A single stage phase change latent thermal storage exchange system which is useful for an ambient temperature range was experimentally investigated to develop a more complex multi phase system, and verify the validity as an energy saving system. We focused on lauric acid which is one of fatty acids as a thermal storage medium. The lauric acid is one of phase change latent heat storage materials which are harmless to the human body. The heat transport mechanisms which accompany a melting process and a solidification process were analyzed using an appropriate visualization.