Design and Performance of Thermal Energy Storage Module using High Thermal Conductivity Phase Change Composite Material

HVAC (Heating, Ventilation and Cooling) accounts for approximately 15-30% of a commercial building’s electricity cost and about 20-40% of electricity consumption. Electricity costs charged by the utilities companies for commercial building customers includes consumption charges ($/kWh) and demand charges ($/kW) depending on the time of use (TOU) charges. Thus, there is great interest to reduce the electricity consumption charges and demand charges by using new energy efficient technologies and products. One such product is a thermal energy storage (TES) system using a phase change material (PCM) to offset the cooling costs associated with air-conditioning systems by reducing the electricity consumption during peak time periods. A patented phase change composite (PCC) TES material was developed that has high thermal conductivity and adjustable phase change temperature. Compared to ice, the PCC TES system is capable of higher heat transfer rate and has lower system and operational costs. Proof of concept demonstration and working prototype results of a PCC TES system were successfully completed. Results show that a PCC TES system can be designed for a commercial building and maintain high efficiency with either low or high discharge rates. Techno-economic analysis for peak shaving or peak load shifting of a commercial air-conditioning system was studied, comparing Ice and PCC TES system. Results show that a PCC TES system can compete with Ice TES system with favorable ROI (return on investment).