脉冲式喷雾冷却传热性能实验研究

Experimental study on heat transfer performance of pulsed spray cooling

搭建了以水为工质的喷雾冷却系统,通过变频器调整工质喷雾周期和占空比,获取其传热性能变化规律,研究结果表明:当加热功率小于1 000 W时脉冲喷雾冷却系统存在最佳喷雾周期,当加热功率增至1 200 W喷雾冷却传热系数始终低于连续喷雾;随着加热功率增加不同占空比均对应最优工况,当占空比为0.5,加热功率1 000 W时,表面传热系数为4.02 W/(cm^(2)·℃),比连续喷雾时增大了80.1%;随着占空比的减小,槽道表面传热系数呈现先增大后减小的趋势,而光滑表面呈现增大趋势;采用脉冲式喷雾时不仅可以缩短达到热平衡的时间而且工质量也有大幅度的减少,当喷雾流量为0.45 L/min,达到热平衡时占空比0.4工况比连续喷雾节省了80.9%的工质。

A spray cooling system with water as the working medium was built,and the spray period and duty ratio of working medium were adjusted by a frequency converter to obtain the change law of its heat transfer performance.The results show that when the heating power is less than 1000 W,the pulse spray cooling system has an optimal spray period,and when the heating power is increased to 1200 W,the heat transfer coefficient of spray cooling is always lower than that of continuous spray cooling.When the duty cycle is 0.5 and the heating power is 1000 W,the surface heat transfer coefficient is 4.02 W/(cm^(2)·℃),which is 80.1%higher than that of continuous spraying.As the duty cycle decreases,the heat transfer coefficient of the channel surface shows a trend of first increasing and then decreasing,while the heat transfer coefficient of the smooth surface shows an increasing trend;When pulse spraying is used,not only the time to reach thermal balance can be shortened,but also the work quality can be greatly reduced.When the spray flow rate is 0.45 L/min and the thermal balance is reached 80.9%of working medium is saved in the working condition corresponding to the duty ratio of 0.4 compared with the continuous spray.