Performance analysis on combined energy supply system based on Carnot battery with packed-bed thermal energy storage

Pumped-thermal electricity storage (PTES) is a promising energy storage technology with high-efficiency, energy density, and versatility of installation conditions. In this study, a 20 kW/5 h phase change packed-bed thermal energy storage experimental system is established and employed to validate the accuracy of thermal energy storage (TES) component within the broader PTES system. Moreover, a novel combined system based on latent TES is proposed, incorporating Joule-Brayton and organic Rankine cycle-based subsystems for supplying cold, heat, electricity, and hydrogen. Operational strategies are also explored to optimize the multifunctional capabilities of the system. The thermal energy density of the system, when phase change materials (PCMs) are used instead of sensible heat storage materials, can be improved from 167.85 kWh/m3 to 272.58 kWh/m3. Proton exchange membrane electrolyzer cycle (PEMEC) is coupled into the Carnot battery system, and a comprehensive analysis of the system's performance is conducted. With the charging time of 5 h, the energy performance of the multi-generation system (EPMG) can be reached up to 143 % and 146 % in combined cooling, heating, and power (CCHP) and multi-generation energy system (MGES) modes, respectively. The MGES mode is made 3.44 % more exergy efficient than the CCHP mode as a result of the ingenious coupling of the hydrogen production process with the power generation process and heating/cooling processes. The system in one charging/discharging process has the capability to generate 240.86 kg of hydrogen, 34.82 MWh of heat, 12.97 MWh of cold, and 40.90 MWh of electricity.