R600a喷雾冷却系统换热过程

Heat transfer process of R600a spray cooling system

以R600a压力式封闭系统喷雾冷却过程为研究对象,对其换热过程进行分析。对液滴撞击热面后的状态进行建模,分析了其运动状态。通过忽略液膜的对流换热,引入韦伯数来简化并修正雾滴与热源表面的对流换热系数关联式;借鉴二次成核理论,通过单位时间内,单位面积上覆盖的雾滴数量对核态沸腾换热系数关联式修正。通过上述分析,以对流换热和核态沸腾换热两种机理为中心,建立了新的换热系数关联式。通过与其他文献的关联式、实验测量值进行比较、不同工质进行比较、不同实验系统比较,发现该式预测值和实验测量值偏差在±20%以内,能够很好地预测压力式封闭系统喷雾冷却过程的换热系数。

A closed pressure atomization spray cooling system with R6OOa was used to study the heat transfer process of spray cooling. The modeling of droplets impinging on hot surface was built and the moving state was analyzed. The convective heat transfer of liquid film was ignored and Weber number was used to amend the heat transfer convection coefficient between the droplets and the heater surface. Furthermore, the theory of secondary nucleate boiling was referenced to amend empirical correla tion of nucleate boiling. Based on the above analysis, empirical correlations of heat transfer coefficient were built by considering the convection and nucleate boiling. By comparing to the correlations and experimental measurements of other researchers, and comparing to different coolants and experimental systems, we found that the errors of the predicted values and the experimental measurements were within ±20%. So the empirical correlation can well predict the heat transfer coefficient of closed pressure spray cooling system.