Modelling of an Active PCM Thermal Energy Storage for Control Applications

Abstract

This paper presents the results of an experimental and numerical study focusing on the control-oriented modelling of an actively charged/discharged phase-change material (PCM) thermal energy storage (TES) system. The PCM-TES system consists of five layers of commercial macro-encapsulated PCM panels with an air cavity in its center. Air can flow through the cavity to charge/discharge the PCM panels. The PCM-TES was tested in an environmental chamber and its dynamic response was carefully monitored. A detailed fifth order thermal network finite difference model for the system is developed and verified against experimental results. The detailed model is then simplified to a 2nd order model for control purposes. A five-parameter equation is developed to model the storage of heat in the PCM. An average and maximum temperature difference of 0.8 °C and 2.0 °C, respectively, is achieved between the experiment data and that simulated by the detailed model. The second order model has an average and maximum temperature difference of 0.2 °C and 0.9 °C, respectively, compared to the detailed model. It is thus adequate for real time model predictive control of the system.