Abstract
In this research, the investigation on the characteristics of the unsteady state phenomenon of the direct contact melting at the initial stage was carried out analytically, where the system starts to form a liquid film between the solid surface and the heating plate. Three types of heating conditions were examined. One was to have a constant heat flux at the top surface of the heating plate, the next was to have the constant heat flux at bottom surface of the heating plate, and the last was to have the constant heat transfer coefficient at the bottom surface of the heating plate. The difference in phenomena under three conditions were pointed out. Furthermore, various parameters such as the size of the heating plate, the thermal physical properties of the heating plate, the size and the thermal physical properties of the PCM, were varied for each condition, and the effect of each parameter was investigated. The results were summarized qualitatively at two points: one was the melting speed at the steady state, and the other was the time required to approach the steady state.