微针肋结构大过冷度强化沸腾传热实验研究

Experimental Study on Enhanced Boiling Heat Transfer on Micro-pin-fin Structures at High Degrees of Subcooling

高热流密度电子设备发热功率日益增加,需要新的高效冷却技术保障其安全运行,采用大过冷度流体与微针肋结构结合的方式是提升冷却能力的一种新思路。本文实验观测了微针肋结构过冷沸腾现象,测试了不同过冷度(50、60、75、95℃)对表面传热系数与临界热流密度的影响,确定了大过冷度下微针肋结构相比光滑结构表面传热系数的强化比例,研究了微针肋结构过冷沸腾强化传热机理。结果表明:当热流密度超过200 W/cm^(2)时,微针肋结构过冷沸腾换热表面传热系数随过冷度增大而增大;微针肋结构临界热流密度随过冷度上升而上升,当过冷度由50℃升至95℃,临界热流密度由228 W/cm^(2)升至400 W/cm^(2)以上;微针肋结构表面传热系数均比同工况下的光滑结构表面传热系数大,微针肋结构的强化传热效果在大热流密度、大过冷度下更为显著,当热流密度为250 W/cm^(2)、过冷度为95℃时,强化比例为1.28。

In response to the power increase in electronic devices with high heat flux density,new efficient cooling technologies should be developed to ensure the safe operation of these electronic devices.The application of micro-pin-fin structures under high-degree subcooled boiling is a promising way of enhancing the cooling capacity.In this study,subcooled boiling on a micro pin-fin surface was observed,and the effects of the subcooled temperature on the heat transfer coefficient and critical heat flux were measured.Moreover,the heat transfer coefficients of the micro-pin-fin structure were compared with those of a smooth surface,and the heat transfer enhancement mechanism of the micro-pin-fin structure was investigated.The results show that the heat transfer coefficient of the micro-pin-fin surface increases with an increase in the subcooled degree when the heat flux is greater than 200 W/cm^(2).The critical heat flux increases from^(2)28 W/cm^(2) to more than 400 W/cm^(2) when the subcooled degree increases from 50℃to 95℃.The heat transfer coefficient of the micro-pin-fin surface is always larger than that of the smooth surface under the same working conditions,and the effect of the micro-pin-fin surface is more obvious under high degrees of subcooling and high heat flux.The enhancement factor is 1.28 when the heat flux is 250 W/cm^(2) and the degree of subcooling is 95℃.