喷雾冷却高热流密度散热传热特性研究

Heat Transfer Characteristics of Spray Cooling with High Heat Flux Dissipation

针对喷雾冷却的高热流散热方式,设计和构建封闭循环实验装置。通过热电偶计算得到发热面的热流密度。通过激光多普勒测速仪(PDA)测量喷嘴的液雾分布、粒径和尺寸。基于气泡动力学与传热学,建立喷雾冷传热特性的理论模型。数值模拟的计算结果显示出喷雾高度对喷雾冷却曲线的影响:随着喷雾高度的增大,喷雾冷却的换热能力升高,与实验结果的变化趋势相同。同样采用数值的方法,给出不同喷雾张角、不同喷雾压力和不同喷雾高度下的换热系数,对喷雾冷却的传热特性进行分析。研究表明,两相区内的喷雾冷却换热能力得到了显著的增强,喷雾冷却存在最佳喷雾高度。

A closed loop experimental device of spray cooling is designed and constructed based on high heat flux dissipation.Hot surface heat flux is calculated by thermocouple;spray distribution of nozzle and grain diameter and size are measured by PDA.A mathematical model of spray cooling is presented based on bubble dynamics and heat transfer.The results of numerical simulation show the relationship between the spray height and the spray cooling curve.With the spray height increasing,the spray cooling heat transfer capacity is enhanced,consisting with the same trend by experiment.The heat transfer coefficients in different spray angle,pressure,and height are presented,and the spray cooling heat transfer characteristics are analyzed.The conclusion is that the spray cooling heat transfer capacity in two phase region is significantly enhanced,and spray cooling has an optimal spray height.