表面结构对喷雾冷却临界热流密度的影响

Effects of Surface Structures on Critical Heat Flux in Spray Cooling

在闭式循环喷雾冷却系统上,以蒸馏水为工质,研究了表面结构、喷雾流量对喷雾冷却临界热流密度的影响。结果表明,相较于光滑表面,微槽表面可提升临界热流密度;因具有适当的槽深(0.3mm)和较窄的槽宽(0.2mm),No.2槽面的临界热流密度最大,在流量为18.0m L/min时,临界热流密度为175.7W/cm2,比光滑表面提升了59.1%,对应的液体蒸发率达91.4%;增加喷雾流量能大幅提升临界热流密度,特别是对槽面而言更是如此;流量从13.0m L/min增至23.0m L/min时,No.6槽面的临界热流密度由130.7W/cm2增至212.4W/cm2,相对增加了62.5%,同样情况下,光滑表面临界热流密度仅增加了43.6%。表面开槽可有效阻止液滴滚离待冷面,延长液滴停留时间,这是微槽面临界热流密度更大的根本原因。

Experiments were conducted to study the effects of surface geometry structures and spray flow rate on critical heat flux （CHF） of spray cooling with distilled water as the working fluid. Test results show that micro-grooved surfaces have much lar- ger CI-IF in comparison to the smooth flat surface. Because of its suitable groove depth （0.3mm） and much narrower groove width （0.2mm）, No. 2 surface have a maximum CHF of 175.7 W/cm2, which increases 59.1% relative to the flat surface and whose e- vaporation efficiency is 91.4% ,when the flow rate is 18.0mL/min. CHF can obviously increase with increasing the flow rate, es- pecially for the micro -grooved surfaces. When the flow rate nses from 13.0mL/min to 23. OmL/min,CHF of No. 6 surface in- creases from 130.7 W/cm2 to 212.4 W/cm2 and the relative CHF enhancement is up to 62.5%. At the same range of flow rates, the smooth flat surface only achieves CHF enhancement of 43.6%. The grooves on surface can prevent droplets from leaving sur- faces and increase contact time,which enhance CHF for micr-grooved surfaces.