Effects of the heating surface structure of phase change chamber on boiling-condensation coexisting phase change heat transfer

Abstract The influences of the heating surface structure of phase change chamber on heat transfer characteristics are studied by using smooth, equal-width and variable cross-sectional area grooved heating surfaces, and visualization is made of the boiling-condensation coexisting phase change phenomena inside the chamber. The experimental results confirm that there is an optimum working fluid filling ratio for the phase change chamber to acquire its best performance. The optimum filling ratio for the smooth and equal-width grooved heating surface phase change chamber is found to be 36.0% and 11.4%, respectively. The experimental results also disclose that the equal-width grooved heating surface has the best performance and the overall heat transfer coefficient of the phase change chamber is augmented by more than 44% over the smooth heating surface. Although the thermal resistance of condensation is the dominant of the overall heat transfer resistance, it is proved that enhancing boiling is still an efficient way due to the strong interactions between the boiling and condensation processes inside the phase change chamber.