Optimal phase change temperature for building cooling heating and power system with PCM-TES based on energy storage effectiveness

Abstract

Integrating thermal energy storage (TES) equipment with building cooling heating and power (BCHP) system can improve system thermal performance. In this paper, a simplified model of TES-BCHP system composed of a gas turbine, an absorption chiller and TES equipment with PCM is presented. To evaluate the energy saving effect of PCM-TES, a new index, energy storage effectiveness, is proposed and its relationship with primary energy consumption is established. Aimed at maximizing the energy storage effectiveness, the optimal phase change temperature of the PCM-TES-BCHP system is obtained. The results show that the theoretically optimal phase change temperature is just the geometrical average value of ambient temperature and exhaust gas temperature from gas turbine for ideal PCM-TES equipment with infinite number of transfer units. It also indicates that both energy storage effectiveness and optimal phase change temperature in-crease with increasing number of transfer units. So improving the thermal performance of PCM-TES device is favorable for increasing energy efficiency and saving primary energy consumption accordingly. This work is of great importance in guiding the optimization design of practical phase change temperature of the PCM-TES-BCHP systems.