Numerical models of heat storage with respect to phase change materials considering hysteresis

Phase change materials (PCMs) absorb and release thermal energy that corresponds to the latent heat absorbed and released during phase changes. Thus, by efficiently utilizing solar heat, they are expected to stabilize the room temperature, resulting in reduced heating loads. The accurate prediction of the energy-saving effect of PCM utilization is important for designing buildings, and it is essential to adequately evaluate the influence of the hysteresis phenomenon, which occurs when the heating and cooling cycles of PCMs are repeated. This study examines the precise calculation modeling of PCMs that demonstrate complex hysteresis behaviors to accurately predict the PCM effect. The proposed approach includes a simple model with two temperature–enthalpy curves, a complex model with multiple curves, and a subcooling model. The accuracy of the proposed model is verified by comparison with the measurement results, and the models can be integrated into a heat load calculation program.