Design Optimization and Performance Analysis of Electro-Thermal Molten Salt Heat Storage Combined Heat and Power Systems

This study focuses on the configuration optimization of electro-thermal molten salt heat storage combined heat and power (CHP) systems. A flexible CHP system architecture integrating a synchronous self-shifting (SSS) clutch is proposed. Furthermore, the configurations and matching parameters of both subcritical and supercritical CHP systems utilizing molten salts in different temperature ranges are optimized. The energy consumption characteristics and techno-economic performance of various operation modes are analyzed in detail. Multi-parameter optimization is conducted with the objective of maximizing electro-exergy efficiency for a CHP system featuring a rated electric load of 300 MW and a rated thermal load of 500 GJ·h^-1. Optimization results indicate that the supercritical system employing molten salt with an applicable temperature range of 397 °C to 670 °C exhibits the best thermal performance, achieving an electro-exergy efficiency of 50.36%. The optimized system configuration comprises five high-pressure feedwater heaters (FWHs) and four low-pressure FWHs, with a feedwater temperature of 331 °C. Energy performance analysis reveals that, in the optimal thermal performance system, the exergy efficiencies of the power generation subsystem under 100% and 15% turbine heat acceptance (THA) condensing conditions, extraction heating, and back-pressure heating modes reach 84.23%, 84.31%, 86.65%, and 92.18%, respectively.