喷雾冷却沸腾传热强化试验

随喷雾流量及过热度增加,热流密度增大,但热表面中心干涸区变大、液膜覆盖区减小,表面利用率降低,传热性能有提升空间。基于此,通过改变单喷嘴高度、设计微孔阵列喷嘴两种途径,探讨热表面液膜均匀性和喷雾冲击强度对传热的影响规律。结果表明单喷嘴高度存在最佳值(4 mm),此时热表面无干涸区,喷雾冷却沸腾传热性能最强;与喷嘴高度6 mm相比,在喷雾流量为50 mL/min、过热度为20 K时,热流密度提高了13%;微孔阵列喷嘴形成的液膜分布更均匀,使得表面温度也较均匀,当过热度大于10 K,微孔阵列喷雾传热性能更优,比上述工况下单喷嘴的热流密度提高16%。强烈冲击的均匀薄液膜是决定喷雾冷却沸腾传热的关键,为进一步强化喷雾冷却沸腾传热提供了可行的方向。

Spray cooling boiling heat transfer enhancement test

The heat flux increased with the increase of spray flow and superheat,but the dry area in the center of the thermal surface became larger,the liquid film covering area and the surface utilization rate decreased,therefore,the heat transfer performance had room for improvement.Based on this,the influence of liquid film uniformity and spray impact intensity on heat transfer was investigated by changing the height of single nozzle and designing micro-hole array nozzle.The results show that the height of a single nozzle has an optimal value(4 mm),there was no dry area on the thermal surface at this time.Compared with the nozzle height of 6 mm,when the spray flow was 50 mL/min and the superheat was 20 K,the heat flux increased by 13%.The liquid film formed by micro-hole array nozzle was more evenly distributed,which made the surface temperature more uniform.When the superheat was higher than 10 K,the heat transfer performance of the micro-hole array spray was better,and the heat flux is 16%higher than that of the single nozzle under the same condition.The uniform thin liquid film with strong impact was the key of spray cooling boiling heat transfer,which provides a feasible direction for further strengthening the spray cooling boiling heat transfer.