方柱微结构表面射流-流动沸腾强化换热

采用长×宽×厚为10 mm×10 mm×0.5 mm的硅片来模拟实际芯片散热,通过干腐蚀技术在其表面加工出宽×高分别为50μm×60μm,50μm×120μm的方柱微结构,实验研究了方柱微结构在射流冲击下的流动沸腾换热性能。过冷度为25℃和35℃,横流速度V_c为0.5,1.0,1.5 m/s,喷射速度V_j为0～2 m/s,冷却工质为FC-72。实验结果和同工况下的光滑表面作了对比。结果表明,方柱微结构由于换热面积的增加从而表现出优于光滑表面的强化换热性能,增加过冷度和提高V_c以及V_j都提高了芯片在高热流密度下的换热性能,但随着V_c的增加,射流冲击的强化作用减弱,低流动高喷射的强化效果最为明显。方柱肋片效率随着热流密度的增加而减小,随着V_c(V_j)增加,方柱肋片效率也逐渐下降,但降幅随着V_c的增加而减小。

Flow-Jet Boiling Heat Transfer Enhancement on Micro-Pin-Finned Chips

For high-efficiently solving the power dissipation problem of electronic components with high heat flux,experimental study of the flow-jet combined boiling heat transfer on silicon chips was conducted.The micro-pin-fins with dimensions of 50×60μm²,50×120μm²（thickness x height） were fabricated on the chip surfaces by the dry etching technique.The experiments were made at three different crossflow velocities V_c（0.5,1.0,1.5 m/s） and different jet velocities V_j（0～2 m/s） with two liquid subcooling△T_sub（25℃and 35℃）.A smooth surface was also tested for comparison. The micro-pin-fins showed a considerable heat transfer enhancement due to increase in effective heat transfer surface area.The heat transfer enhancement at high heat flux region can be achieved by increasing liquid subcooling and velocities.For a fixed flow mass rate,adopting low V_c large V_j combination may obtain a high heat flux.The fin efficiencyη_f decreases as V_c（V_j） increases,but the increment decreases as V_c increases.Besides,the fin efficiencyη_f also decreases as the heat flux q increases.