Analysis of Two-Phase Flow in the Capillary Wick Structure of Flat Heat Pipe with Different Orientation

Abstract

This paper addresses simulation of phase change mechanism in the capillary wick of a flat heat pipe. The two-phase flow through porous media has wide application especially in heat pipes. It is a thermodynamic device that transports heat energy from one location to another with a negligible temperature drop. The present analysis concentrates only on the two-phase zone of the porous wick structure. The basic governing equations used for the formulation are continuity, mixture momentum, liquid conservation and energy. These equations are converted into ordinary differential equations using similarity transformation and two-phase similarity solutions are obtained for both boiling and condensing flows. The adjacent layer to the wall is considered to have two-phase region where the liquid and vapour can coexist. The liquid wall saturation, non-dimensional temperature and non-dimensional temperature gradient are predicted numerically during the phase change of water-steam system in the heat pipe for horizontal and vertical cases.