随着功率模块集成化程度的提高,其散热结构优化已成为研发中的关键。拓扑优化可通过变换散热器形貌、结构来最大化地提升散热效果,因此受到了广泛关注。但在拓扑优化过程中,每步迭代均需要计算模块与散热器温度分布,占用较庞大的计算资...随着功率模块集成化程度的提高,其散热结构优化已成为研发中的关键。拓扑优化可通过变换散热器形貌、结构来最大化地提升散热效果,因此受到了广泛关注。但在拓扑优化过程中,每步迭代均需要计算模块与散热器温度分布,占用较庞大的计算资源和计算时间。为加速传统散热器拓扑优化进程,在基于传统固体各向同性材料惩罚SIMP(solid isotropic material with penalization)散热器拓扑优化方法的基础上,提出一种嵌套神经网络NN(neural network)同步学习的快速迭代方法。首先,构建散热器基于编码器-解码器结构的NN预测模型,即基于散热器形貌迭代进化过程实现优化结构的快速预测;其次,将NN模型与散热器SIMP拓扑优化流程相嵌套,利用迭代过程中的中间形貌同步训练NN;最后,针对单芯片、两芯片模块结构,对比所提方法与传统迭代方法的拓扑优化结果,验证了所提NN同步学习方法的准确性和快速性。展开更多
In this paper, thermal characteristics of the high-power LED spot lamp are reported. The emphasis is placed upon optimizing design of the heat sink of LED spot lamp using the optimization module and the orthogonal-exp...In this paper, thermal characteristics of the high-power LED spot lamp are reported. The emphasis is placed upon optimizing design of the heat sink of LED spot lamp using the optimization module and the orthogonal-experiment method. Results demonstrate that the weight of the heat sink is decreased to 46.1% of that for the initial structure, and the influence of each factor on junction temperature and weight of the heat sink is acquired by range analysis. Finally, the influence of ambient temperature and natural convection coefficient on the LED maximum temperature is analyzed. The results and the optimizing methodology are of great importance to the thermal design of LED lamps.展开更多
Double layer micro-channel heat sink(DLMCHS) has been widely used in various electronic devices; however, the existence of the nonuniform thermal strain distribution in actual operation has adverse effect on the overa...Double layer micro-channel heat sink(DLMCHS) has been widely used in various electronic devices; however, the existence of the nonuniform thermal strain distribution in actual operation has adverse effect on the overall stability. In this paper, two optimized designs of DLMCHS with cutting baffles on top and bottom layers are presented based on the traditional DLMCHS. The heat transfer and thermal stress performance are numerically analyzed and compared with the traditional DLMCHS. The results indicate that cutting baffles of micro-channels remarkably improves heat transfer and thermal stress performance. The optimized design with cutting baffles on the bottom layer decreases thermal strain but deteriorates heat transfer performance. The model with cutting baffles on the top layer has better combined thermal strain and heat transfer performance, which reduces thermal strain by about 1.5 times and enhances heat transfer by about 26.5%. For the design with cutting baffles on the top board, adding metal foam in the inlet collector can decrease the total minimum thermal strain by 51.4% and maximum temperature by 1.4 K, and increase the Nusselt number by 15%. These results indicate that DLMCHS with cutting baffles on the top layer has great potential for thermal managements on electronic devices with high power density.展开更多
An appropriate microenvironment for preserving cultural relics is essential,and the air-water direct contact tech-nology is utilized to create the microenvironment recently.The influence of a deflector in a tank was n...An appropriate microenvironment for preserving cultural relics is essential,and the air-water direct contact tech-nology is utilized to create the microenvironment recently.The influence of a deflector in a tank was numerically investigated based on uniform design method to improve the heat and mass transfer and pressure drop perfor-mance of the air-water direct tank.In this study,a simplified CFD-based model was established and validated between airstream and water surface within the tank,to analyze the heat and mass transfer and pressure drop processes.Meanwhile,regression models of the heat transfers rate,mass transfer rate and pressure drop were developed by uniform design method based on three parameters:installation position,tilt angle,and height of the deflector,in order to analyze the influences of these three parameters on the heat and mass transfer and pressure drop of the tank.Finally,all three optimal structural parameters of the deflector were obtained based on the proposed comprehensive evaluation index using a genetic algorithm.The results showed that the model established for air-water direct contact adopted well to predict the heat and mass transfer and pressure drop per-formance between airstream and still water surface.Furthermore,the results found that the flow field inside the water tank was affected by the deflector’s structure,which affected the heat and mass transfer performance.The simulation results suggested that the deflector’s optimal structural parameters are 8 mm of installation position,88°of tilt angle and 19 mm of height,respectively,within a given extent in this study.展开更多
文摘随着功率模块集成化程度的提高,其散热结构优化已成为研发中的关键。拓扑优化可通过变换散热器形貌、结构来最大化地提升散热效果,因此受到了广泛关注。但在拓扑优化过程中,每步迭代均需要计算模块与散热器温度分布,占用较庞大的计算资源和计算时间。为加速传统散热器拓扑优化进程,在基于传统固体各向同性材料惩罚SIMP(solid isotropic material with penalization)散热器拓扑优化方法的基础上,提出一种嵌套神经网络NN(neural network)同步学习的快速迭代方法。首先,构建散热器基于编码器-解码器结构的NN预测模型,即基于散热器形貌迭代进化过程实现优化结构的快速预测;其次,将NN模型与散热器SIMP拓扑优化流程相嵌套,利用迭代过程中的中间形貌同步训练NN;最后,针对单芯片、两芯片模块结构,对比所提方法与传统迭代方法的拓扑优化结果,验证了所提NN同步学习方法的准确性和快速性。
基金supported by the Natural Science Foundation of Zhejiang Province (No.Y104436)the Science and Technology Fund Projects of Zhejiang Province (No.2008C21158)the Innovative Basement Project of Graduate Education of Zhejiang Province
文摘In this paper, thermal characteristics of the high-power LED spot lamp are reported. The emphasis is placed upon optimizing design of the heat sink of LED spot lamp using the optimization module and the orthogonal-experiment method. Results demonstrate that the weight of the heat sink is decreased to 46.1% of that for the initial structure, and the influence of each factor on junction temperature and weight of the heat sink is acquired by range analysis. Finally, the influence of ambient temperature and natural convection coefficient on the LED maximum temperature is analyzed. The results and the optimizing methodology are of great importance to the thermal design of LED lamps.
基金supported in part by the National Natural Science Foundation of China (No. 51676208)the Fundamental Research Funds for the Central Universities (No. 18CX07012A)
文摘Double layer micro-channel heat sink(DLMCHS) has been widely used in various electronic devices; however, the existence of the nonuniform thermal strain distribution in actual operation has adverse effect on the overall stability. In this paper, two optimized designs of DLMCHS with cutting baffles on top and bottom layers are presented based on the traditional DLMCHS. The heat transfer and thermal stress performance are numerically analyzed and compared with the traditional DLMCHS. The results indicate that cutting baffles of micro-channels remarkably improves heat transfer and thermal stress performance. The optimized design with cutting baffles on the bottom layer decreases thermal strain but deteriorates heat transfer performance. The model with cutting baffles on the top layer has better combined thermal strain and heat transfer performance, which reduces thermal strain by about 1.5 times and enhances heat transfer by about 26.5%. For the design with cutting baffles on the top board, adding metal foam in the inlet collector can decrease the total minimum thermal strain by 51.4% and maximum temperature by 1.4 K, and increase the Nusselt number by 15%. These results indicate that DLMCHS with cutting baffles on the top layer has great potential for thermal managements on electronic devices with high power density.
基金This present work was supported by the National Natural Science Foundation of China(51636007)the N Cultural Relics Protection Science and Technology Program of Zhejiang Province(No.2020009).No conflict of interest exists in submitting this manuscript,and all au-thors approve the manuscript for publication.
文摘An appropriate microenvironment for preserving cultural relics is essential,and the air-water direct contact tech-nology is utilized to create the microenvironment recently.The influence of a deflector in a tank was numerically investigated based on uniform design method to improve the heat and mass transfer and pressure drop perfor-mance of the air-water direct tank.In this study,a simplified CFD-based model was established and validated between airstream and water surface within the tank,to analyze the heat and mass transfer and pressure drop processes.Meanwhile,regression models of the heat transfers rate,mass transfer rate and pressure drop were developed by uniform design method based on three parameters:installation position,tilt angle,and height of the deflector,in order to analyze the influences of these three parameters on the heat and mass transfer and pressure drop of the tank.Finally,all three optimal structural parameters of the deflector were obtained based on the proposed comprehensive evaluation index using a genetic algorithm.The results showed that the model established for air-water direct contact adopted well to predict the heat and mass transfer and pressure drop per-formance between airstream and still water surface.Furthermore,the results found that the flow field inside the water tank was affected by the deflector’s structure,which affected the heat and mass transfer performance.The simulation results suggested that the deflector’s optimal structural parameters are 8 mm of installation position,88°of tilt angle and 19 mm of height,respectively,within a given extent in this study.
