Pub Date : 2024-11-18DOI: 10.1016/j.ijthermalsci.2024.109552
Dingbiao Wang , Hongyang Song , Guanghui Wang , Yushen Yang , Shuai Wang , Sa Xiang
Different forms of inlet and outlet arrangements in microchannel heat sinks have a significant impact on efficient heat dissipation. In this paper, under the framework of the finite element method coupled with the Method of Moving Asymptotes (MMA), three novel topology structures are proposed. Using Solid Isotropic Material with Penalization Parametrization (SIMP), the topology results with different inlet and outlet arrangements are compared and analyzed, with minimizing the average solid temperature, maximizing the heat transfer capacity and minimizing the power consumption per unit of heat transfer, and 207 sets of results are obtained. The optimized results were analyzed by the Nusselt number (Nu), the friction factor (f) and the Performance Evaluation Criterion (PEC). The results present that the heat transfer performance of the optimized three arrangements in the 207 arrangements are enhanced by 133.6 %, 112.56 % and 135.79 %, respectively, and the PECs improve up to 73.55 %, 65.54 % and 79.78 %, respectively, compared with the horizontal rib inlet and outlet liquid-cooled plate type microchannel heat sink. The results of the present work provide a reference for the optimal design of electronic heat sinks under different working conditions.
{"title":"Optimal arrangements of inlet and outlet in topology liquid-cooled microchannel heat sink based on Multi-Objective optimization","authors":"Dingbiao Wang , Hongyang Song , Guanghui Wang , Yushen Yang , Shuai Wang , Sa Xiang","doi":"10.1016/j.ijthermalsci.2024.109552","DOIUrl":"10.1016/j.ijthermalsci.2024.109552","url":null,"abstract":"<div><div>Different forms of inlet and outlet arrangements in microchannel heat sinks have a significant impact on efficient heat dissipation. In this paper, under the framework of the finite element method coupled with the Method of Moving Asymptotes (MMA), three novel topology structures are proposed. Using Solid Isotropic Material with Penalization Parametrization (SIMP), the topology results with different inlet and outlet arrangements are compared and analyzed, with minimizing the average solid temperature, maximizing the heat transfer capacity and minimizing the power consumption per unit of heat transfer, and 207 sets of results are obtained. The optimized results were analyzed by the Nusselt number (<em>Nu</em>), the friction factor (<em>f</em>) and the Performance Evaluation Criterion (<em>PEC</em>). The results present that the heat transfer performance of the optimized three arrangements in the 207 arrangements are enhanced by 133.6 %, 112.56 % and 135.79 %, respectively, and the <em>PEC</em>s improve up to 73.55 %, 65.54 % and 79.78 %, respectively, compared with the horizontal rib inlet and outlet liquid-cooled plate type microchannel heat sink. The results of the present work provide a reference for the optimal design of electronic heat sinks under different working conditions.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109552"},"PeriodicalIF":4.9,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents experimental and numerical studies aimed at evaluating and comparing the performances of heat sinks for liquid cooling of a heterogeneous heat-generating surface with multiple heat sources. Various heat sink prototypes were optimized, machined, instrumented, and tested, including a uniform straight channel (RSC) heat sink as the baseline case, an optimized straight channel (OSC) heat sink, and a genetic algorithm-based topology optimization (GATO) heat sink. Infrared (IR) thermography was employed to measure the near-wall fluid temperature field in the heat sink, facilitated by introduction and installation of a sapphire window. The detailed spatial temperature distribution obtained enabled the analysis of heat transfer characteristics at the local level, with the good agreement between CFD results and IR measurement providing a solid validation of the numerical simulation models.
Following this experimental validation, a systematic numerical study was conducted to evaluate the thermal and hydraulic performances of the three heat sinks under a wide range of operating conditions. Results showed that the GATO heat sink consistently outperforms the RSC and OSC heat sinks, exhibiting superior global thermal performances. This was evidenced by its better temperature hotspot removal capability, higher Nu number, higher PEC number, and higher Le Goff number compared to the other heat sinks. The effectiveness and robustness of the GATO approach for heat sink optimization were thereby proven, highlighting its significant potential in addressing general thermal management issues.
本文介绍了实验和数值研究，旨在评估和比较用于多热源异质发热表面液体冷却的散热器的性能。对各种散热器原型进行了优化、加工、仪器检测和测试，包括作为基线的均匀直槽（RSC）散热器、优化直槽（OSC）散热器和基于遗传算法的拓扑优化（GATO）散热器。通过引入和安装蓝宝石窗口，采用红外热成像技术测量散热器的近壁流体温度场。获得的详细空间温度分布有助于分析局部的传热特性，CFD 结果与红外测量结果之间的良好一致性为数值模拟模型提供了可靠的验证。结果表明，GATO 散热器的性能始终优于 RSC 和 OSC 散热器，表现出卓越的整体热性能。与其他散热器相比，GATO 散热器具有更强的温度热点消除能力、更高的 Nu 值、更高的 PEC 值和更高的 Le Goff 值。因此，GATO 方法在散热器优化方面的有效性和稳健性得到了证明，凸显了其在解决一般热管理问题方面的巨大潜力。
{"title":"Numerical and experimental investigation of optimized heat sink designs for liquid cooling of a heterogeneous heating surface with multiple heat sources","authors":"Yijun Li, Stéphane Roux, Cathy Castelain, Gwenaël Biotteau, Lingai Luo, Yilin Fan","doi":"10.1016/j.ijthermalsci.2024.109540","DOIUrl":"10.1016/j.ijthermalsci.2024.109540","url":null,"abstract":"<div><div>This paper presents experimental and numerical studies aimed at evaluating and comparing the performances of heat sinks for liquid cooling of a heterogeneous heat-generating surface with multiple heat sources. Various heat sink prototypes were optimized, machined, instrumented, and tested, including a uniform straight channel (RSC) heat sink as the baseline case, an optimized straight channel (OSC) heat sink, and a genetic algorithm-based topology optimization (GATO) heat sink. Infrared (IR) thermography was employed to measure the near-wall fluid temperature field in the heat sink, facilitated by introduction and installation of a sapphire window. The detailed spatial temperature distribution obtained enabled the analysis of heat transfer characteristics at the local level, with the good agreement between CFD results and IR measurement providing a solid validation of the numerical simulation models.</div><div>Following this experimental validation, a systematic numerical study was conducted to evaluate the thermal and hydraulic performances of the three heat sinks under a wide range of operating conditions. Results showed that the GATO heat sink consistently outperforms the RSC and OSC heat sinks, exhibiting superior global thermal performances. This was evidenced by its better temperature hotspot removal capability, higher <em>Nu</em> number, higher PEC number, and higher Le Goff number compared to the other heat sinks. The effectiveness and robustness of the GATO approach for heat sink optimization were thereby proven, highlighting its significant potential in addressing general thermal management issues.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109540"},"PeriodicalIF":4.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.ijthermalsci.2024.109546
Longjie Li , Qianfan Tang , Xuejin Chen , Can Weng
In this comprehensive study, the applicability and heat transfer dynamics of polymer pin-fin microchannel heat exchangers were investigated through a combination of experimental and numerical approaches. The findings revealed that enhancements in material thermal conductivity do not exhibit a linear correlation with improvements in heat transfer performance. Beyond a certain threshold, the impact of thermal conductivity on temperature stability diminishes significantly. Notably, polymer-based micro heat exchangers demonstrated remarkable temperature uniformity in comparison to other materials. To address the issue of localized thermal peaks in electronic chipsets, a heat exchanger featuring variable pin-fin sizes was designed. This design resulted in a significant reduction in the temperature of the heat source when compared to a constant-size pin-fin configuration. Specifically, variable-size pin-fin structures (the staggered-arrangement variable-size micro-needle-fin heat exchanger (VSPFS) and the inline-arrangement variable-size micro-needle-fin heat exchanger (VIPFS)) achieved temperature reductions in the range of 1.41–3.60K and 6.07–8.48K, respectively, when compared to their isometric counterparts (the staggered-arrangement constant-size micro-needle-fin heat exchanger (ISPFS) and the inline array of constant-size pin-fin microchannel heat exchanger (IIPFS)). Furthermore, these structures significantly decreased the average temperature difference across the heat source, effectively mitigating thermal hotspots by up to 3.23K and 5.73K, respectively. Among the tested configurations, VSPFS exhibited the highest Performance Evaluation Criterion (PEC) value and the smallest increase in entropy generation, highlighting its superior overall thermal management capability. Additionally, as the Reynolds number increased, convective heat transfer entropy generation decreased while fluid friction entropy generation increased, indicating that energy losses due to fluid friction gradually outweighed the benefits of enhanced heat transfer at higher Reynolds numbers.
{"title":"Polymer-based pin-fin microchannel heat exchangers: A comparative study of material and structural effects on performance","authors":"Longjie Li , Qianfan Tang , Xuejin Chen , Can Weng","doi":"10.1016/j.ijthermalsci.2024.109546","DOIUrl":"10.1016/j.ijthermalsci.2024.109546","url":null,"abstract":"<div><div>In this comprehensive study, the applicability and heat transfer dynamics of polymer pin-fin microchannel heat exchangers were investigated through a combination of experimental and numerical approaches. The findings revealed that enhancements in material thermal conductivity do not exhibit a linear correlation with improvements in heat transfer performance. Beyond a certain threshold, the impact of thermal conductivity on temperature stability diminishes significantly. Notably, polymer-based micro heat exchangers demonstrated remarkable temperature uniformity in comparison to other materials. To address the issue of localized thermal peaks in electronic chipsets, a heat exchanger featuring variable pin-fin sizes was designed. This design resulted in a significant reduction in the temperature of the heat source when compared to a constant-size pin-fin configuration. Specifically, variable-size pin-fin structures (the staggered-arrangement variable-size micro-needle-fin heat exchanger (<em>VSPFS</em>) and the inline-arrangement variable-size micro-needle-fin heat exchanger (<em>VIPFS</em>)) achieved temperature reductions in the range of 1.41–3.60<em>K</em> and 6.07–8.48<em>K</em>, respectively, when compared to their isometric counterparts (the staggered-arrangement constant-size micro-needle-fin heat exchanger (<em>ISPFS</em>) and the inline array of constant-size pin-fin microchannel heat exchanger (IIPFS)). Furthermore, these structures significantly decreased the average temperature difference across the heat source, effectively mitigating thermal hotspots by up to 3.23<em>K</em> and 5.73<em>K</em>, respectively. Among the tested configurations, <em>VSPFS</em> exhibited the highest Performance Evaluation Criterion (<em>PEC</em>) value and the smallest increase in entropy generation, highlighting its superior overall thermal management capability. Additionally, as the Reynolds number increased, convective heat transfer entropy generation decreased while fluid friction entropy generation increased, indicating that energy losses due to fluid friction gradually outweighed the benefits of enhanced heat transfer at higher Reynolds numbers.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109546"},"PeriodicalIF":4.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.ijthermalsci.2024.109539
Ye. Pysmennyy, O. Semeniako
Made is the analysis of the particularities of transfer processes with the transversal washing by gas flow of perspective developed heat transfer surfaces – partially finned flat-oval tubes. The analysis is based on complex experimental and numerical studies of the flow structure, static pressure fields, velocities and intensity of their fluctuations, local heat transfer coefficients, performed at Re from 2,5 × 104 to 5 × 104.
It has been demonstrated that due to such tubes’ constructive features a number of small-scale and low-energy-consuming vortex structures are formed at their surface maintaining a relatively high level of flow disturbance in the interfin space. In conjunction with elevated values of local velocities this results in comparable - with regard to the case of completely finned round tubes - level of heat transfer intensity at significantly lower pressure loss.
{"title":"Experimental and numerical investigations of local flow and heat transfer characteristics of partially finned flat-oval tubes","authors":"Ye. Pysmennyy, O. Semeniako","doi":"10.1016/j.ijthermalsci.2024.109539","DOIUrl":"10.1016/j.ijthermalsci.2024.109539","url":null,"abstract":"<div><div>Made is the analysis of the particularities of transfer processes with the transversal washing by gas flow of perspective developed heat transfer surfaces – partially finned flat-oval tubes. The analysis is based on complex experimental and numerical studies of the flow structure, static pressure fields, velocities and intensity of their fluctuations, local heat transfer coefficients, performed at Re from 2,5 × 10<sup>4</sup> to 5 × 10<sup>4</sup>.</div><div>It has been demonstrated that due to such tubes’ constructive features a number of small-scale and low-energy-consuming vortex structures are formed at their surface maintaining a relatively high level of flow disturbance in the interfin space. In conjunction with elevated values of local velocities this results in comparable - with regard to the case of completely finned round tubes - level of heat transfer intensity at significantly lower pressure loss.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109539"},"PeriodicalIF":4.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.ijthermalsci.2024.109551
Yuxuan Li, Chengbao Sun, Zhenkun Cao, Miao Cui, Kun Liu
It is of great importance and challenging to simultaneously determine time-varying aerodynamic heat and temperature-dependent thermo-physical property parameters with high accuracy, for the optimization of thermal protection systems of hypersonic vehicles. However, it is difficult to directly measure these parameters under high temperature conditions. It is an effective way to determine thermo-physical property parameters and aerodynamic heat by solving inverse problems, based on measurable or easily measured transient temperatures. However, the prediction error of these parameters may be too large, if the measurement error is large, due to the thermal inertia. To deal with this issue, an intelligent algorithm is proposed to simultaneously predict the aerodynamic heat and thermo-physical property parameters for the thermal protection systems of hypersonic vehicles, based on the temperature measurement information. It combines a genetic algorithm and a machine learning algorithm, and the genetic algorithm is employed to update the relevant parameters in the neural network. By training the neural network, the relationship among the predicted parameters and transient temperatures could be established. Thereafter, the aerodynamic heat subjected to the outer surface of the aircraft and the temperature-dependent non-linear thermo-physical property parameters could be predicted. Examples are given to verify the present algorithm. The results show that this work provides an accurate and efficient method for simultaneously determining the aerodynamic heat and thermo-physical property parameters for the thermal protection system of a hypersonic vehicle. The prediction errors of aerodynamic heat and thermo-physical property parameters are much smaller than the measurement errors, when there are relatively large measurement errors in the input data.
{"title":"A data-driven intelligent learning algorithm for simultaneous prediction of aerodynamic heat and thermo-physical property parameters","authors":"Yuxuan Li, Chengbao Sun, Zhenkun Cao, Miao Cui, Kun Liu","doi":"10.1016/j.ijthermalsci.2024.109551","DOIUrl":"10.1016/j.ijthermalsci.2024.109551","url":null,"abstract":"<div><div>It is of great importance and challenging to simultaneously determine time-varying aerodynamic heat and temperature-dependent thermo-physical property parameters with high accuracy, for the optimization of thermal protection systems of hypersonic vehicles. However, it is difficult to directly measure these parameters under high temperature conditions. It is an effective way to determine thermo-physical property parameters and aerodynamic heat by solving inverse problems, based on measurable or easily measured transient temperatures. However, the prediction error of these parameters may be too large, if the measurement error is large, due to the thermal inertia. To deal with this issue, an intelligent algorithm is proposed to simultaneously predict the aerodynamic heat and thermo-physical property parameters for the thermal protection systems of hypersonic vehicles, based on the temperature measurement information. It combines a genetic algorithm and a machine learning algorithm, and the genetic algorithm is employed to update the relevant parameters in the neural network. By training the neural network, the relationship among the predicted parameters and transient temperatures could be established. Thereafter, the aerodynamic heat subjected to the outer surface of the aircraft and the temperature-dependent non-linear thermo-physical property parameters could be predicted. Examples are given to verify the present algorithm. The results show that this work provides an accurate and efficient method for simultaneously determining the aerodynamic heat and thermo-physical property parameters for the thermal protection system of a hypersonic vehicle. The prediction errors of aerodynamic heat and thermo-physical property parameters are much smaller than the measurement errors, when there are relatively large measurement errors in the input data.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109551"},"PeriodicalIF":4.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652565","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-15DOI: 10.1016/j.ijthermalsci.2024.109549
Zhihao Zhang, Yuying Yan
Droplet evaporation is an essential physical process in industrial fields such as spray cooling and inkjet printing. With the widespread use of carbon materials, carbon-based nanofluid droplets have great potential to improve the efficiency and quality of applications in these fields. Therefore, understanding the effects of materials and external factors on the carbon-based nanofluid droplets evaporation dynamics becomes crucial. In this experimental study, the nanofluid droplets were prepared based on two common carbon-based nanomaterials, multi-walled carbon nanotubes (MWCNTs) and multi-layer graphene (MLG). The monocrystalline silicon wafer is used as the substrate, and the substrate temperature is controlled between 50 °C and 80 °C. Using the DI water droplets as a comparison, the effects of loading different carbon-based nanoparticles on wettability, evaporation modes, and heat transfer processes at the liquid-vapour interface were explored. The experimental results show that droplets loaded with MLG nanoparticles and sodium dodecyl sulfate (SDS) have the best evaporation efficiency, which can be improved by up to about 2.1 times compared with DI water. Furthermore, compared with the variable evaporation mode of the DI water droplets, the evaporation process of MLG nanofluid droplets is dominated by constant contact radius mode. At the same time, compared with DI water and MWCNTs, loaded MLG can reduce the liquid-vapour interface temperature difference by up to 3.7 °C and 1.0 °C, respectively, which effectively suppresses the evaporative cooling effect. Besides, the experimental results about the sedimentary pattern showed that MWCNTs can suppress the coffee-ring effect more effectively than MLG. Under various conditions, MLG nanoparticles can make the sedimentary pattern have greater surface roughness, which is about 1.8 times higher on average compared with MWCNTs.
{"title":"Effect of loaded carbon-based nanoparticles on the evaporation dynamics of sessile droplets","authors":"Zhihao Zhang, Yuying Yan","doi":"10.1016/j.ijthermalsci.2024.109549","DOIUrl":"10.1016/j.ijthermalsci.2024.109549","url":null,"abstract":"<div><div>Droplet evaporation is an essential physical process in industrial fields such as spray cooling and inkjet printing. With the widespread use of carbon materials, carbon-based nanofluid droplets have great potential to improve the efficiency and quality of applications in these fields. Therefore, understanding the effects of materials and external factors on the carbon-based nanofluid droplets evaporation dynamics becomes crucial. In this experimental study, the nanofluid droplets were prepared based on two common carbon-based nanomaterials, multi-walled carbon nanotubes (MWCNTs) and multi-layer graphene (MLG). The monocrystalline silicon wafer is used as the substrate, and the substrate temperature is controlled between 50 °C and 80 °C. Using the DI water droplets as a comparison, the effects of loading different carbon-based nanoparticles on wettability, evaporation modes, and heat transfer processes at the liquid-vapour interface were explored. The experimental results show that droplets loaded with MLG nanoparticles and sodium dodecyl sulfate (SDS) have the best evaporation efficiency, which can be improved by up to about 2.1 times compared with DI water. Furthermore, compared with the variable evaporation mode of the DI water droplets, the evaporation process of MLG nanofluid droplets is dominated by constant contact radius mode. At the same time, compared with DI water and MWCNTs, loaded MLG can reduce the liquid-vapour interface temperature difference by up to 3.7 °C and 1.0 °C, respectively, which effectively suppresses the evaporative cooling effect. Besides, the experimental results about the sedimentary pattern showed that MWCNTs can suppress the coffee-ring effect more effectively than MLG. Under various conditions, MLG nanoparticles can make the sedimentary pattern have greater surface roughness, which is about 1.8 times higher on average compared with MWCNTs.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109549"},"PeriodicalIF":4.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.ijthermalsci.2024.109526
Li Zhang, Huayong Zhao, Changqing Liu
Integrating lithium-ion batteries with power electronics enhances compactness, flexibility, and multifunctionality but poses thermal management challenges due to their distinct working temperatures. This paper evaluates the transient thermal characteristics of a battery-phase change materials (PCMs)-converter integrated system at both high (10C) and low (1C) battery discharge rates. A transient three-dimensional thermal model of the system is developed and experimentally validated to assess the performance of the integrated system with transient heat generation. The model goes beyond existing work, which largely focuses on steady heat generation and overheating of battery, by evaluating two key metrics: the system's delay time (), i.e. the operational duration before overheating of either the battery or the converter, and the maximum temperature difference on the battery surface (). Results indicate that increasing the PCMs' horizontal thermal conductivity (parallel to heating surfaces) consistently benefits the system by extending and reducing at both low and high discharge rates. However, increasing the vertical thermal conductivity does not always enhance . The optimum value of depends on the battery discharge rate: with a constant of 2.5 W m−1 K−1, the optimal is observed as 2542 s at = 0.4 W m−1 K−1 at a 1C discharge rate and 273 s at = 2.5 W m−1 K−1 at a 10C discharge rate. At a 1C discharge rate, can be consistently prolonged by increasing the PCM thickness. However, at a 10C discharge rate, this enhancement becomes negligible when the PCM thickness exceeds 15 mm. Thicker PCM also improves the temperature uniformity of the battery.
{"title":"Thermal management for transient integrated battery and power electronics systems using phase change materials","authors":"Li Zhang, Huayong Zhao, Changqing Liu","doi":"10.1016/j.ijthermalsci.2024.109526","DOIUrl":"10.1016/j.ijthermalsci.2024.109526","url":null,"abstract":"<div><div>Integrating lithium-ion batteries with power electronics enhances compactness, flexibility, and multifunctionality but poses thermal management challenges due to their distinct working temperatures. This paper evaluates the transient thermal characteristics of a battery-phase change materials (PCMs)-converter integrated system at both high (10C) and low (1C) battery discharge rates. A transient three-dimensional thermal model of the system is developed and experimentally validated to assess the performance of the integrated system with transient heat generation. The model goes beyond existing work, which largely focuses on steady heat generation and overheating of battery, by evaluating two key metrics: the system's delay time (<span><math><mrow><msub><mi>τ</mi><mrow><mi>s</mi><mo>−</mo><mi>d</mi></mrow></msub></mrow></math></span>), i.e. the operational duration before overheating of either the battery or the converter, and the maximum temperature difference on the battery surface (<span><math><mrow><mo>Δ</mo><mi>T</mi></mrow></math></span>). Results indicate that increasing the PCMs' horizontal thermal conductivity <span><math><mrow><msub><mi>k</mi><mrow><mi>x</mi><mi>y</mi></mrow></msub></mrow></math></span> (parallel to heating surfaces) consistently benefits the system by extending <span><math><mrow><msub><mi>τ</mi><mrow><mi>s</mi><mo>−</mo><mi>d</mi></mrow></msub></mrow></math></span> and reducing <span><math><mrow><mo>Δ</mo><mi>T</mi></mrow></math></span> at both low and high discharge rates. However, increasing the vertical thermal conductivity <span><math><mrow><msub><mi>k</mi><mi>z</mi></msub></mrow></math></span> does not always enhance <span><math><mrow><msub><mi>τ</mi><mrow><mi>s</mi><mo>−</mo><mi>d</mi></mrow></msub></mrow></math></span>. The optimum value of <span><math><mrow><msub><mi>k</mi><mi>z</mi></msub></mrow></math></span> depends on the battery discharge rate: with a constant <span><math><mrow><msub><mi>k</mi><mrow><mi>x</mi><mi>y</mi></mrow></msub></mrow></math></span> of 2.5 W m<sup>−1</sup> K<sup>−1</sup>, the optimal <span><math><mrow><msub><mi>τ</mi><mrow><mi>s</mi><mo>−</mo><mi>d</mi></mrow></msub></mrow></math></span> is observed as 2542 s at <span><math><mrow><msub><mi>k</mi><mi>z</mi></msub></mrow></math></span> = 0.4 W m<sup>−1</sup> K<sup>−1</sup> at a 1C discharge rate and 273 s at <span><math><mrow><msub><mi>k</mi><mi>z</mi></msub></mrow></math></span> = 2.5 W m<sup>−1</sup> K<sup>−1</sup> at a 10C discharge rate. At a 1C discharge rate, <span><math><mrow><msub><mi>τ</mi><mrow><mi>s</mi><mo>−</mo><mi>d</mi></mrow></msub></mrow></math></span> can be consistently prolonged by increasing the PCM thickness. However, at a 10C discharge rate, this enhancement becomes negligible when the PCM thickness exceeds 15 mm. Thicker PCM also improves the temperature uniformity of the battery.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109526"},"PeriodicalIF":4.9,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.ijthermalsci.2024.109512
Surip Widodo , Nandy Putra , Anhar Riza Antariksawan , Mulya Juarsa
This research aims to develop a passive residual heat removal system (PRHR) for 300 MW thermal power light water reactors (LWRs) utilizing a novel two-phase thermosyphon configuration. The proposed PRHR design includes an evaporator section immersed in the steam path of the PRHR, enabling efficient heat transfer directly from the steam source. The primary objectives are to investigate the thermal performance characteristics of the two-phase thermosyphon when operating in the steam environment of the PRHR, and to assess the effectiveness of direct heat extraction from the PRHR steam in reducing the size of heat exchange equipment required for long-term heat removal. The novelty of this research lies in the development of a conceptual PRHR design that extends passive heat removal capabilities beyond the conventional 72-h operational window. While existing PRHR systems necessitate operator intervention to prolong functionality, the proposed configuration leverages the inherent advantages of two-phase thermosyphons, offering sustained passive heat removal with enhanced thermal conductivity and efficiency. To support this novel concept, the research involves experimental evaluations of the two-phase thermosyphon's thermal performance when subjected to steam heat sources ranging from 1 to 3 bar. Experimental data will validate numerical models, enabling the determination of design parameters for the PRHR configuration specified for 300 MW thermal power LWRs. This comprehensive research initiative represents a significant step toward enhancing the safety and reliability of PRHR systems for advanced nuclear reactors.
{"title":"Innovative two-phase thermosyphon-based PRHR system for prolonged passive heat removal in light water reactors","authors":"Surip Widodo , Nandy Putra , Anhar Riza Antariksawan , Mulya Juarsa","doi":"10.1016/j.ijthermalsci.2024.109512","DOIUrl":"10.1016/j.ijthermalsci.2024.109512","url":null,"abstract":"<div><div>This research aims to develop a passive residual heat removal system (PRHR) for 300 MW thermal power light water reactors (LWRs) utilizing a novel two-phase thermosyphon configuration. The proposed PRHR design includes an evaporator section immersed in the steam path of the PRHR, enabling efficient heat transfer directly from the steam source. The primary objectives are to investigate the thermal performance characteristics of the two-phase thermosyphon when operating in the steam environment of the PRHR, and to assess the effectiveness of direct heat extraction from the PRHR steam in reducing the size of heat exchange equipment required for long-term heat removal. The novelty of this research lies in the development of a conceptual PRHR design that extends passive heat removal capabilities beyond the conventional 72-h operational window. While existing PRHR systems necessitate operator intervention to prolong functionality, the proposed configuration leverages the inherent advantages of two-phase thermosyphons, offering sustained passive heat removal with enhanced thermal conductivity and efficiency. To support this novel concept, the research involves experimental evaluations of the two-phase thermosyphon's thermal performance when subjected to steam heat sources ranging from 1 to 3 bar. Experimental data will validate numerical models, enabling the determination of design parameters for the PRHR configuration specified for 300 MW thermal power LWRs. This comprehensive research initiative represents a significant step toward enhancing the safety and reliability of PRHR systems for advanced nuclear reactors.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109512"},"PeriodicalIF":4.9,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.ijthermalsci.2024.109530
Changzhong Li , Chenglong Wang , Yanyu Sun , Ronghua Chen , Wenxi Tian , Guanghui Su , Suizheng Qiu
Helium is utilized as coolant in high temperature gas cooled reactors. Rectangular narrow slit channels are commonly present in the core. The flow and heat transfer properties of helium significantly affect the core temperature and flow distribution. This paper experimentally investigates the flow and heat transfer properties of high temperature helium in rectangular narrow slit channel. The Reynolds numbers ranged from 468 to 9357, the temperature ratio of wall to bulk from 0.91 to 1.22, the helium outlet temperature up to 945 K, and the maximum heat flux density up to 0.101 MW/m2. In the experiment, the total and local convective heat transfer coefficients, along with the friction factors, are measured. Correlation equations for the Nusselt number and friction factor with respect to Reynolds number are derived. The primary findings are as below: the friction factors of helium in rectangular narrow slit channels are significantly larger than those calculated by current empirical correlations. In the turbulent zone, the measured local Nusselt numbers are in excellent accordance with the Gnielinski correlation; however, a significant discrepancy exists in the laminar zone. New flow heat transfer correlation equations are proposed on the bases of experimental data. Upon comparison, the total Nusselt numbers fall in the error of 10 %, and almost all local Nusselt numbers and the friction factors fall in the error of 20 %.
{"title":"Experimental investigation on flow and heat transfer characteristics of helium in rectangular narrow slit channel","authors":"Changzhong Li , Chenglong Wang , Yanyu Sun , Ronghua Chen , Wenxi Tian , Guanghui Su , Suizheng Qiu","doi":"10.1016/j.ijthermalsci.2024.109530","DOIUrl":"10.1016/j.ijthermalsci.2024.109530","url":null,"abstract":"<div><div>Helium is utilized as coolant in high temperature gas cooled reactors. Rectangular narrow slit channels are commonly present in the core. The flow and heat transfer properties of helium significantly affect the core temperature and flow distribution. This paper experimentally investigates the flow and heat transfer properties of high temperature helium in rectangular narrow slit channel. The Reynolds numbers ranged from 468 to 9357, the temperature ratio of wall to bulk from 0.91 to 1.22, the helium outlet temperature up to 945 K, and the maximum heat flux density up to 0.101 MW/m<sup>2</sup>. In the experiment, the total and local convective heat transfer coefficients, along with the friction factors, are measured. Correlation equations for the Nusselt number and friction factor with respect to Reynolds number are derived. The primary findings are as below: the friction factors of helium in rectangular narrow slit channels are significantly larger than those calculated by current empirical correlations. In the turbulent zone, the measured local Nusselt numbers are in excellent accordance with the Gnielinski correlation; however, a significant discrepancy exists in the laminar zone. New flow heat transfer correlation equations are proposed on the bases of experimental data. Upon comparison, the total Nusselt numbers fall in the error of 10 %, and almost all local Nusselt numbers and the friction factors fall in the error of 20 %.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109530"},"PeriodicalIF":4.9,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.ijthermalsci.2024.109517
Guohu Liang , Zhen Zhang , Shanshan Bu , Hanzhou Liu , Deqi Chen
Advanced reactors adopt the cavity injection system (CIS) combining forced and natural circulation to implement the IVR-ERVC (in-vessel retention by external reactor vessel cooling) after severe accidents, which improves the inherent safety. The Critical heat flux (CHF) is important to assess the cooling capacity of CIS. The numerical method based on the Euler two-fluid model and the non-equilibrium wall boiling model is applied to study the subcooled flow boiling characteristics and the influence of different factors on the CHF under natural circulation conditions. It is found that the heating wall temperature is mainly affected by the heat flux and vapor migration. Vapor accumulates toward the heating wall due to the curved channel and the buoyancy, and the vapor-phase convective heat transfer dominates after the local void fraction rises drastically when the heat flux is large enough, leading to a significant reduction of the heat transfer capacity and triggering the boiling crisis. The heat transfer coefficient decreases at the 0∼45° region and increases at 45∼90°region. Increasing the subcooling and the pressure can enhance the CHF, but it will weaken the circulating driving force and reduce the mass flow rate. Raising the circulation height and shortening the channel width can improve the circulating flow rate and turbulence mixing intensity to enhance the CHF. Meanwhile, a correlation integrating multiple influencing factors is proposed to predict the CHF under natural circulation conditions. The mean relative deviation between the predicted and experimental CHF is only 9.63%, and the predictive accuracy and applicable scope are both improved remarkably compared with the existing correlations. This work can provide a deep understanding of the flow boiling characteristics of natural circulation and provide a reference for optimizing the ERVC strategy.
{"title":"CFD study on flow-boiling characteristics and predicting critical heat flux under natural circulation conditions of IVR-ERVC","authors":"Guohu Liang , Zhen Zhang , Shanshan Bu , Hanzhou Liu , Deqi Chen","doi":"10.1016/j.ijthermalsci.2024.109517","DOIUrl":"10.1016/j.ijthermalsci.2024.109517","url":null,"abstract":"<div><div>Advanced reactors adopt the cavity injection system (CIS) combining forced and natural circulation to implement the IVR-ERVC (in-vessel retention by external reactor vessel cooling) after severe accidents, which improves the inherent safety. The Critical heat flux (CHF) is important to assess the cooling capacity of CIS. The numerical method based on the Euler two-fluid model and the non-equilibrium wall boiling model is applied to study the subcooled flow boiling characteristics and the influence of different factors on the CHF under natural circulation conditions. It is found that the heating wall temperature is mainly affected by the heat flux and vapor migration. Vapor accumulates toward the heating wall due to the curved channel and the buoyancy, and the vapor-phase convective heat transfer dominates after the local void fraction rises drastically when the heat flux is large enough, leading to a significant reduction of the heat transfer capacity and triggering the boiling crisis. The heat transfer coefficient decreases at the 0∼45° region and increases at 45∼90°region. Increasing the subcooling and the pressure can enhance the CHF, but it will weaken the circulating driving force and reduce the mass flow rate. Raising the circulation height and shortening the channel width can improve the circulating flow rate and turbulence mixing intensity to enhance the CHF. Meanwhile, a correlation integrating multiple influencing factors is proposed to predict the CHF under natural circulation conditions. The mean relative deviation between the predicted and experimental CHF is only 9.63%, and the predictive accuracy and applicable scope are both improved remarkably compared with the existing correlations. This work can provide a deep understanding of the flow boiling characteristics of natural circulation and provide a reference for optimizing the ERVC strategy.</div></div>","PeriodicalId":341,"journal":{"name":"International Journal of Thermal Sciences","volume":"209 ","pages":"Article 109517"},"PeriodicalIF":4.9,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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