Mateo Elias Sanchez Cabarcas, Jose Alejandro Bedoya Villegas, Alvaro de Jesus Sierra Aragon, Imanol Rodriguez Roldan, Daniel Alejandro Alvarez Silva, Jaime Mesa, Antonio J. Bula, Arturo Gonzalez-Quiroga
Abstract Gas turbine power plants play a crucial role in meeting the growing demand for electrical energy. However, their performance can be hindered by high ambient temperatures and humidity levels in tropical climates, leading to a drop in power output. This study investigates the potential benefits of using inlet air cooling with desiccant dehumidification and evaporative cooling to improve the performance of gas turbine power plants in tropical regions. The results show that this inlet air cooling method, integrating evaporative cooling, desiccant wheel, and Maisotsenko cooler, is a viable alternative for mitigating the performance decrease of gas turbines in hot tropical conditions. Furthermore, the compressor inlet temperature can be reduced on average by 11.5 °C by using turbine exhaust gases to heat the regeneration air utilized in the desiccant wheel for dehumidification. Additionally, the power requirement of the inlet air cooling system amounts to around 0.9 MW compared with an improvement of more than 2 MW in power output at peak temperature. Further research is needed to understand and quantify other benefits related to inlet air cooling, such as reducing emissions of harmful pollutants and operating at higher turbine inlet temperatures.
{"title":"Enhancing Gas Turbine Power Plant Performance in Tropical Climates by Using Inlet Air Cooling with Desiccant Dehumidification and Evaporative Cooling","authors":"Mateo Elias Sanchez Cabarcas, Jose Alejandro Bedoya Villegas, Alvaro de Jesus Sierra Aragon, Imanol Rodriguez Roldan, Daniel Alejandro Alvarez Silva, Jaime Mesa, Antonio J. Bula, Arturo Gonzalez-Quiroga","doi":"10.1115/1.4063679","DOIUrl":"https://doi.org/10.1115/1.4063679","url":null,"abstract":"Abstract Gas turbine power plants play a crucial role in meeting the growing demand for electrical energy. However, their performance can be hindered by high ambient temperatures and humidity levels in tropical climates, leading to a drop in power output. This study investigates the potential benefits of using inlet air cooling with desiccant dehumidification and evaporative cooling to improve the performance of gas turbine power plants in tropical regions. The results show that this inlet air cooling method, integrating evaporative cooling, desiccant wheel, and Maisotsenko cooler, is a viable alternative for mitigating the performance decrease of gas turbines in hot tropical conditions. Furthermore, the compressor inlet temperature can be reduced on average by 11.5 °C by using turbine exhaust gases to heat the regeneration air utilized in the desiccant wheel for dehumidification. Additionally, the power requirement of the inlet air cooling system amounts to around 0.9 MW compared with an improvement of more than 2 MW in power output at peak temperature. Further research is needed to understand and quantify other benefits related to inlet air cooling, such as reducing emissions of harmful pollutants and operating at higher turbine inlet temperatures.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134975897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Active materials, such as the proposed variable thermal conductivity metamaterial, enables new thermal designs and low-cost, low-power, passive thermal control. Thermal control of satellites conventionally requires active thermal control systems that are expensive, large, inefficient, energy-intensive, and unavailable for CubeSats. For CubeSats, the thermal system's primary design consideration is the high-temperature operation case. The thermal path is designed to reject as much heat as possible to prevent overheating. In other cases, such as during a power anomaly, the oversized thermal path results in rapid cooling, culminating in mission failure due to thermal limits on the electronics or batteries. Improving the thermal control of CubeSats can enable new thermally challenging missions, increase satellite longevity, and increase mission success rate by controlling and dynamic thermal environment. The materials available for thermal management are limited, but new engineered materials provide unique opportunities to change how satellites adapt to dynamic environmental and thermal loads. This paper investigates using an adaptive metamaterial designed to passively change its thermal conductivity as a function of temperature to meet the needs of the satellite. The thermal performance of a CubeSat is evaluated with a variable thermal conductivity metamaterial located in the critical thermal path from the satellite to the radiator. The system's performance using two metamaterial configurations is compared to a baseline copper thermal path. Multiple satellite thermal operation cases are investigated to determine the operation ranges, and the metamaterial's performance in various conditions is quantified.
{"title":"Variable Thermal Conductivity Metamaterials Applied to Passive Thermal Control of Satellites","authors":"Austin Phoenix","doi":"10.1115/1.4063365","DOIUrl":"https://doi.org/10.1115/1.4063365","url":null,"abstract":"\u0000 Active materials, such as the proposed variable thermal conductivity metamaterial, enables new thermal designs and low-cost, low-power, passive thermal control. Thermal control of satellites conventionally requires active thermal control systems that are expensive, large, inefficient, energy-intensive, and unavailable for CubeSats. For CubeSats, the thermal system's primary design consideration is the high-temperature operation case. The thermal path is designed to reject as much heat as possible to prevent overheating. In other cases, such as during a power anomaly, the oversized thermal path results in rapid cooling, culminating in mission failure due to thermal limits on the electronics or batteries. Improving the thermal control of CubeSats can enable new thermally challenging missions, increase satellite longevity, and increase mission success rate by controlling and dynamic thermal environment. The materials available for thermal management are limited, but new engineered materials provide unique opportunities to change how satellites adapt to dynamic environmental and thermal loads. This paper investigates using an adaptive metamaterial designed to passively change its thermal conductivity as a function of temperature to meet the needs of the satellite. The thermal performance of a CubeSat is evaluated with a variable thermal conductivity metamaterial located in the critical thermal path from the satellite to the radiator. The system's performance using two metamaterial configurations is compared to a baseline copper thermal path. Multiple satellite thermal operation cases are investigated to determine the operation ranges, and the metamaterial's performance in various conditions is quantified.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"12 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87254079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhansheng Chen, Pinghui Zhao, Teng Wan, Yixuan Jin, Xiaohu Wang, M. Lei, Yuanjie Li, C. Peng
In the fusion power conversion system, printed circuit heat exchanger (PCHE) between molten salt (MS) and supercritical carbon dioxide (sCO2) transfers huge heat between loops. To improve heat transfer efficiency, a new heterogeneous PCHE with MS zigzag passage and sCO2 airfoil fin passage was proposed. A one-dimensional simulation of the new PCHE was conducted to study the effects of the plate number and the length on its pressure drop, MS mass flow rate, capital cost and operating cost. Then, a new single objective optimization of the total cost was performed by the genetic algorithm based on the CFETR parameters. Finally, the new optimal PCHE was compared with the PCHE with MS straight passage and sCO2 airfoil fin passage. The results show that the length and the plate number of the PCHE have an important effect on the pressure drop and its cost. The optimal geometry scheme with the minimum cost is given for the application to CFETR. By comparison with the MS straight passage PCHE, it is found that the total cost of the new PCHE is reduced by 5.7% and the volume of the heat exchanger is reduced by 10.7%.
{"title":"Design and optimization of a new heterogeneous printed circuit plate heat exchanger with molten salt zigzag passage and supercritical CO2 airfoil fin passage","authors":"Zhansheng Chen, Pinghui Zhao, Teng Wan, Yixuan Jin, Xiaohu Wang, M. Lei, Yuanjie Li, C. Peng","doi":"10.1115/1.4063294","DOIUrl":"https://doi.org/10.1115/1.4063294","url":null,"abstract":"\u0000 In the fusion power conversion system, printed circuit heat exchanger (PCHE) between molten salt (MS) and supercritical carbon dioxide (sCO2) transfers huge heat between loops. To improve heat transfer efficiency, a new heterogeneous PCHE with MS zigzag passage and sCO2 airfoil fin passage was proposed. A one-dimensional simulation of the new PCHE was conducted to study the effects of the plate number and the length on its pressure drop, MS mass flow rate, capital cost and operating cost. Then, a new single objective optimization of the total cost was performed by the genetic algorithm based on the CFETR parameters. Finally, the new optimal PCHE was compared with the PCHE with MS straight passage and sCO2 airfoil fin passage. The results show that the length and the plate number of the PCHE have an important effect on the pressure drop and its cost. The optimal geometry scheme with the minimum cost is given for the application to CFETR. By comparison with the MS straight passage PCHE, it is found that the total cost of the new PCHE is reduced by 5.7% and the volume of the heat exchanger is reduced by 10.7%.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"1 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89544517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jaouad Ennissioui, El Mahjoub Benghoulam, T. El Rhafiki, S. Fertahi
Solar dryers are traditional devices used for drying various products. Different indirect solar dryer (ISD) geometries were theoretically examined using computational fluid dynamics (CFD). The paper presents a numerical investigation of two indirect solar dryers using CFD simulation, comparing the velocity and thermal performance of dryers with smooth and corrugated absorber plates. The temperature values obtained by numerical simulations were compared to the experimental measurements and it was found a maximum variation difference of 1.26%. The maximum velocity in the SAC and the value of average temperature at the SAC outlet were found to be 0.58 m/s and 336 K for the smooth absorber ISD, and 0.77 m/s and 350 K for the corrugated absorber ISD. It was observed that the corrugated absorber plate exhibited superior thermal performance and a higher maximum velocity compared to the smooth absorber plate. Within the cabinet, a uniform temperature profile was observed, particularly for the corrugated case. V-shaped absorber plate offer higher heat transfer rates, increased turbulence, and greater surface area for heat transfer, making them more efficient for drying processes compared to smooth absorber plate. Therefore, corrugated absorber plates in solar air collectors is a more efficient option than using smooth absorber plates.
{"title":"3D CFD modeling using the RANS approach of Indirect-Type Solar Dryers based on Smooth and Corrugated Absorber Plates","authors":"Jaouad Ennissioui, El Mahjoub Benghoulam, T. El Rhafiki, S. Fertahi","doi":"10.1115/1.4063295","DOIUrl":"https://doi.org/10.1115/1.4063295","url":null,"abstract":"\u0000 Solar dryers are traditional devices used for drying various products. Different indirect solar dryer (ISD) geometries were theoretically examined using computational fluid dynamics (CFD). The paper presents a numerical investigation of two indirect solar dryers using CFD simulation, comparing the velocity and thermal performance of dryers with smooth and corrugated absorber plates. The temperature values obtained by numerical simulations were compared to the experimental measurements and it was found a maximum variation difference of 1.26%. The maximum velocity in the SAC and the value of average temperature at the SAC outlet were found to be 0.58 m/s and 336 K for the smooth absorber ISD, and 0.77 m/s and 350 K for the corrugated absorber ISD. It was observed that the corrugated absorber plate exhibited superior thermal performance and a higher maximum velocity compared to the smooth absorber plate. Within the cabinet, a uniform temperature profile was observed, particularly for the corrugated case. V-shaped absorber plate offer higher heat transfer rates, increased turbulence, and greater surface area for heat transfer, making them more efficient for drying processes compared to smooth absorber plate. Therefore, corrugated absorber plates in solar air collectors is a more efficient option than using smooth absorber plates.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"20 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84537832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wei Li, Yongsheng Li, Congbo Li, Ningbo Wang, Jiadong Fu
As the core component of electric vehicles (EVs), the performance of motors affects the use of EVs. Motors are sensitive to temperature, and overheated operating temperature may cause the deterioration of the magnetic properties and the reduction of efficiency. To effectively improve the heat dissipation of the motor, this work presents an incremental learning strategy assisted multi-objective optimization method for an oil-water mixed cooling induction motor (IM). The key parameters of the motor are modeled parametrically, and design of experiment is carried out by Latin hypercube method. The incremental learning strategy is used to improve the low accuracy of surrogate model. Four multi-objective optimization algorithms are used to drive the optimization process, and the optimal cooling system parameters are obtained. The reliability of the proposed method is verified by motor bench experiments. The optimization results suggest that the maximum temperature of the motor is reduced by 5 K after optimization, and the heat dissipation of the motor is improved effectively, which provides a theoretical basis for further promotion and improvement of induction motor.
{"title":"Incremental Learning Strategy Assisted Multi-Objective Optimization for An Oil-Water Mixed Cooling Motor","authors":"Wei Li, Yongsheng Li, Congbo Li, Ningbo Wang, Jiadong Fu","doi":"10.1115/1.4063245","DOIUrl":"https://doi.org/10.1115/1.4063245","url":null,"abstract":"\u0000 As the core component of electric vehicles (EVs), the performance of motors affects the use of EVs. Motors are sensitive to temperature, and overheated operating temperature may cause the deterioration of the magnetic properties and the reduction of efficiency. To effectively improve the heat dissipation of the motor, this work presents an incremental learning strategy assisted multi-objective optimization method for an oil-water mixed cooling induction motor (IM). The key parameters of the motor are modeled parametrically, and design of experiment is carried out by Latin hypercube method. The incremental learning strategy is used to improve the low accuracy of surrogate model. Four multi-objective optimization algorithms are used to drive the optimization process, and the optimal cooling system parameters are obtained. The reliability of the proposed method is verified by motor bench experiments. The optimization results suggest that the maximum temperature of the motor is reduced by 5 K after optimization, and the heat dissipation of the motor is improved effectively, which provides a theoretical basis for further promotion and improvement of induction motor.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"47 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77227757","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The microchannel cooling plate is a vital component in an efficient battery thermal management system (BTMS) that has been widely used to design battery modules for electric vehicles. In this study, regarding the leaf vein structure of plantain, a novel bionic cooling plate similar to the plantain leaf vein channels was proposed. A three-dimensional mathematical model of BTMS including the bionic cooling plate was established. The effects of the structure type, reducing angle of main inlet channel, the number, angle, and width of branch channels, and inlet mass flow rate of the coolant on the thermal performance of the BTMS were investigated. The results indicated that the cooling plate of single inlet and double outlet channel with leaf veins exhibited excellent comprehensive performance. The increase of the reducing angle of the main inlet channel decreased the pressure drop by up to 43.55% but could not improve the temperature uniformity of batteries, the maximum temperature difference of batteries increased by 0.11 °C. A larger number of branch channels and a smaller angle of branch channels can improve the cooling performance of BTMS, while the increase in the width of branch channels significantly decreased the pressure drop. At a coolant inlet mass flow rate of 1 g/s, the BTMS can control the maximum temperature and maximum temperature difference of the batteries at a 3C discharge rate to 31.75 °C and 4.95 °C, respectively, and exhibited excellent temperature uniformity at low pressure drop (669 Pa).
{"title":"Performance study of battery thermal management system with a bionic cooling plate based on leaf vein channels of plantain","authors":"Zhiguo Tang, Ran Sun, Kuan Lu, Jianping Cheng","doi":"10.1115/1.4063244","DOIUrl":"https://doi.org/10.1115/1.4063244","url":null,"abstract":"\u0000 The microchannel cooling plate is a vital component in an efficient battery thermal management system (BTMS) that has been widely used to design battery modules for electric vehicles. In this study, regarding the leaf vein structure of plantain, a novel bionic cooling plate similar to the plantain leaf vein channels was proposed. A three-dimensional mathematical model of BTMS including the bionic cooling plate was established. The effects of the structure type, reducing angle of main inlet channel, the number, angle, and width of branch channels, and inlet mass flow rate of the coolant on the thermal performance of the BTMS were investigated. The results indicated that the cooling plate of single inlet and double outlet channel with leaf veins exhibited excellent comprehensive performance. The increase of the reducing angle of the main inlet channel decreased the pressure drop by up to 43.55% but could not improve the temperature uniformity of batteries, the maximum temperature difference of batteries increased by 0.11 °C. A larger number of branch channels and a smaller angle of branch channels can improve the cooling performance of BTMS, while the increase in the width of branch channels significantly decreased the pressure drop. At a coolant inlet mass flow rate of 1 g/s, the BTMS can control the maximum temperature and maximum temperature difference of the batteries at a 3C discharge rate to 31.75 °C and 4.95 °C, respectively, and exhibited excellent temperature uniformity at low pressure drop (669 Pa).","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"32 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81930188","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In order to reveal the gas-liquid distribution, heat and mass transfer characteristics inside a gravity heat pipe, the bubble behavior and the flow regime transition during the phase-change process were examined by employing a copper-water heat pipe, with the length of 500 mm and Φ22 × 1.5 mm. The results indicate that in the process of phase change, the typical flow regimes of bubble flow, slug flow and churn flow can be observed in the evaporator, and the presence of bubbles has an obvious disturbance on the flow field. In addition, the discontinuous liquid film plays an important role in the heat transfer mechanism in the condenser, which allows the vapor to contact the wall directly and reduces the heat transfer resistance. The temperature difference between the evaporator and the condenser can be reduced by adjusting the saturation temperature, so as to effectively improve the heat transfer performance of the heat pipe and contribute to the practical engineering design.
{"title":"Numerical investigation into the gas-liquid two-phase flow regime and heat transfer characteristics in a gravity heat pipe","authors":"Peng Lu, Xiaodie Yan, Qinshan Yang, Jianghong Wei","doi":"10.1115/1.4063243","DOIUrl":"https://doi.org/10.1115/1.4063243","url":null,"abstract":"\u0000 In order to reveal the gas-liquid distribution, heat and mass transfer characteristics inside a gravity heat pipe, the bubble behavior and the flow regime transition during the phase-change process were examined by employing a copper-water heat pipe, with the length of 500 mm and Φ22 × 1.5 mm. The results indicate that in the process of phase change, the typical flow regimes of bubble flow, slug flow and churn flow can be observed in the evaporator, and the presence of bubbles has an obvious disturbance on the flow field. In addition, the discontinuous liquid film plays an important role in the heat transfer mechanism in the condenser, which allows the vapor to contact the wall directly and reduces the heat transfer resistance. The temperature difference between the evaporator and the condenser can be reduced by adjusting the saturation temperature, so as to effectively improve the heat transfer performance of the heat pipe and contribute to the practical engineering design.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"5 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89031718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I-Cheng Huang, Kuan-Hsueh Lin, Chih-Yung Huang, Yao-Hsien Liu
Abstract Effusion film cooling is effective for cooling high-temperature turbine blades because it requires less coolant and produces a more uniform temperature distribution than conventional film cooling. Effusion cooling for a cylindrical model representing the leading edge of a gas turbine blade was investigated. The experiment was performed in a low-speed wind tunnel at a Reynolds number of 100,000. Pressure-sensitive paint was used to measure the adiabatic film cooling effectiveness. Additive manufacturing was used to fabricate a porous structure on the test cylinder for effusion cooling. Both simple and compound angles were used for cooling injection. The effects of streamwise and spanwise hole spacings, turbulence intensities (1% and 8.7%), and blowing ratios (0.075, 0.15, 0.3, and 0.6) were studied at a fixed density ratio of 1. The effusion hole diameter was 0.1 cm, and the spanwise hole pitch-to-diameter ratio was either 2 or 4. Compared with conventional film cooing, effusion cooling achieved a higher cooling effectiveness and produced a better coolant coverage. Increasing the streamwise spacing noticeably reduced the cooling effectiveness for the simple-angle design due to film lift-off; the compound-angle designs thus achieved higher effectiveness. The simple-angle holes were more sensitive to changes in the mainstream turbulence intensity; increases in the turbulence intensity promoted the mixing of the coolant with the mainstream. Moreover, effusion cooling was more resistant to coolant lift-off at high blowing ratios.
{"title":"Experimental Investigation of Effusion Film Cooling on a Cylindrical Leading Edge Model","authors":"I-Cheng Huang, Kuan-Hsueh Lin, Chih-Yung Huang, Yao-Hsien Liu","doi":"10.1115/1.4062955","DOIUrl":"https://doi.org/10.1115/1.4062955","url":null,"abstract":"Abstract Effusion film cooling is effective for cooling high-temperature turbine blades because it requires less coolant and produces a more uniform temperature distribution than conventional film cooling. Effusion cooling for a cylindrical model representing the leading edge of a gas turbine blade was investigated. The experiment was performed in a low-speed wind tunnel at a Reynolds number of 100,000. Pressure-sensitive paint was used to measure the adiabatic film cooling effectiveness. Additive manufacturing was used to fabricate a porous structure on the test cylinder for effusion cooling. Both simple and compound angles were used for cooling injection. The effects of streamwise and spanwise hole spacings, turbulence intensities (1% and 8.7%), and blowing ratios (0.075, 0.15, 0.3, and 0.6) were studied at a fixed density ratio of 1. The effusion hole diameter was 0.1 cm, and the spanwise hole pitch-to-diameter ratio was either 2 or 4. Compared with conventional film cooing, effusion cooling achieved a higher cooling effectiveness and produced a better coolant coverage. Increasing the streamwise spacing noticeably reduced the cooling effectiveness for the simple-angle design due to film lift-off; the compound-angle designs thus achieved higher effectiveness. The simple-angle holes were more sensitive to changes in the mainstream turbulence intensity; increases in the turbulence intensity promoted the mixing of the coolant with the mainstream. Moreover, effusion cooling was more resistant to coolant lift-off at high blowing ratios.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136337534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The hybrid heat exchangers (H2Xs) can be used for heat exchange equipment between high-temperature exhaust gas from ships and high-pressure supercritical carbon dioxide (S-CO2) from S-CO2 power cycle. We investigate structural stress characteristics of the H2Xs based on thermal-hydraulic performance. Air and S-CO2 are employed as the working fluids and the Stainless Steel 316 (SS316) as the solid substrate. The thermal-hydraulic performance and structural stress characteristics of the H2Xs is conducted by Fluent and Mechanical, respectively. The results shows the mechanical stress induced by pressure loading and the thermal stress induced by temperature gradient are found to be equally important sources of stress. At the inlet and outlet of the H2Xs, the total stress along all paths is not smooth and continuous, and there will be a significant change due to the change in temperature gradient. The mechanical stress caused by the fluid pressure loss is almost negligible. The change of inlet mass flow rate and temperature mainly affects the stress distribution of the left and right walls on the fin channel. The pressure variation of the diesel engine has little effect on the total stress. Importantly, the total stress intensity of the H2X is mainly affected by the change of S-CO2 fluid pressure.
{"title":"Structural stress intensity analysis of hybrid heat exchangers based on thermal hydraulic performance in S-CO2 power cycle","authors":"Jiawei Wang, Y.W. Sun, Mingjian Lu, Xinping Yan","doi":"10.1115/1.4063189","DOIUrl":"https://doi.org/10.1115/1.4063189","url":null,"abstract":"The hybrid heat exchangers (H2Xs) can be used for heat exchange equipment between high-temperature exhaust gas from ships and high-pressure supercritical carbon dioxide (S-CO2) from S-CO2 power cycle. We investigate structural stress characteristics of the H2Xs based on thermal-hydraulic performance. Air and S-CO2 are employed as the working fluids and the Stainless Steel 316 (SS316) as the solid substrate. The thermal-hydraulic performance and structural stress characteristics of the H2Xs is conducted by Fluent and Mechanical, respectively. The results shows the mechanical stress induced by pressure loading and the thermal stress induced by temperature gradient are found to be equally important sources of stress. At the inlet and outlet of the H2Xs, the total stress along all paths is not smooth and continuous, and there will be a significant change due to the change in temperature gradient. The mechanical stress caused by the fluid pressure loss is almost negligible. The change of inlet mass flow rate and temperature mainly affects the stress distribution of the left and right walls on the fin channel. The pressure variation of the diesel engine has little effect on the total stress. Importantly, the total stress intensity of the H2X is mainly affected by the change of S-CO2 fluid pressure.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"23 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87603782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The thermal performance of earth air tunnel heat exchanger (EATHE) integrated single span saw-tooth greenhouse was assessed in peak summer for tropical climate. With side and roof vent opened, natural ventilation due to wind and stack effect controlled the air movement and temperature inside the GH. In this configuration average temperature inside GH remained higher than the ambient temperature by 1.5 °C for the entire period of the experiment. For EATHE (installed at a depth of 3.2 m) assisted GH with polyethylene (PE) cover, the air from EATHE outlet entered inside GH at 33 °C and the average temperature within the GH was maintained at 4 °C lower than the ambient temperature. When the shading net was installed over the PE cover with EATHE, the transmitted radiations into the GH were reduced from the roof and the inside temperature was maintained 7 °C below the average ambient temperature (i.e. 45 °C). The measured temperatures along the length of EATHE were compared with the indigenously developed code-named PEAT (Performance analysis of Earth Air Tunnel) and found to be in good agreement within ± 4.5 % deviation. The temperature distribution inside the GH was predicted using a CFD model in Ansys-FLUENT with ± 5 % deviation from experimental results. With parametric analysis from the PEAT code and CFD model, desired depth of EATHE and mass flow rate of air required to bring down the GH indoor temperatures to the optimum plant growth range was determined.
{"title":"An Investigation of the Thermal Performance of a Tropical Greenhouse Constructed with an Earth Air Heat Exchanger","authors":"Samar Singhal, A. K. Yadav, Ravi Prakash","doi":"10.1115/1.4063164","DOIUrl":"https://doi.org/10.1115/1.4063164","url":null,"abstract":"\u0000 The thermal performance of earth air tunnel heat exchanger (EATHE) integrated single span saw-tooth greenhouse was assessed in peak summer for tropical climate. With side and roof vent opened, natural ventilation due to wind and stack effect controlled the air movement and temperature inside the GH. In this configuration average temperature inside GH remained higher than the ambient temperature by 1.5 °C for the entire period of the experiment. For EATHE (installed at a depth of 3.2 m) assisted GH with polyethylene (PE) cover, the air from EATHE outlet entered inside GH at 33 °C and the average temperature within the GH was maintained at 4 °C lower than the ambient temperature. When the shading net was installed over the PE cover with EATHE, the transmitted radiations into the GH were reduced from the roof and the inside temperature was maintained 7 °C below the average ambient temperature (i.e. 45 °C). The measured temperatures along the length of EATHE were compared with the indigenously developed code-named PEAT (Performance analysis of Earth Air Tunnel) and found to be in good agreement within ± 4.5 % deviation. The temperature distribution inside the GH was predicted using a CFD model in Ansys-FLUENT with ± 5 % deviation from experimental results. With parametric analysis from the PEAT code and CFD model, desired depth of EATHE and mass flow rate of air required to bring down the GH indoor temperatures to the optimum plant growth range was determined.","PeriodicalId":17404,"journal":{"name":"Journal of Thermal Science and Engineering Applications","volume":"17 1","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86497326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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