关键词: 润湿性, 微纳结构, 池沸腾, 超亲水, 超疏水

Abstract: Experiments were conducted to study the effect of super hydrophilic/hydrophobic surface on the pool boiling heat transfer. The superhydrophilic surface was prepared by H₂O₂ oxidation and the superhydrophobic surface was prepared by ammonia immersion and high molecular material modification. In the experiments a high speed camera was used to record the process of bubble growth,using water as the working fluid at atmosphere pressure. It is found that for superhydrophobic surface the bubbles were easy to generate and not easy to detach at the onset of nucleate boiling accompanied by good heat transfer performance and low surface superheat. The surface superheat was only 2.4K. With the increase of heat flux,the bubbles were easy to merge and form large ones,which block the heat transfer and make surface have low critical heat flux(CHF). However,for superhydrophilic surface the existence of micro-nano sheet structure increased the surface roughness,it not only increased heat transfer area and the number of nucleate sites,but also made surface have superhydrophilic characteristic. So the bubble departure frequency was large and the boiling heat transfer was enhanced greatly. The maximum heat transfer coefficient was nearly 1.7 times than that of plain surface and the CHF can be improved to 131.0W/cm²,which showed better heat transfer performance in pool boiling.

Key words: wettability, micro-nano structure, pool boiling, superhydrophilic, superhydrophobic