全氟烷基表面活性剂强化池沸腾换热

针对不同浓度的全氟烷基碘化物（Le-134）水溶液进行了核态池沸腾换热实验研究。首先对Le-134的界面吸附特性及在紫铜表面的润湿性进行了研究。结果表明，其静态表面张力随浓度增大而减小，动态表面张力下降速度随浓度增加而加快，在超过临界胶束浓度（critical micelle concentration，CMC）的较高浓度下（≥40mg/L），10s以内溶液表面张力即降低到20mN/m以下。Le-134水溶液在紫铜表面接触角随浓度增加而减小，在300mg/L时接触角仅为21°，具有良好的润湿性。沸腾过程与去离子水相比，Le-134水溶液产生的汽泡数量明显增多，汽泡尺寸减小，汽泡合并现象减少。结果表明，Le-134的添加可以有效强化池沸腾换热，同热流密度下随浓度增大强化效果越显著；同浓度下，随热流密度增大强化效果有所减弱。在10W/cm²下，300mg/L的Le-134相对去离子水工况强化效果最明显，沸腾表面过热度减少49.3%，沸腾换热系数增加109.1%。

Nucleate pool boiling heat transfer characteristics of perfluoroalkyl quaternary ammonium iodide

Saturated pool boiling heat transfer experiments for different concentrations of perfluoroalkyl iodide (Le-134) aqueous solution has been experimentally investigated. The interface adsorption characteristics of Le-134 and the wettability of copper surface were investigated firstly. The static surface tension decreased with increasing concentration, and the variation of dynamic surface tension reduction increased with increasing concentration. At the concentration exceeding CMC (≥40mg/L), the surface tension of the solution was reduced to less than 20mN/m within 10s. Le-134 solution had good wettability, and the contact angle of the aqueous solution on the surface of the copper decreased with increasing concentration, which was only 21° at 300mg/L. Compared with deionized water, the amount of bubbles produced by Le-134 aqueous solution in pool boiling was significantly increased besides the bubble size and the bubble coalescence was reduced. It can be demonstrated that the heat transfer enhancement was more effective with the increase of concentration at the same heat flux, while the heat transfer performance was weakened with the increase of heat flux at the same concentration. Compared to deionized water, the obvious enhancement was observed at 10W/cm² with 300mg/L Le-134. The superheat of the boiling surface was reduced by 49.3%, and the boiling heat transfer coefficient was increased by 109.1%.