超亲水表面在淬火冷却过程中的沸腾传热特性

Boiling heat transfer characteristics during quench cooling on superhydrophilic surface

为了研究超亲水表面对于沸腾传热的强化效果,将氧化硅纳米颗粒沉积在不锈钢球表面上制备一种静态接触角接近于0°的超亲水表面,利用瞬态淬火的方法研究该表面在淬火冷却过程中的沸腾传热特性.实验结果表明,超亲水表面有效提高了淬火速率,冷却时间较原始表面缩短了56.5%.该表面显著提高了临界热流密度及其所对应的表面过热度,较之原始表面分别提高了72.8%和23.3%.超亲水表面润湿性能的改善和汽化核心数的增加对过渡沸腾阶段的传热机理产生了重要影响,可以显著地观察到过渡-膜态沸腾和过渡-核态沸腾2个不同的阶段.

Superhydrophilic surfaces with a static contact angle of nearly 0°were prepared by depositing SiO2 nanoparticles on stainless steel spheres in order to study the enhancement effect of superhydrophilic surface on pool boiling heat transfer.The boiling heat transfer characteristics during quench cooling on such superhydrophilic surfaces were investigated via the transient quchching method.The experimental results showed that the quenching rate was improved remarkably with the cool-down time duration being shortened by 56.5%as compared to the original surfaces.The critical heat flux and its corresponding wall superheat were both increased in the presence of the superhydrophilic surfaces,and the relative enhancements were 72.8% and 23.3%,respectively.Due to the improvement in wettability and the increased availability of nucleation sites,the heat transfer mechanisms in transition boiling regime were found to be significantly modified by the superhydrophilic surfaces.Two distinct sub-regimes were clearly identified as the transition-film boiling and transition-nucleation boiling regimes.