판형 마이크로 진동형 히트파이프에 대한 실험 및 이론적 연구

Abstract

Electronic devices are gradually becoming smaller in size and the heating spot is also becoming smaller. The Micro Pulsating Heat Pipe(MPHP) is an efficient device to dissipate heat from the miniaturized heating surface. In the present study, experiments and simulations were conducted in order to design high performance MPHP. Thermal performance experiments were conducted to investigate the variables that can influence the design of MPHP. The temperature of the heating part was fixed at 75℃ and the temperature of cooling part was fixed at 23℃. The MPHPs for test were made by micro milling technology. MPHPs were machined in two types of square channels with a channel side length of 800 and 600 μm. The number of turns were five and nine. For working fluid, FC-72 was employed in this study because of its chemically stable characteristics for electronic device. The base charging ratio was 60% and an optimum charging ratio was saught. Flow visualization using high_speed camera was recorded to study the flow motion. The circulation and pulsating motions were observed in the experiment. Heat transfer rate increased as the channel size increased or the number of turns increased. The optimum charging ratio for high cooling performance was found to be 60%. Copper plate MPHP showed better heat transfer performance than that of the aluminum plate MPHP. When MPHP alignment angle was found to be vertical, the performance of heat transfer was higher. Numerical simulations of MPHP using ANSYS Fluent were carried out. The calculated heat transfer reat were in good agreement with the experimental data. The simulation results also provided an insight to better understand the mechanism of MPHP