Enhancement of pool boiling heat transfer in water and ethanol/water mixtures (effect of surface-active agent)

Abstract

The surface tension of alcohol/water mixtures has been measured over the whole fraction range and then it has been measured when a surface-active agent was added into the mixtures. The effect of the concentration of alcohol and the surface- active agent on surface tension was experimentally clarified, in order to gain base data related to enhancement of the heat transfer coefficient in the mixtures and water. The experiment was also carried out to enhance the boiling heat transfer coefficients of water and alcohol/water mixtures on a horizontal heated fine wire at a pressure of 0.1 MPa by adding a surface-active agent into the tested liquid. The results show, the coefficients were enhanced in lower alcohol concentration (C ≦ 0.5) and low heat flux range which occur just after the onset of boiling. It was also found that the enhancement effect by the surfactant disappears in concentrations over 1000 ppm. Finally, we demonstrated that the surface tension remarkably affects the heat transfer coefficients in nucleate pool boiling. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(4): 229–244, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20010