超疏水表面膜态池沸腾传热实验研究

An Experimental Study of Pool Film Boiling Heat Transfer on Superhydrophobic Surfaces

通过纳米颗粒沉积法在不锈钢球上制备了静态接触角大于160°的超疏水表面,并采用淬火法对该不锈钢球在过冷度为0℃~25℃的去离子水中的瞬态池沸腾传热过程进行了实验研究。结果表明,由于表面的超疏水特性,整个瞬态沸腾过程直至极低表面过热度时始终处于膜态沸腾状态。不锈钢球的冷却速率随着过冷度的增大而提高,其膜态沸腾的热流密度和平均努塞尔数也随着过冷度的增加而近似呈线性增长的趋势。对汽膜演化过程的可视化观察发现,在过冷度较大时蒸汽产生量减少,导致汽膜层扰动减弱、汽液相界面趋于平稳。

Superhydrophobic surfaces with a static contact angle greater than 160° were prepared on stainless steel spheres using the nanoparticle deposition method.The transient pool boiling heat transfer of water on the modified spheres was investigated experimentally via the quenching technique for the subcooling degree varying from 0℃ to 25℃.It was shown that the entire course of the transient boiling processes is within the film boiling regime until a very low wall superheat due to the superhydrophobicity of the surfaces.As the subcooling degree is increased,the cooling rate of the spheres speeds up and the film boiling heat flux and average Nusselt number increase almost linearly.Based on the visualized observation on the evolution of the vapor film,it was also found that the vapor generation rate decreases upon increase of the subcooling degree,leading to deteriorated disturbance within the vapor film and stabilized vapor-liquid interface.