Integrated High-Temperature Heat Pump and Thermal Energy Storage Laboratory Rig – Development of the validation plant and preliminary commissioning results
This work presents the design and preliminary commissioning results of an integrated heat upgrade system using a Stirling Cycle heat pump with two thermal energy storage units for industrial heat generation. Heat is upgraded to 200-250°C by the Stirling heat pump using a low temperature water vector as source. The heated stream is used for steam production, and for charging a thermal energy storage unit, which can also be discharged to continue with the steam production when it is too expensive to operate the heat pump due to higher electricity prices. The validation plant has two closed circuits filled with pressurized water, working as the heat transfer fluid. Both circuits are connected to the high-temperature heat pump. Additionally, two latent heat thermal energy storage units have been installed to increase the flexibility and overall performance of the system. One on the cold circuit, featuring a phase change material with a melting temperature of 75°C, enabling it to store waste heat when the heat pump is not operating. And the second, on the hot circuit, featuring a phase change material with a melting temperature of 227°C. Supporting equipment includes circulating water pumps, pressure vessels, electric heaters, control valves, temperature and pressure sensors, and the steam generator. The validation plant is designed to deliver about 200 kW of heat to the steam generator.