Pool boiling heat transfer enhancement in binary mixtures by surfactant additives

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.