Paper No 1072 – Numerical evaluation of high-temperature heat pump and thermal energy storage system for industrial processes – 14th IEA Heat Pump Conference, Chicago, USA
A numerical investigation was conducted on a high-temperature heat pump (HTHP) that can supply heat at 200°C and two types of thermal energy storage (TES) systems. The HTHP cycle employs a multistage water vapor compression process to achieve a high-temperature lift. Concrete was used as the sensible heat storage (SHS) system, while strontium bromide/water (SrBr2/H2O) was used as the working pair for the thermochemical energy storage (TCES) system. The multistage HTHP cycle was first analyzed based on an enthalpy balance with specific temperature conditions, and then the performance of both the SHS and TCES systems connected to the HTHP cycle was estimated. The HTHP cycle achieved a COP of 4.41 with an evaporation temperature of 90°C and a condensation temperature of 160°C. During storage, 500 kW of heat was supplied at 200 °C for 8 hours. The TCES system required 45% and 68% less mass and volumetric size, respectively, in storage mode. During discharge operation, the TCES system was able to supply heat at a temperature of over 200°C under all conditions, while the SHS system had a maximum cycle out temperature of 180°C. The TCES system also had a heat output rate of ~500 kW and round-trip efficiency (RTE) of 0.82.