Analysis of collector-storage building walls using phase-change materials

The use of thermal storage walls that serve both as solar collector and thermal storage is well known. The wall is usually composed of masonry or containers filled with water to provide sensible heat storage, i.e., storage resulting from the specific heat capacity of a material as it increases in temperature. An interesting alternative to the standard materials are phase-change materials (PCMs) which employ latent heat storage. Latent heat storage utilizes the energy associated with a change of state of a material such as the transition from a solid-to-liquid, or liquid-to-gas. The solid-to-liquid phase change is preferred for many applications because of the much smaller volume change resulting in this transition for a given amount of energy storage. This paper summarizes the results of a simulation study of the use of PCMs as a collector-storage wall.