*Article* **Novel Simulation Algorithm for Modeling the Hysteresis of Phase Change Materials**

#### **Anna Zastawna-Rumin 1, Tomasz Kisilewicz 1 and Umberto Berardi 2,\***


Received: 20 January 2020; Accepted: 3 March 2020; Published: 5 March 2020

**Abstract:** Latent heat thermal energy storage (LHTES) using phase change materials (PCM) is one of the most promising ways for thermal energy storage (TES), especially in lightweight buildings. However, accurate control of the phase transition of PCM is not easy to predict. For example, neglecting the hysteresis or the effect of the speed of phase change processes reduces the accuracy of simulations of TES. In this paper, the authors propose a new software module for EnergyPlus™ that aims to simulate the hysteresis of PCMs during the phase change. The new module is tested by comparing simulation results with experimental tests done in a climatic chamber. A strong consistency between experimental and simulation results was obtained, while a discrepancy error of less than 1% was obtained. Moreover, in real conditions, as a result of quick temperature changes, only a partial phase transformation of the material is often observed. The new model also allows the consideration of the case with partial phase changes of the PCM. Finally, the simulation algorithm presented in this article aims to represent a better way to model LHTES with PCM.

**Keywords:** phase change material; hysteresis; simulations; EnergyPlus; thermal energy storage
