过冷池沸腾中气泡聚并对壁面换热影响的实验研究  

Effect of bubble coalescence on the wall heat transfer during subcooled pool boiling

作　　者：Abdoulaye Coulibaly 林曦鹏[1] 毕景良[1] 柯道友[1] 

机构地区：[1]清华大学热科学与动力工程教育部重点实验室,北京100084

出　　处：《清华大学学报（自然科学版）》2014年第2期240-246,共7页Journal of Tsinghua University(Science and Technology)

基　　金：国家"九七三"重点基础研究项目(2011CB706904)

摘　　要：该文实验研究了气泡聚并对核态池沸腾换热的影响。在恒壁温的边界条件下,利用微加热器阵列加热液态FC-72产生气泡,同时利用高速数据采集系统测量特定区域的热流密度。由于气泡之间液体层的蒸发和气泡聚并后产生的振荡,沸腾过程中发生气泡聚并时热流密度的波动远强于加热表面仅有单气泡生成时的情形。与单气泡成核相比,气泡聚并所产生的振荡提高了加热表面的再润湿频率,从而显著增加了平均传热。观测还表明,由于气泡之间的液体层被仍处于惯性生长阶段的气泡推离,气泡聚并速度非常快时并不会伴随热流量的增加。实验结果表明:当无量纲的聚并数Ncoal>0.2时,气泡聚并能够增强换热;反之,当Ncoal<0.2时,气泡聚并则会减弱换热。This study experimentally investigated the effects of bubble coalescence on nucleate pool boiling. A micro heater array was used to generate vapor bubbles in FC-72 liquid with constant surface temperature boundary conditions while the heat flux at selected locations was measured using a high speed data acquisition system. The heat flux for boiling with coalescence was found to fluctuate much more than when only a single bubble formed on the surface due to the vaporization of the liquid layer trapped between the bubbles and oscillation of the bubbles after coalescence. These oscillations significantly increased the average heat transfer by increasing the frequency of rewetting of the heated surfaces compared to single bubble nucleation. The observations also showed that very fast coalescence events were not accompanied by an increase in the heat transfer rate as the liquid layer between the bubbles was physically pushed away by the rapid bubble growth during the inertial bubble growth stage instead of evaporating. The results show that the heat transfer increases for the dimensionless coalescence number, Ncoal, more than 0.2 but decreases {or Nc,,d less than 0.2.

关 键 词：微加热器阵列 气泡动力学 气泡聚并 热传递 池沸腾 

分 类 号：TK124[动力工程及工程热物理—工程热物理]