Air-source hybrid absorption-compression heat pumps with three-stage thermal coupling configuration for temperature lift over 150 °C

Abstract

Heat pump technology is promising for low-carbon heating supply. However, temperature lift of current technology is still insufficient to meet different industrial demands. Aiming at larger temperature lift, this paper extends the thermal coupling of absorption heat transformer (AHT) and vapor compression heat pump (VCHP) from two-stage configuration to three-stage configuration. Two different three-stage air-source hybrid absorption-compression heat pump cycles are proposed, and analyzed together with a modified two-stage one. Performance optimization, parameter analysis and second law analysis are carried out for the three hybrid heat pump cycles. The three-stage cycle coupling single-stage AHT with double-stage VCHP achieves the best COP of 2.10–1.32 under the temperature lift of 70.0–151.0 °C, while the two-stage one can only achieve COP of 1.10 and temperature lift of 129.0 °C. This enhanced performance is attributed to the less irreversible loss in throttling process. With both better performance and larger temperature lift, the proposed cycle is promising for the industrial application of air-source heat pump.