本文通过选用不同类型表面活性剂-SDS和Triton X-100,系统研究了表面活性剂对于乙醇-水混合工质的强化沸腾换热规律。实验结果表明,表面活性剂能够一定程度起到强化沸腾换热的作用,可以有效地减少使用双组分混合工质引起的换热性能下降。但随着乙醇浓度的增加,这种影响作用逐渐降低。可视化观察发现,加入表面活性剂前后沸腾现象之间存在着明显的差别,主要表观为汽泡脱离直径减小,脱离频率增加,汽泡相互间的合并减弱等。
Heat transfer coefficients were measured for pool boiling of ethanol/water binary mixtures with and without surfactant additives on a plate heater at 0.1 MPa. The experiment was carried out in the whole range of the ethanol fraction and in a wide range of concentration of surfactants for two surfactants of SDS (anionic surfactant) and Triton X-100(nonionic surfactant). The results show that the heat transfer coefficient was enhanced considerably by these two surfactants in the low ethanol fraction range. However, the effect of the surfactants on the boiling heat transfer became small with an increase in both heat flux and the ethanol fraction. The photographic and visual observations of binary mixtures with surfactants boiling behavior indicate marked difference from that of mixtures: bubble department diameter becomes small, and bubbles depart at much higher frequencies and the coalescence between two neighboring bubbles is minimal.