Heat transferential study on a heat storage container with phase change material

Abstract

This paper presents heat transfer characteristics of a heat storage container utilizing latent heat storage material, calcium chloride hexahydrate (melting point 28°C). The heat storage container is consisted of a vertical cylindrical pipe with a vertical heat transfer tube at the center and the latent heat storage material containing into the cylindrical pipe. The heat release and heat transfer characteristics during the solidification of the latent heat storage material are experimentally studied. The following results are obtained. The relation between the time and total heat flow rate, that is, the heat release characteristics have the following three stages: (1) the stage of sensible heat release from liquid heat storage material, (2) the latent heat release stage, (3) the stage of sensible heat release from solid heat storage material. The actually measured values of thermal resistance show a tendency similar to that of the theoretical values, but their absolute values are smaller than those of theoretical values by about 40%. This is because the solidified crystals of heat storage material do not grow in circular shape concentric with the heat transfer pipe but grow in dendritical shape, and dendritical crystallized portions function as fins.