Experimental investigation of the thermal performance of a heat sink with U-shaped heat pipes

Author(s):  
Yaxiong Wang ◽  
Jinrong Wang ◽  
Xiufen He ◽  
Jianguo Duan
Author(s):  
Hsiang-Sheng Huang ◽  
Jung-Chang Wang ◽  
Sih-Li Chen

This article provides an experimental method to study the thermal performance of a heat sink with two pairs (outer and inner pair) of embedded heat pipes. The proposed method can determine the heat transfer rate of the heat pipes under various heating power of the heat source. A comprehensive thermal resistance network of the heat sink is also developed. The network estimates the thermal resistances of the heat sink by applying the thermal performance test result. The results show that the outer and inner pairs of heat pipes carries 21% and 27% of the total heat transfer rate respectively, while 52% of the heating power is dissipated from the base plate to the fins. The dominated thermal resistance of the heat sink is the base to heat pipes resistance which is strongly affected by the thermal performance of the heat pipes. The total thermal resistance of the heat sink shows the lowest value, 0.23°C/W, while the total heat transfer rate of the heat sink is 140W and the heat transfer rate of the outer and inner pairs of heat pipes is 30W and 38 W, respectively.


2017 ◽  
Vol 148 ◽  
pp. 1332-1345 ◽  
Author(s):  
Heng Tang ◽  
Yong Tang ◽  
Baoshan Zhuang ◽  
Gong Chen ◽  
Shiwei Zhang

Author(s):  
Victor Adrian Chiriac

The transient thermal behavior of a complex testing system including multiple fans, a mixing enclosure, Cu inserts and a leaded package dissipating large amounts of power over short time durations is evaluated via numerical simulations. The system performance is optimized with heat sink/fan structure for device efficient operation under constant powering. The study provides meaningful understanding and prediction of a transient powering scenario at high powering levels, evaluating the impact of alternative cooling fan/heat pipe configurations on the thermal performance of the system. One design is chosen due to its effective thermal performance and assembly simplicity, with the package embedded in heat sink base with multiple (5) heat pipes. The peak temperature reached by the modified design with 4 cooling fans is ∼95°C, with the corresponding Rja thermal resistance ∼0.58°C/W. For the transient study (with embedded heat pipes and 4 fans), after one cycle, both peak temperature (at 45 s) and the end temperature (at 49 s) decrease as compared to the previous no heat pipe/single fan case (especially the end temperature reduces by ∼16%). The temperature drop between peak and end for each cycle is ∼80.2°C, while the average power per transient cycle is ∼31.27W. With this power, the design with 5 perpendicular heat pipes, 4 fans and insert reaches a steady state peak temperature of ∼98°C. Applying the superposition principle, the maximum transient temperature after a large number of operating cycles will not exceed ∼138.1°C, satisfying the thermal budget under the current operating conditions. The benefit of the study is related to the possibility to extract the maximum/minimum temperatures for a real test involving a large number of heating-cooling cycles, yet maintaining the initial and peak temperatures within a certain range for the optimal operation of the device. The flow and heat transfer fields are thoroughly investigated: using a combination of numerical and analytical study, the thermal performance of the device undergoing large number of periodic thermal cycles is predicted. Further comparison between measurement and simulation results reveals good agreement.


Author(s):  
Victor Adrian Chiriac ◽  
Tien-Yu Tom Lee

A numerical study was conducted to model the transient thermal behavior of a complex testing system including multiple fans, a mixing enclosure, copper inserts and a leaded package dissipating large amounts of power over short time durations. The system is optimized by choosing appropriate heat sink/fan structure for the efficient operation of the device under constant powering. The intent of the study is to provide a better understanding and prediction of a transient powering scenario at high powering levels, while evaluating the impact of alternative cooling fan/heat pipe designs on the thermal performance of the testing system. One design is chosen due to its effective thermal performance and assembly simplicity, with the package embedded in heat sink base with multiple (5) heat pipes. The peak temperature reached by the modified design with 4 cooling fans is ~95°C, with the corresponding Rja thermal resistance ~0.58°C/W. For the transient study (with embedded heat pipes and 4 fans), after one cycle, both peak temperature (at 45 s) and the end temperature (at 49 s) decrease as compared to the previous no heat pipe/single fan case (the end temperature reduces by ~16%). The temperature drop between peak and end for each cycle is ~80.2°C, while the average power per transient cycle is ~31.27W. With this power, the design with 5 perpendicular heat pipes, 4 fans and insert reaches a steady state peak temperature of ~98°C. Applying the superposition principle to the steady state value and 40.1°C fluctuation, the maximum transient temperature after a large number of cycles will not exceed ~138.1°C, satisfying the thermal budget under the current operating conditions. The benefit of the study is related to the possibility to extract the maximum and minimum temperatures for a real test involving a large number of heating-cooling cycles, yet maintaining the initial and peak temperatures within a certain range for the optimal operation of the device. The flow and heat transfer fields are investigated; using a combination of numerical and analytical methods, the thermal performance of the device undergoing large number of periodic thermal cycles is predicted. The comparison between measurement and simulation shows good agreement.


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