Modeling horizontal storage tanks with encapsulated phase change materials for building performance simulation

The current article describes a model developed to simulate the performance of a horizontal storage tank filled with commercially available, slab-like, macro-encapsulated phase change material. The model is implemented as a component for the TRNSYS simulation program, and is intended for integration into whole building energy analysis. It is based on one-dimensional conduction and uses the thermo-physical properties of the phase change material to maps its thermal behavior, considering hysteresis in the enthalpy-temperature curve. The validity of the modeling assumptions is assessed using a detailed finite-element model and basic dimensional analysis. Experimentally measured thermal behavior of a full-scale phase change material storage unit is used to validate the model. A variety of flow rates, inlet temperature profiles and temperature intervals are evaluated in 13 distinct tests. Comparisons between measurements and simulations indicate the validated model can simulate the behavior of such phase change material storage tanks and be used to improve their design for specific applications.