Combined cooling, heating, and power generation performance of pumped thermal electricity storage system based on Brayton cycle

Pumped thermal electricity storage (PTES) is considered as a promising mechanical energy storage technology owing to the advantages of high energy density, high efficiency, and no geographical restrictions. PTES system has great potential as a primary mover of the combined cooling, heating, and power (CCHP) system since energy is stored in the form of heat and cold energy which can be effectively delivered and converted to electricity. In this study, a novel CCHP system based on Brayton-based PTES system is proposed. An unsteady model was established to simulate the system and explore its potential of energy storage and delivery. The characteristics of system operating under different modes have been explored to obtain a complete map of system coefficient of performance (COP) under the cyclic stable states. Performance of the system is evaluated for energy requirements of an office building located in Norway. The obtained results showed that the COPs of the electrical storage, combined heating and power, and CCHP modes achieved 63.5%, 137.9%, and 188.1%, respectively, and the exergetic efficiency increased by 1.4% compared with the situation of electricity storage. Proper active heat and cold delivery from hot and cold reservoirs can improve the electrical efficiency and discharge stability. This system is therefore very worthy of being practical applied and popularized.