闭式循环喷雾冷却蒸发换热特性试验研究

Experimental Study on Evaporative Heat Transfer Characteristics of Spray Cooling in a Closed Loop System

在闭式循环喷雾冷却试验系统上,以蒸馏水为工质,研究了喷雾流量、表面结构对喷雾冷却换热性能的影响。从对流换热和蒸发换热比例关系的角度,对试验数据进行了整理。结果表明,热流密度、换热系数、对流热流密度均随表面温度和流量的增加而增加;但蒸发换热份额却随表面温度的升高和流量的降低而增加。槽面强化换热的机理在于其较高的蒸发换热能力,但流量越大强化换热效果愈弱。分别对光面和槽面的数据进行了无量纲拟合,得到了各自反映蒸发换热特性的无量纲准则方程,可方便用于工程设计。

With water as the working fluid,experiments on evaporative heat transfer characteristic of spray cooling were performed in a closed loop system.Through changing the flow of spray and surface structure,the relationship between convective and evaporative heat transfer was discovered at first time.Test results indicated the heat flux,the heat transfer coefficient and the convective heat flux increased with an increase of surface temperature and the flow of spray,while the ratio of evaporative heat transfer grew when surface temperature increased and the flow of spray decreased.The grooved surface had higher heat transfer ability than the smooth surface due to its better evaporative heat transfer characteristics,but the bigger the flow of spray was,the smaller the consequent of enhanced heat transfer was.Non-dimensional criterion equations about two surfaces were derived individually,in which the influence of surface temperature on evaporative heat transfer was considered.