搭建以R134a为制冷工质的闭式喷雾冷却试验台，试验研究喷雾冷却瞬态传热过程，建立了准确描述其传热过程的试验曲线，分析了蒸发压力对传热性能的影响，并阐述了每个瞬态传热阶段的传热机理。试验蒸发压力变化范围为0.207~0.331 MPa，流量范围为0.140~0.164 L/min。结果表明:膜态沸腾区在瞬态冷却过程中所占时间最长，且表面温度冷却速率保持在0.10 ℃/s，热流密度维持在20 W/cm2以下，故穿越膜态沸腾区的耗时决定着喷雾冷却瞬态过程的冷却速率；增加蒸发压力，可以提升冷却速率，当蒸发压力从0.207 MPa增加到0.331 MPa时，表面温度从130 ℃冷却至30 ℃所需的时间从508 s降至381 s；喷雾冷却瞬态过程在过渡沸腾区存在表面温度突变点，随着蒸发压力提高，突变点对应温度增加。

A closedloop spray cooling system with R134a as working medium was set up.The transient heat transfer process of spray cooling was studied experimentally and the cooling curve was accurately described.Also,the influence of evaporation pressure on the heat transfer performance was analyzed,and the heat transfer mechanism of each stage was described.Experimental evaporation pressure ranged from 2.07 bar to 3.31 bar and the flow rate ranged from 0.14 L/min to 0.164 L/min.The results showed that the film boiling regime takes the longest time in the whole transient cooling process,and the cooling rate of surface temperature remains at 0.10 ℃/s,while the heat flux maintains below 20 W/cm2.The transient spray cooling rate is determined by the time of going through film boiling regime,and can be improved by increasing the evaporation pressure.When the evaporation pressure increases from 2.07 bar to 3.31 bar,the time required to cool the surface temperature from 130 ℃ to 30 ℃ decreases from 508 s to 381 s.Besides,there is a surface temperature discontinuity in the transition boiling regime of transient spray cooling process,and the corresponding temperature can be improved by increasing the evaporation pressure.

TK124

江苏省自然科学基金（BK20180960）