Preliminary analysis and optimization of a thermoelectrical system based on the supercritical CO₂ cycle

A novel type of thermoelectric energy storage (TEES) utilizing supercritical carbon dioxide (S-CO₂) cycle and storage of heat in hot water is presented. It is based on the conversion of electricity into thermal energy during charge by a compressor and on the conversion of thermal energy into electricity during discharge by a turbine. In this paper, the background and a short review on TEES and S-CO₂ cycle is given firstly. Following the introduction as a general concept, the S-CO₂based system is presented by briefly providing a description of the thermodynamic cycle and the corresponding operating conditions. Then a thermodynamic analysis is completed to obtain the relationships between the key parameters and performance of the system under design conditions after the computational models have been built. Next multiple parameters that have the most significant effect on the system performance are chosen for subsequent parameter optimization based on the calculation models. The system performance and economic cost have been optimized by multiobjective optimization, and the Pareto solution set is finally provided. The paper is concluded by discussing the engineering prospects of this system mainly dependent on technology improvements of the heat storage materials and the core equipment such as the compressor, turbine, and the heat exchanger.