Comparative Study of Heat Storage System in Water Vapor Compression Heat Pump for Industrial Processes

Abstract

The thermodynamic performances of a two-stage high-temperature heat pump (HTHP), utilizing water/steam as a refrigerant, along with two distinct thermal energy storage systems, concrete sensible heat storage (SHS) and strontium bromide/water thermochemical energy storage (SrBr2/H2O TCES), were evaluated. The proposed HTHP demonstrated sufficient capability to supply heat above 200°C with a high COP, 5.2-7.5. While concrete SHS cannot release heat beyond the temperature at which it was stored, 190°C, TCES can release heat above 200°C. Additionally, the SHS system cannot satisfy the limited heat release operation time when it has lower cycle out temperature than the condensation temperature of the HTHP cycle. It was also observed that SrBr2/H2O TCES required 45% less material mass and 68% less volume, respectively. On the techno-economic evaluation, the integrated system comprising HTHP and TCES yielded a net present value of €454,075-€171,890. Furthermore, the internal rate of return was calculated to be between 15.3-23.0%.