. These nanofluids have been widely used in compact heat exchangers, micro reactors, automotive radiators etc. for their exhibition of larger thermos-physical properties than conventional fluids due to presence of nanosized particles in them which enhance heat transfer. It has been observed that changing the base fluid has had a much significant effect than changing the nanoparticle. Heat transfer coefficient, pressure drop and pumping power requirement have been investigated in terms of varying nanoparticles volume fraction and Reynolds number. In addition, different characterist...","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"202 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121112495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of wind pressure coefficients on CTBUH standard high-rise buildings in CFD simulations","authors":"Tanvir Chowdhury, Quamrul Islam","doi":"10.1063/1.5115953","DOIUrl":"https://doi.org/10.1063/1.5115953","url":null,"abstract":"At present with the fast growth rate of population constructing high-rise buildings has been a common trend for many urban communities, so it is important to analyze wind pressure around and over these high-rise structures. CFD analysis is an effective way to understand this, in which CTBUH (Council on Tall Buildings and Urban Habitat) standard high-rise building has been a recognized model to validate and calibrate high-rise building models. As it may, less work has been directed to study of airflow around CTBUH standard high-rise building to geometric and computational parameters in CFD analysis. In this investigation is therefore intended to fill this gap by analyzing effects of various parameters like turbulence model, approaching-flow speed and grid type on wind pressure coefficients over CTBUH structures. Wind pressure coefficients around CTBUH models subjected to three wind directions were numerically analyzed for validating the correctness and effectiveness of numerical model. In conclusion acquired results can help structural engineers to choose empirical geometric and computational parameters in anticipating wind pressure distribution against high-rise buildings.At present with the fast growth rate of population constructing high-rise buildings has been a common trend for many urban communities, so it is important to analyze wind pressure around and over these high-rise structures. CFD analysis is an effective way to understand this, in which CTBUH (Council on Tall Buildings and Urban Habitat) standard high-rise building has been a recognized model to validate and calibrate high-rise building models. As it may, less work has been directed to study of airflow around CTBUH standard high-rise building to geometric and computational parameters in CFD analysis. In this investigation is therefore intended to fill this gap by analyzing effects of various parameters like turbulence model, approaching-flow speed and grid type on wind pressure coefficients over CTBUH structures. Wind pressure coefficients around CTBUH models subjected to three wind directions were numerically analyzed for validating the correctness and effectiveness of numerical model. In conclusion acquir...","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125522225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-Newtonian shear thinning effect on natural convection flow over an isothermal elliptical cylinder","authors":"P. Nag, M. Molla, Md.Anwar Hossain","doi":"10.1063/1.5115860","DOIUrl":"https://doi.org/10.1063/1.5115860","url":null,"abstract":"In this paper, laminar natural convection flow of Newtonian and non-Newtonian (shear thinning case only) fluid surround an isothermal horizontal cylinder of elliptic cross section has been studied numerically. To characterize the non-Newtonian fluid, a modified power-law viscosity model has been employed. The boundary layer equations governing the flow are transformed into a non-dimensional form and the resulting equations are reduced to a convenient form which are solved numerically by an efficient implicit finite difference method. Numerical results are presented for two significant physical quantity such as the local skin friction coefficients and the rate of surface heat transfer (i.e. the local Nusselt number) as a function of the eccentric angle of an elliptical configurations with different aspect ratio and for different orientation such as blunt and slender. The local skin friction is found to be higher for Newtonian fluid than that of the shear thinning fluid. Furthermore, the total heat transfer rate becomes higher for elliptical cylinder with slender orientation than that of the blunt orientation in the fluids of interest.In this paper, laminar natural convection flow of Newtonian and non-Newtonian (shear thinning case only) fluid surround an isothermal horizontal cylinder of elliptic cross section has been studied numerically. To characterize the non-Newtonian fluid, a modified power-law viscosity model has been employed. The boundary layer equations governing the flow are transformed into a non-dimensional form and the resulting equations are reduced to a convenient form which are solved numerically by an efficient implicit finite difference method. Numerical results are presented for two significant physical quantity such as the local skin friction coefficients and the rate of surface heat transfer (i.e. the local Nusselt number) as a function of the eccentric angle of an elliptical configurations with different aspect ratio and for different orientation such as blunt and slender. The local skin friction is found to be higher for Newtonian fluid than that of the shear thinning fluid. Furthermore, the total heat transfer...","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122877539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Process analysis and gasification of rice husk by using downdraft fixed bed gasifier","authors":"M. E. Hoque, F. Rashid, S. Aziz, M. Rahman, P. Das","doi":"10.1063/1.5115951","DOIUrl":"https://doi.org/10.1063/1.5115951","url":null,"abstract":"The use of fossil fuels has great impact on environment and energy security problems. Besides, the rising cost of fuel oil compelled the industry to search for alternative fuels, and biomass in general and rice husks in particular are considered a suitable candidate. Bio energy has significant potential contribution for sustainable energy systems, especially when converted to modern energy carriers such as electricity, gaseous or liquid fuels. Rice is cultivated in more than 75 countries in the world. The rice husk is the outer cover of the rice and on average it accounts for 20% of the paddy produced, on weight basis. The worldwide annual husk is about 80 million tons with an annual energy potential of 1.2∼109 GJ corresponding to a heating value of 15 MJ/kg. Maximum rice husk produced by milling process of rice mills in Bangladesh usually burned in the mill boilers to produce process heat for parboiling of paddy rice and excess husk are sold to the market as fuel for cooking purposes and a considerable portion is misused. Therefore, syngas from rice husk can be produced as an auspicious source of energy. It can be used to generate heat and power like natural gas, synthesize other chemicals and liquid fuels, or produce H2. One of the promising approaches for syngas production from biomass is downdraft fixed bed gasification among the several approaches till developed. Optimization of operating conditions (combustion zone temperature, reaction zone temperature, intake air temperature, humidity of intake air and air flow rate) can give a satisfactory result for the quality syngas production. In this paper rice husk was used as potential biomass feed stocks. The moisture content of the feed material is less than 10% on weight basis and consumption rate of rice husk is 3.62 kg/h. Temperature inside the reaction zone (970∼994) K, primary air flow rate 2.7 m3/h, humidity of outside air (45∼50%) and exit temperature of the producer gas (140∼160)°C were measured. This paper gives an optimistic operating condition for quality syngas production.","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134541671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A simplified one-equation elliptic-relaxation model","authors":"Xiaoqing Tian, Mizanur Rahman, H. Pan, A. Islam","doi":"10.1063/1.5115888","DOIUrl":"https://doi.org/10.1063/1.5115888","url":null,"abstract":"A simplified version of a one-equation R = Cμk2/ϵ turbulence model with elliptic relaxation, formulated by Elkhoury [4] containing explicitly constant coefficients, is proposed that accounts for the distinct effects of low-Reynolds number (LRN) and near-wall turbulence. In the simplified model, coefficients and functions are constructed such as to preserve the anisotropic characteristics of turbulence encountered in nonequilibrium flows. The constant-dependent sensitivity of characteristic length scale associated with the elliptic relaxation function is reduced to an extent. Unlike the Elkhoury model, it requires the elliptic equation for the elliptic relaxation parameter fR with a source term 1.0 (one) to be solved in conjunction with the R-equation model. A near-wall damping function is introduced to relax the viscous length-scale coefficient of the elliptic relaxation model. This incentive approach stems from the combination of wall-viscous (LRN) and wall-blocking (nonlocal) effects. The simplified mod...","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133048079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards an improved pyrolysis system: Integrating solar energy based pre-heating system","authors":"Md. Washim Akram, T. Mondal, Md. Touhidur Rahman, A. Rahim, R. Mursalin","doi":"10.1063/1.5115931","DOIUrl":"https://doi.org/10.1063/1.5115931","url":null,"abstract":"Thermo-chemical conversion process such as gasification and pyrolysis has proven as a potential option to utilize renewable energy. In conventional pyrolysis process, feed material in the reactor i...","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"208 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115904255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat transfer enhancement in shell and tube heat exchanger by using Al2O3/water and TiO2/water nanofluid","authors":"Md. Rahmat Ullah, Tanvir Muhammad Ishtiaq, M. Mamun","doi":"10.1063/1.5115925","DOIUrl":"https://doi.org/10.1063/1.5115925","url":null,"abstract":"Nanofluids, potential heat transfer fluid with enhanced thermophysical properties are recently being experimented in different heat transfer device for better performance. Heat transfer characteristics of γ-Al2O3/water and TiO2/water nanofluids has been numerically investigated in a shell and tube heat exchanger under turbulent flow condition. The effects of Reynolds number, volume concentration of suspended nanoparticles, and particle type on the heat characteristics has been investigated. Based on the results, addition of naoparticles to the base fluid causes the significant enhancement of heat transfer characteristics. For γ-Al2O3/water maximum improvement in convective heat transfer coefficient is 41.8% while TiO2/water shows maximum 37% increment. The introduction of nanoparticle incorporates more viscosity than base fluid which eventually increases the pressure drop, but the drop has not been found to be considerably high.Nanofluids, potential heat transfer fluid with enhanced thermophysical properties are recently being experimented in different heat transfer device for better performance. Heat transfer characteristics of γ-Al2O3/water and TiO2/water nanofluids has been numerically investigated in a shell and tube heat exchanger under turbulent flow condition. The effects of Reynolds number, volume concentration of suspended nanoparticles, and particle type on the heat characteristics has been investigated. Based on the results, addition of naoparticles to the base fluid causes the significant enhancement of heat transfer characteristics. For γ-Al2O3/water maximum improvement in convective heat transfer coefficient is 41.8% while TiO2/water shows maximum 37% increment. The introduction of nanoparticle incorporates more viscosity than base fluid which eventually increases the pressure drop, but the drop has not been found to be considerably high.","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114410996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Temperature dependent mechanical properties of inter-metallic compounds in nano-solder joints","authors":"M. Billah, R. I. Siddiquee, M. Motalab","doi":"10.1063/1.5115965","DOIUrl":"https://doi.org/10.1063/1.5115965","url":null,"abstract":"SnAgCu (SAC) alloys has become the topic of interest in recent days, as it shows great potential to be alternate to lead-based solders, the use of which is being discontinued for environmental issues. Intermetallic compounds (IMC) form in the solder joints which reduces the strength and other properties thus reducing the reliability of microprocessor components. To investigate this behavior, intermetallic compounds were modeled at nanoscale. Properties of three intermetallic compounds were investigated which are Ag3Sn, Cu3Sn and Cu6Sn5. The variation of mechanical properties the ultimate tensile strength, yield strength and Young’s modulus with the change of temperature were thoroughly observed. Also, the coefficient of thermal expansion was determined for these three different compounds. The mechanical properties of these three compounds were compared to find out which of these poses the greater threat to the solder joints. All the simulations were done by molecular dynamics software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) and the structures of the IMCs were built by VNL (Virtual NanoLab). Molecular dynamics approach was used to model the interaction between molecules under various temperatures.SnAgCu (SAC) alloys has become the topic of interest in recent days, as it shows great potential to be alternate to lead-based solders, the use of which is being discontinued for environmental issues. Intermetallic compounds (IMC) form in the solder joints which reduces the strength and other properties thus reducing the reliability of microprocessor components. To investigate this behavior, intermetallic compounds were modeled at nanoscale. Properties of three intermetallic compounds were investigated which are Ag3Sn, Cu3Sn and Cu6Sn5. The variation of mechanical properties the ultimate tensile strength, yield strength and Young’s modulus with the change of temperature were thoroughly observed. Also, the coefficient of thermal expansion was determined for these three different compounds. The mechanical properties of these three compounds were compared to find out which of these poses the greater threat to the solder joints. All the simulations were done by molecular dynamics software LAMMPS (Large-scale ...","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"24 12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128301185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of sintering profile to achieve highly toughened alumina based ceramic","authors":"U. Salma, M. Hasanuzzaman","doi":"10.1063/1.5115964","DOIUrl":"https://doi.org/10.1063/1.5115964","url":null,"abstract":"Alumina (Al2O3) based ceramics are widely used for making machine parts, high-temperature components, wear-resistant material and biological ceramic due to their high hardness, strength, wear-resistance, and chemical and thermal stability. However, low fracture toughness (KIC∼3.0 MPa.m1/2) inhibit its usage in other potential applications where high toughness is a pre-requisite (e.g. ceramic engine). In an attempt to improve the strength, particularly the fracture toughness, two step sintering process was used. Sintering temperature was optimized based on the results obtained from dilatometer and DSC-TG analysis. X-ray fluorescence (XRF) was used to make compositional analysis of as received raw powders and X-ray Diffraction (XRD) was used to analysis the phase purity and crystallinity for both powder and sintered samples. Microstructure was investigated by using SEM. Hardness and fracture toughness was measured and its correlation with microstructure was investigated. Density was measured by Archimedes method and crystalline density from XRD. Microhardness diamond indenter was used and the diagonal length of indent and the crack lengths were measured by SEM to calculate the Vickers hardness values and fracture toughness, respectively. The maximum fracture toughness was obtained 4.03 MPa.m1/2 for Al2O3 ceramic and the hardness value was 15.97 GPa. Density was found 99.6% of the relative density of Alumina at optimum sintering cycle and the grain size was found 0.38 µm. Thermal expansion coefficient was measured by dilatometer and the calculated value was 7.9×10-6 K-1. The physical properties of the Alumina were good enough and comparable to withstand high temperature applications.Alumina (Al2O3) based ceramics are widely used for making machine parts, high-temperature components, wear-resistant material and biological ceramic due to their high hardness, strength, wear-resistance, and chemical and thermal stability. However, low fracture toughness (KIC∼3.0 MPa.m1/2) inhibit its usage in other potential applications where high toughness is a pre-requisite (e.g. ceramic engine). In an attempt to improve the strength, particularly the fracture toughness, two step sintering process was used. Sintering temperature was optimized based on the results obtained from dilatometer and DSC-TG analysis. X-ray fluorescence (XRF) was used to make compositional analysis of as received raw powders and X-ray Diffraction (XRD) was used to analysis the phase purity and crystallinity for both powder and sintered samples. Microstructure was investigated by using SEM. Hardness and fracture toughness was measured and its correlation with microstructure was investigated. Density was measured by Archimedes m...","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130579587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of ferroelastic mechanical behavior of lanthanum ferrite, LaFeO3","authors":"M. Islam, W. Araki, Y. Arai","doi":"10.1063/1.5115956","DOIUrl":"https://doi.org/10.1063/1.5115956","url":null,"abstract":"The present study investigates the deformation behavior of lanthanum ferrite, LaFeO3 under uniaxial compression. Ferroelastic domains were observed in samples at high temperature etching which was confirmed by scanning electron microscopic observation. XRD patterns of all samples showed characteristics reflection with orthorhombic crystal structure. Uniaxial compression tests were carried out at temperature of 93K, 193K, 293K, 393K, and 553K, at a constant loading rate of 1.0 MPa/s. All samples exhibited non-elastic stress-strain behavior during loading- unloading cycles owing to ferroelasticity. The slope of the stress-strain curves increased with increasing the temperature as well as ferroelastic parameters, initial modulus and loading modulus were increased due to ferroelastic domain switching.","PeriodicalId":423885,"journal":{"name":"8TH BSME INTERNATIONAL CONFERENCE ON THERMAL ENGINEERING","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122308465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}