Vivian González, Liz Esquivel, Elías Espínola, Abdías García, Víctor Burgos, Fabio Coronel, Francisco Gómez, P. Cañete, Luis Gusto, J. Vázquez, Diego González, Rossana Villalba, Jorge H. Kurita
Toxic gasses generated as a result of landfill fire are a big concern to human health, especially in heavily populated urban areas. Such a situation occurred on September 25, 2020, at the country’s main landfill situated in Asuncion city, the most populated urban area in Paraguay. This is a recurrent situation, two days later; another fire started at the same landfill. It took 12 hours to control the fire. This event generated a plume of toxic smoke that spread through the urban area. This caused severe respiratory problems to the citizens living in the surrounding buildings. This work is a case study on the analysis of the smoke plume spreading from this landfill in an eventual fire in different wind directions. The main goal was to conduct computational fluid dynamics CFD simulation to be able to map the risk zone on this surrounding urban area. In order to validate this simulation, it was important to replicate this toxic cloud flow by conducting a computational fluid dynamics CFD simulation and comparing this result with actual data. For this purpose, a satellite image taken on the September 25 of the year 2020 fire event was utilized. A good agreement was observed in this comparison. This validated the boundary conditions of this computational tool. A mesh sensitivity analysis was also carried out to ensure a reliable result was obtained. The city hall as well as the fire departments from the city of Asuncion are now using this map as a guide to better prepare to deal with this toxic smoke by quickly evacuating or notifying residents in the risk zones. The national secretary of emergency is also provided with this map. Future work includes the analysis of not only other landfills but also warehouse or electric power substations where toxic fuel, such as askarel is present in a latent mode. A recent fire at community markets is also on the list of the potential smoke sources to be analyzed. This undergraduate student research paper is a work in progress. More data is being analyzed. The usefulness and practical use of this kind of computational tool are getting the interest of local authorities. This work helps to promote students’ motivation in the field of fluid dynamics. The impact on STEM education was noted in this case study. It is planned to compare other software and schemes to better understand computational tools. Finally, a result comparison between cases is expected to be presented.
{"title":"Fume Flow Analysis Generated From Landfill Fire, A Case Study","authors":"Vivian González, Liz Esquivel, Elías Espínola, Abdías García, Víctor Burgos, Fabio Coronel, Francisco Gómez, P. Cañete, Luis Gusto, J. Vázquez, Diego González, Rossana Villalba, Jorge H. Kurita","doi":"10.1115/imece2022-96178","DOIUrl":"https://doi.org/10.1115/imece2022-96178","url":null,"abstract":"\u0000 Toxic gasses generated as a result of landfill fire are a big concern to human health, especially in heavily populated urban areas. Such a situation occurred on September 25, 2020, at the country’s main landfill situated in Asuncion city, the most populated urban area in Paraguay.\u0000 This is a recurrent situation, two days later; another fire started at the same landfill. It took 12 hours to control the fire. This event generated a plume of toxic smoke that spread through the urban area. This caused severe respiratory problems to the citizens living in the surrounding buildings.\u0000 This work is a case study on the analysis of the smoke plume spreading from this landfill in an eventual fire in different wind directions. The main goal was to conduct computational fluid dynamics CFD simulation to be able to map the risk zone on this surrounding urban area. In order to validate this simulation, it was important to replicate this toxic cloud flow by conducting a computational fluid dynamics CFD simulation and comparing this result with actual data. For this purpose, a satellite image taken on the September 25 of the year 2020 fire event was utilized. A good agreement was observed in this comparison. This validated the boundary conditions of this computational tool. A mesh sensitivity analysis was also carried out to ensure a reliable result was obtained.\u0000 The city hall as well as the fire departments from the city of Asuncion are now using this map as a guide to better prepare to deal with this toxic smoke by quickly evacuating or notifying residents in the risk zones. The national secretary of emergency is also provided with this map.\u0000 Future work includes the analysis of not only other landfills but also warehouse or electric power substations where toxic fuel, such as askarel is present in a latent mode. A recent fire at community markets is also on the list of the potential smoke sources to be analyzed. This undergraduate student research paper is a work in progress. More data is being analyzed. The usefulness and practical use of this kind of computational tool are getting the interest of local authorities.\u0000 This work helps to promote students’ motivation in the field of fluid dynamics. The impact on STEM education was noted in this case study. It is planned to compare other software and schemes to better understand computational tools. Finally, a result comparison between cases is expected to be presented.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128566573","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}
The present work investigates the combined effect of flow rate pattern configuration and the presence of localized passive cooling systems such as heat pipes to improve the thermal performance of an air-cooling system. The combined heat pipe air-cooling system consists of 10 blocks (batteries) arranged in parallel and surrounded by 10 to 11 air passage channels; the blocks are subjected to variable heat generations. Previous studies have shown that air cooling systems do not provide a uniform temperature distribution when loaded with constant heat generation. Three flow configurations were numerically investigated: the U, Z, and I configuration, respectively. A three-dimensional numerical simulation was conducted to solve the continuity, momentum, and energy equations of the working fluid. The numerical model also included the presence of the ten blocks, heat pipe, and related boundary conditions. The heat pipe was modeled as a solid material with high effective thermal conductivity. The results from the three air configurations without the presence of heat pipes depict an increase in the temperature field in blocks 5, 6, 7, 8, and 9 for the Z-configuration; blocks 2, 3, 8, and 9 for the I-configuration; and blocks 3, 4, 5, and 6 for the U-configuration. The I-configurations show a better temperature distribution on the blocks compared with the U and Z configuration. Different flow airflow rates were also investigated to reduce the hot spot temperature fields on the blocks. No significant difference was found in increasing the air mass flow rate. After placing a heat pipe closed to the air channels of the block with a high peak in temperature for the three air cooling configurations, the performance of the air-cooling system improved. The number of blocks with higher spot temperature was reduced to blocks 7 and 8 for Z-configuration, blocks 3 and 8 for the I-configuration and blocks 4 and 5 for the U-configuration. The presence of the heat pipe increased the pressure drop between the inlet and outlet for the three configurations. The results have shown that the U-configuration experienced the lowest pressure drop, and the I-configuration presented the most uniform temperature distributions of the block. The results revealed potential thermal performance improvement by using heat pipes in localized hot spot regions in air cooling systems for Li-Ion batteries or other cooling systems subjected to continuous or intermittent heat generation.
{"title":"Study of Different Flow Configurations and Heat Pipe Combination Effects in Air Cooling Systems","authors":"Gerardo Carbajal","doi":"10.1115/imece2022-97105","DOIUrl":"https://doi.org/10.1115/imece2022-97105","url":null,"abstract":"\u0000 The present work investigates the combined effect of flow rate pattern configuration and the presence of localized passive cooling systems such as heat pipes to improve the thermal performance of an air-cooling system. The combined heat pipe air-cooling system consists of 10 blocks (batteries) arranged in parallel and surrounded by 10 to 11 air passage channels; the blocks are subjected to variable heat generations. Previous studies have shown that air cooling systems do not provide a uniform temperature distribution when loaded with constant heat generation. Three flow configurations were numerically investigated: the U, Z, and I configuration, respectively. A three-dimensional numerical simulation was conducted to solve the continuity, momentum, and energy equations of the working fluid. The numerical model also included the presence of the ten blocks, heat pipe, and related boundary conditions. The heat pipe was modeled as a solid material with high effective thermal conductivity. The results from the three air configurations without the presence of heat pipes depict an increase in the temperature field in blocks 5, 6, 7, 8, and 9 for the Z-configuration; blocks 2, 3, 8, and 9 for the I-configuration; and blocks 3, 4, 5, and 6 for the U-configuration. The I-configurations show a better temperature distribution on the blocks compared with the U and Z configuration. Different flow airflow rates were also investigated to reduce the hot spot temperature fields on the blocks. No significant difference was found in increasing the air mass flow rate. After placing a heat pipe closed to the air channels of the block with a high peak in temperature for the three air cooling configurations, the performance of the air-cooling system improved. The number of blocks with higher spot temperature was reduced to blocks 7 and 8 for Z-configuration, blocks 3 and 8 for the I-configuration and blocks 4 and 5 for the U-configuration. The presence of the heat pipe increased the pressure drop between the inlet and outlet for the three configurations. The results have shown that the U-configuration experienced the lowest pressure drop, and the I-configuration presented the most uniform temperature distributions of the block. The results revealed potential thermal performance improvement by using heat pipes in localized hot spot regions in air cooling systems for Li-Ion batteries or other cooling systems subjected to continuous or intermittent heat generation.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128598444","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}
Dario Méndez Méndez, Vicente Pérez García, Angel Isaac Solorio Alvarado, Juan Manuel Belman Flores, José de Jesús Ramírez Minguela
Vapor compression refrigeration systems (VCR) continue to be the most widely used type of air conditioning system for automobiles, however, they represent high energy consumption and, due to the use of R134a as a refrigerant fluid, they induce a significant environmental impact. Although investigations have increased over the last three decades, alternative automotive air conditioning systems (MACs) are not yet fully developed. Among these opportunities is the replacement of the traditional expansion device used in VCR systems with an ejector which represents low investment costs, lower losses can be achieved during the expansion process, and contribute to the recovery of work in the compressor, this reduction in the work consumption of the MACs produces a lower fuel consumption of the automobile engine. Due to international regulations regarding the use of refrigerants in automotive air conditioning systems, R134a is a fluid that is already being phased out. Before this action, various options were proposed to match or even exceed the energy performance that R134a offered in MACs. One option that emerges from all of them is R445A, especially since it fully complies with the low GWP limit set in the Normative EU-517/2014. In this work, the basic refrigeration cycle (BRC) is modeled and compared to the refrigeration cycle configuration that uses an ejector (EC). Both models were made using R134a and R445A to compare the influence of the ejector and the low GWP refrigerant. The results show that the EC with R445A reaches increases in COP from 4.1 to 15.6%, compared to that obtained in BRC mode, in addition to reducing power consumption in the compressor from 2.7 to 11.3%. On the other hand, when comparing the COP of the EC with R445A and the BRC using R134a, increases of up to 6.3% are observed in favor of R445A and a power requirement of 14.3% less for R445A compared to R134a. In addition, when evaluating the fuel consumption in volume per unit of time, the EC configuration proposed with R445A reduces the fuel required for this system by up to 40.4% for an evaporating temperature of 5°C, in the same way, for the evaporation conditions of 10 and 15°C, lower fuel requirements were obtained between 18.1 and 35.5%, this compared to the base system, R134a in BRC mode. Finally, by varying the condensing temperature in a range from 35 to 55°C, the fuel requirement increased, however, the EC configuration maintained the trend towards savings in the required fuel flow concerning the BRC.
{"title":"Energy and Consumption Fuel Study for a Mobile Air Conditioning System Using Ejector and R445A As a Replacement Alternative for R134a","authors":"Dario Méndez Méndez, Vicente Pérez García, Angel Isaac Solorio Alvarado, Juan Manuel Belman Flores, José de Jesús Ramírez Minguela","doi":"10.1115/imece2022-96223","DOIUrl":"https://doi.org/10.1115/imece2022-96223","url":null,"abstract":"\u0000 Vapor compression refrigeration systems (VCR) continue to be the most widely used type of air conditioning system for automobiles, however, they represent high energy consumption and, due to the use of R134a as a refrigerant fluid, they induce a significant environmental impact. Although investigations have increased over the last three decades, alternative automotive air conditioning systems (MACs) are not yet fully developed. Among these opportunities is the replacement of the traditional expansion device used in VCR systems with an ejector which represents low investment costs, lower losses can be achieved during the expansion process, and contribute to the recovery of work in the compressor, this reduction in the work consumption of the MACs produces a lower fuel consumption of the automobile engine.\u0000 Due to international regulations regarding the use of refrigerants in automotive air conditioning systems, R134a is a fluid that is already being phased out. Before this action, various options were proposed to match or even exceed the energy performance that R134a offered in MACs. One option that emerges from all of them is R445A, especially since it fully complies with the low GWP limit set in the Normative EU-517/2014. In this work, the basic refrigeration cycle (BRC) is modeled and compared to the refrigeration cycle configuration that uses an ejector (EC). Both models were made using R134a and R445A to compare the influence of the ejector and the low GWP refrigerant. The results show that the EC with R445A reaches increases in COP from 4.1 to 15.6%, compared to that obtained in BRC mode, in addition to reducing power consumption in the compressor from 2.7 to 11.3%. On the other hand, when comparing the COP of the EC with R445A and the BRC using R134a, increases of up to 6.3% are observed in favor of R445A and a power requirement of 14.3% less for R445A compared to R134a. In addition, when evaluating the fuel consumption in volume per unit of time, the EC configuration proposed with R445A reduces the fuel required for this system by up to 40.4% for an evaporating temperature of 5°C, in the same way, for the evaporation conditions of 10 and 15°C, lower fuel requirements were obtained between 18.1 and 35.5%, this compared to the base system, R134a in BRC mode. Finally, by varying the condensing temperature in a range from 35 to 55°C, the fuel requirement increased, however, the EC configuration maintained the trend towards savings in the required fuel flow concerning the BRC.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125831953","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}
Compressor operation under off-design conditions generates undesirable instabilities and detrimental effects both on system stability and machine reliability perspectives. The main objective is to provide a suitable approach and proper description of the flow and machine behaviour in the surge inception to reverse flow operating area, yielding valuable data for a deeper understanding of the underlying flow mechanisms, useful for tuning prediction models. A literature review, with a particular focus on the experimental method, test rig layout, and instrumentation when handling with reverse and pulsating flow, is presented. The need for a clear setting of test procedure and key parameters measurements to detect unsteady phenomena under transient conditions, with instrumentation available for field operation and separating compressor behaviour from system response, is specifically addressed. To perform this, the experimental technique is employed and described in detail in this paper, while performance modeling validation, object of parallel studies, will be presented in future publications. The test facility allows the required responsive dynamic measurements; tests cover a broad range of flow rates and two different rotational speeds. The aim is to specifically approach the instabilities sections and characterize the positive slope area, featuring rapid cycles between surge line and zero-flow. The results, presented as pressure and flow fluctuations, play a key role for the simulation of more complex dynamic scenarios. This wide collection of test data is of great value for a further understanding of the phenomenon, the development of reliable surge onset prediction models and control strategies.
{"title":"Experimental Characterization of Surge Cycles in a Centrifugal Compressor","authors":"A. Serena, L. Bakken","doi":"10.1115/imece2022-94747","DOIUrl":"https://doi.org/10.1115/imece2022-94747","url":null,"abstract":"\u0000 Compressor operation under off-design conditions generates undesirable instabilities and detrimental effects both on system stability and machine reliability perspectives.\u0000 The main objective is to provide a suitable approach and proper description of the flow and machine behaviour in the surge inception to reverse flow operating area, yielding valuable data for a deeper understanding of the underlying flow mechanisms, useful for tuning prediction models.\u0000 A literature review, with a particular focus on the experimental method, test rig layout, and instrumentation when handling with reverse and pulsating flow, is presented.\u0000 The need for a clear setting of test procedure and key parameters measurements to detect unsteady phenomena under transient conditions, with instrumentation available for field operation and separating compressor behaviour from system response, is specifically addressed. To perform this, the experimental technique is employed and described in detail in this paper, while performance modeling validation, object of parallel studies, will be presented in future publications.\u0000 The test facility allows the required responsive dynamic measurements; tests cover a broad range of flow rates and two different rotational speeds. The aim is to specifically approach the instabilities sections and characterize the positive slope area, featuring rapid cycles between surge line and zero-flow.\u0000 The results, presented as pressure and flow fluctuations, play a key role for the simulation of more complex dynamic scenarios. This wide collection of test data is of great value for a further understanding of the phenomenon, the development of reliable surge onset prediction models and control strategies.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114238268","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}
Recent energy crisis has forced researchers to design fuel-efficient automobiles, where one of the main critical changes is to reduce aerodynamics drag created by fluid friction. At high speed, aerodynamics drag, especially the pressure drag, creates a substantial backward force, and hence, unwanted excess fuel is consumed to counterbalance this dragging effect, which hinders designing fuel-efficient automobiles. Hence, to mitigate this pressure drag, here in this work, numerical analyses have been done (i) to examine drag coefficient changes through incorporating aerodynamic vents at the front, at the rear, and both front and rear on the automobiles, (ii) to reduce drag force by utilizing exhaust gas to fill the low-pressure vortex, (iii) to investigate the effect of wheels on the overall drag resistance of the model. The ANSYS™ 2020 R1 Fluent module is used to perform this numerical simulation. Appreciable improvement on drag reduction can be found by incorporating above mentioned modifications on racing car body configuration.
{"title":"Numerical Investigation on Aerodynamic Performance of a Racing Car by Drag Reduction","authors":"M. Hassan, M. Hassan, Mohammad Ali, M. Amin","doi":"10.1115/imece2022-94495","DOIUrl":"https://doi.org/10.1115/imece2022-94495","url":null,"abstract":"\u0000 Recent energy crisis has forced researchers to design fuel-efficient automobiles, where one of the main critical changes is to reduce aerodynamics drag created by fluid friction. At high speed, aerodynamics drag, especially the pressure drag, creates a substantial backward force, and hence, unwanted excess fuel is consumed to counterbalance this dragging effect, which hinders designing fuel-efficient automobiles. Hence, to mitigate this pressure drag, here in this work, numerical analyses have been done (i) to examine drag coefficient changes through incorporating aerodynamic vents at the front, at the rear, and both front and rear on the automobiles, (ii) to reduce drag force by utilizing exhaust gas to fill the low-pressure vortex, (iii) to investigate the effect of wheels on the overall drag resistance of the model. The ANSYS™ 2020 R1 Fluent module is used to perform this numerical simulation. Appreciable improvement on drag reduction can be found by incorporating above mentioned modifications on racing car body configuration.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"14 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131752203","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}
Ashutosh Pandey, Bharath Madduri, C. Perng, Chiranth Srinivasan, Sujan Dhar
Electric vehicles are becoming increasingly common due to environmental needs. Due to this, efficiency in design process of electric motors (E-motor) is becoming critical in the industry. To assess performance capabilities for an E-motor, thermal predictions are of utmost consequence. This study describes a computational method based on unsteady Reynolds-averaged Navier-Stokes equations that resolves the gas-liquid interface to examine the unsteady multiphase flow and heat transfer in a concentrated winding E-motor. The study considers all important parts of the motor i.e., coils, bobbins, stator laminate (yolk), rotor laminate, magnets etc. The study highlights the ease of capturing complex and intricate flow paths with a robust mesh generation tool in combination with a robust high-fidelity interface capturing VOF scheme to resolve the gas-liquid interfaces. Results obtained show the dominant processes that determine the oil distribution to be the centrifugal force from rotation of the rotor, the flow rate of oil injected in the stator assembly as well as in the rotor assembly and gravity. A novel heat transfer approach (mixed time-scale coupling) is used to solve for the temperatures in the stator and rotor solids. The approach first requires achieving a quasi-steady flow solution before initiating heat transfer calculation for faster turnaround times. The approach separates the conjugate heat transfer calculation into a fluid heat simulation and a solid heat simulation while setting up a communication method to exchange the thermal boundary conditions between the two simulations. This study also considers the anisotropic nature of thermal conductivities resulting from the wound-around arrangement of the coils and the laminate nature of stator/rotor laminates in the assignment of the thermal conductivities of these solids. Results of thermal simulation show the solid temperatures to be in direct correlation with the oil distribution near those solids. This computational study was validated by comparing the computed and measured temperatures at specified locations on the coils and good agreements with experiments were found.
{"title":"Multiphase Flow and Heat Transfer in an Electric Motor","authors":"Ashutosh Pandey, Bharath Madduri, C. Perng, Chiranth Srinivasan, Sujan Dhar","doi":"10.1115/imece2022-96801","DOIUrl":"https://doi.org/10.1115/imece2022-96801","url":null,"abstract":"\u0000 Electric vehicles are becoming increasingly common due to environmental needs. Due to this, efficiency in design process of electric motors (E-motor) is becoming critical in the industry. To assess performance capabilities for an E-motor, thermal predictions are of utmost consequence. This study describes a computational method based on unsteady Reynolds-averaged Navier-Stokes equations that resolves the gas-liquid interface to examine the unsteady multiphase flow and heat transfer in a concentrated winding E-motor. The study considers all important parts of the motor i.e., coils, bobbins, stator laminate (yolk), rotor laminate, magnets etc. The study highlights the ease of capturing complex and intricate flow paths with a robust mesh generation tool in combination with a robust high-fidelity interface capturing VOF scheme to resolve the gas-liquid interfaces. Results obtained show the dominant processes that determine the oil distribution to be the centrifugal force from rotation of the rotor, the flow rate of oil injected in the stator assembly as well as in the rotor assembly and gravity. A novel heat transfer approach (mixed time-scale coupling) is used to solve for the temperatures in the stator and rotor solids. The approach first requires achieving a quasi-steady flow solution before initiating heat transfer calculation for faster turnaround times. The approach separates the conjugate heat transfer calculation into a fluid heat simulation and a solid heat simulation while setting up a communication method to exchange the thermal boundary conditions between the two simulations. This study also considers the anisotropic nature of thermal conductivities resulting from the wound-around arrangement of the coils and the laminate nature of stator/rotor laminates in the assignment of the thermal conductivities of these solids. Results of thermal simulation show the solid temperatures to be in direct correlation with the oil distribution near those solids. This computational study was validated by comparing the computed and measured temperatures at specified locations on the coils and good agreements with experiments were found.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132348884","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}
The fossil fuel depletion and environmental pollution are global challenges. Hydrogen is one of the most abundant elements on earth. Recently, scientists and researchers are investigating water splitting to produce oxy-hydrogen for internal combustion engines. Several studies have been published where hydrogen was used to generate electricity. The proton exchange membrane fuel cell (PEMFC) is an alternative energy resource for future electric vehicles. The reaction of PEMFC includes hydrogen molecules splitting as hydrogen ions and electrons on the anode whereas proton meet with oxygen and electrons and form water and release heat on the cathode. There are several processes involved in heat generation in PEMFC such as resistance in current flow, entropic heat reaction, and irreversibility of the electrochemical reactions. The generated heat in PEMFC is removed through cooling channels. The heat transfer rate depends on thermal properties. The design of the such as polymer electrolyte membrane, catalyst layer, gas diffusion layer, and electrodes have different thermal properties which influence heat transfer. Proper thermal management is critical part of PEMFC operation. Because the efficiency of PEMFC depends on heat loss in-between critical range. In this study, a numerical approach is used to investigate heat transfer performance of a (PEMFC) cooling channel. The heat transfer rate, convective heat transfer coefficient, temperature distribution and pressure drop were evaluated in this work. All these results were carried out on, 0.2, 0.4, 0.6 0.8 and 1 kg/s of mass flow rate of coolant in the PEMFC cooling channel. Ansys Fluent is used for the numerical investigation. The diamond shape extended staggered pattern cooling channel were used in fuel cell for distributed flow. In this study, 2mm transverse pitch whereas 1mm, 1.5 mm and 2 mm longitudinal pitch with diamond shape extended in PEMFC cooling channel are used. However, design of experiments method was used to sort optimum results. The results reveal the extended staggered cooling channel improve heat transfer performance, 2mm and 1.5 mm transverse and longitudinal pitch respectively gave better heat transfer results and slightly higher pressure drops than 2mm pitch. Turbulence kinetic increases with decreasing transverse pitch and flow distribution improved with longitudinal pitch.
{"title":"Heat Transfer Performance Evaluation of PEMFC With Diamond-Shaped Staggered Cooling Channel","authors":"Pirbux Mughal, Yadong He, Ramzan Luhur","doi":"10.1115/imece2022-95589","DOIUrl":"https://doi.org/10.1115/imece2022-95589","url":null,"abstract":"\u0000 The fossil fuel depletion and environmental pollution are global challenges. Hydrogen is one of the most abundant elements on earth. Recently, scientists and researchers are investigating water splitting to produce oxy-hydrogen for internal combustion engines. Several studies have been published where hydrogen was used to generate electricity. The proton exchange membrane fuel cell (PEMFC) is an alternative energy resource for future electric vehicles. The reaction of PEMFC includes hydrogen molecules splitting as hydrogen ions and electrons on the anode whereas proton meet with oxygen and electrons and form water and release heat on the cathode. There are several processes involved in heat generation in PEMFC such as resistance in current flow, entropic heat reaction, and irreversibility of the electrochemical reactions. The generated heat in PEMFC is removed through cooling channels. The heat transfer rate depends on thermal properties. The design of the such as polymer electrolyte membrane, catalyst layer, gas diffusion layer, and electrodes have different thermal properties which influence heat transfer. Proper thermal management is critical part of PEMFC operation. Because the efficiency of PEMFC depends on heat loss in-between critical range. In this study, a numerical approach is used to investigate heat transfer performance of a (PEMFC) cooling channel. The heat transfer rate, convective heat transfer coefficient, temperature distribution and pressure drop were evaluated in this work. All these results were carried out on, 0.2, 0.4, 0.6 0.8 and 1 kg/s of mass flow rate of coolant in the PEMFC cooling channel. Ansys Fluent is used for the numerical investigation. The diamond shape extended staggered pattern cooling channel were used in fuel cell for distributed flow. In this study, 2mm transverse pitch whereas 1mm, 1.5 mm and 2 mm longitudinal pitch with diamond shape extended in PEMFC cooling channel are used. However, design of experiments method was used to sort optimum results. The results reveal the extended staggered cooling channel improve heat transfer performance, 2mm and 1.5 mm transverse and longitudinal pitch respectively gave better heat transfer results and slightly higher pressure drops than 2mm pitch. Turbulence kinetic increases with decreasing transverse pitch and flow distribution improved with longitudinal pitch.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121256310","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}
Inês Gonçalves, J. Marques, J. Silva, J. Teixeira, F. Alvelos, T. Tavares, S. Teixeira
Wildfires are a worldwide phenomenon that as an impact on all surrounding forms of life. Studying these events is essential to develop and optimize the tools used for combat and prevention, and its behavior is associated with the state of the vegetation, atmospheric conditions, ground properties, and many others, constituting an expensive and challenging task. This work presents itself as a complementary work to study the flow over a forest through a CFD model, which causes a modification in the velocity profile due to the drag produced by the forest presence, and the values obtained can be used in a mathematical model to study the fire rate of spread and fireline intensity considering the new velocity field. The CFD model was applied in the commercial software Ansys Fluent. The results confirmed that the wind is a dominant force during a forest fire, i.e., at high velocities the fire has an aggressive behavior and at low velocities tends to calm down. However, due to the unpredictability of certain weather conditions, it is dangerous to say that a forest fire is fully controlled since its behavior can change in a matter of minutes.
{"title":"Development of CFD Model to Study the Spread of Wildfires","authors":"Inês Gonçalves, J. Marques, J. Silva, J. Teixeira, F. Alvelos, T. Tavares, S. Teixeira","doi":"10.1115/imece2022-95980","DOIUrl":"https://doi.org/10.1115/imece2022-95980","url":null,"abstract":"\u0000 Wildfires are a worldwide phenomenon that as an impact on all surrounding forms of life. Studying these events is essential to develop and optimize the tools used for combat and prevention, and its behavior is associated with the state of the vegetation, atmospheric conditions, ground properties, and many others, constituting an expensive and challenging task.\u0000 This work presents itself as a complementary work to study the flow over a forest through a CFD model, which causes a modification in the velocity profile due to the drag produced by the forest presence, and the values obtained can be used in a mathematical model to study the fire rate of spread and fireline intensity considering the new velocity field. The CFD model was applied in the commercial software Ansys Fluent.\u0000 The results confirmed that the wind is a dominant force during a forest fire, i.e., at high velocities the fire has an aggressive behavior and at low velocities tends to calm down. However, due to the unpredictability of certain weather conditions, it is dangerous to say that a forest fire is fully controlled since its behavior can change in a matter of minutes.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"180 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124492880","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}
A relatively low specific speed dry pit solids handling pump was designed from scratch with pure 3D CFD virtual testing. In-house codes were used to provide preliminary design of the impeller, volute, etc. The 3D CFD tool Simerics-MP+ was employed for improvement of the design to achieve the desired pump performance. The virtual tests covered a wide range of flowrates from 40% to 130% of the best efficiency point (BEP). Final physical testing shows the CFD predictions are in good agreement with the measurements.
{"title":"Design a Low Specific Speed Dry Pit Solids Handling Pump With Pure 3-D Computational Fluid Dynamics Virtual Testing","authors":"Azfar Ali, Zhuoyu Zhou","doi":"10.1115/imece2022-94551","DOIUrl":"https://doi.org/10.1115/imece2022-94551","url":null,"abstract":"\u0000 A relatively low specific speed dry pit solids handling pump was designed from scratch with pure 3D CFD virtual testing. In-house codes were used to provide preliminary design of the impeller, volute, etc. The 3D CFD tool Simerics-MP+ was employed for improvement of the design to achieve the desired pump performance. The virtual tests covered a wide range of flowrates from 40% to 130% of the best efficiency point (BEP). Final physical testing shows the CFD predictions are in good agreement with the measurements.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124962871","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}
Commercial thermal desalination plants usually leverage static flash evaporation and vapor separation processes that occur separately in large chambers. Depending on the level of purity — the product can be used for potable water (for human consumption), for agriculture or ranching, or as input for industrial processes (such as in injection wells in oil and gas production operations). Currently, static methods such as Multi Stage Flash (MSF) or Multi Effect Distillation (MED) are widely used (in addition to Reverse Osmosis) for desalination. These static methods occupy large land area (large footprint). This in turn drives up the capital and production costs of the resulting purified water obtained in these techniques. Desalination processes that leverage evaporation and vapor separation in the same chamber (dynamically) have smaller form factors which confers lower cost of desalination. Thus, the motivation of our study is to develop a novel apparatus to simultaneously generate vapor by flash evaporation and separate the produced vapor in the same apparatus. The novel apparatus is geared for desalination of sea water, remediation of produced water from process-industries and other sources of saline water (such as brackish water) that are deemed unfit for human consumption. The end goal of the project is to develop a solar-thermal desalination platform by leveraging hot saline water as input from solar ponds. In this experimental study, the thermal-hydraulic performance of a prototype (lab-scale) dynamic vapor generation and swirl flow phase separation apparatus is explored for determining the efficacy of this novel concept. Heated water from a constant temperature supply tank (that is comparable to a solar pond in real life) is passed through injection passages into the flow-separation apparatus. As the water flows through the injection passages, vapor bubbles are generated inside the flow passages due to local superheating of the liquid caused by frictional pressure drop. Conversion of liquid into vapor continues as the liquid-vapor mixture flows through the injector ports and eventually the mixture enters a larger separation tube tangentially. Due to the tangential injection of the two-phase mixture, a centrifugal force acts to separate the water and vapor inside the separation tube. The liquid is pushed to the periphery (i.e., the walls) of the separation tube while the vapor forms a stable core at the center. A vapor retrieval tube is then positioned at the center of the vapor core to extract vapor which is then condensed inside the condenser. The formation of the vapor core is demonstrated for different operating conditions (supply liquid flow rates) and maximum superheat (temperature difference between supply tank and condenser) ranging between 45–52°C. Based on this study, the optimal operating conditions for maximizing the thermal conversion upstream of the test section are presented.
{"title":"Experimental Investigation of Solar-Thermal Desalination Platform Leveraging Dynamic Flash Evaporation and Swirl Flow Separator","authors":"A. Thyagarajan, V. Dhir, D. Banerjee","doi":"10.1115/imece2022-96099","DOIUrl":"https://doi.org/10.1115/imece2022-96099","url":null,"abstract":"\u0000 Commercial thermal desalination plants usually leverage static flash evaporation and vapor separation processes that occur separately in large chambers. Depending on the level of purity — the product can be used for potable water (for human consumption), for agriculture or ranching, or as input for industrial processes (such as in injection wells in oil and gas production operations). Currently, static methods such as Multi Stage Flash (MSF) or Multi Effect Distillation (MED) are widely used (in addition to Reverse Osmosis) for desalination. These static methods occupy large land area (large footprint). This in turn drives up the capital and production costs of the resulting purified water obtained in these techniques.\u0000 Desalination processes that leverage evaporation and vapor separation in the same chamber (dynamically) have smaller form factors which confers lower cost of desalination. Thus, the motivation of our study is to develop a novel apparatus to simultaneously generate vapor by flash evaporation and separate the produced vapor in the same apparatus. The novel apparatus is geared for desalination of sea water, remediation of produced water from process-industries and other sources of saline water (such as brackish water) that are deemed unfit for human consumption. The end goal of the project is to develop a solar-thermal desalination platform by leveraging hot saline water as input from solar ponds.\u0000 In this experimental study, the thermal-hydraulic performance of a prototype (lab-scale) dynamic vapor generation and swirl flow phase separation apparatus is explored for determining the efficacy of this novel concept. Heated water from a constant temperature supply tank (that is comparable to a solar pond in real life) is passed through injection passages into the flow-separation apparatus. As the water flows through the injection passages, vapor bubbles are generated inside the flow passages due to local superheating of the liquid caused by frictional pressure drop. Conversion of liquid into vapor continues as the liquid-vapor mixture flows through the injector ports and eventually the mixture enters a larger separation tube tangentially. Due to the tangential injection of the two-phase mixture, a centrifugal force acts to separate the water and vapor inside the separation tube. The liquid is pushed to the periphery (i.e., the walls) of the separation tube while the vapor forms a stable core at the center. A vapor retrieval tube is then positioned at the center of the vapor core to extract vapor which is then condensed inside the condenser.\u0000 The formation of the vapor core is demonstrated for different operating conditions (supply liquid flow rates) and maximum superheat (temperature difference between supply tank and condenser) ranging between 45–52°C. Based on this study, the optimal operating conditions for maximizing the thermal conversion upstream of the test section are presented.","PeriodicalId":292222,"journal":{"name":"Volume 8: Fluids Engineering; Heat Transfer and Thermal Engineering","volume":"181 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122080623","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}
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