Finite time thermodynamics analysis of endoreversible ground source heat pump cycle

Abstract

Based on the theory of finite-time thermodynamics, a model of the reversible ground-source heat pump cycle accounting for heat transfer losses is established. Research shows that when the flow rate on the evaporator side and the condenser side is in the effective range 20-100 m3/h, the theoretical limit unit COP of the ground source heat pump under the refrigeration condition can reach the extreme value of 10.7, while the theoretical limit unit COP based on the reverse Carnot cycle is 20.1. The theoretical limit unit COP of the ground source heat pump under heating conditions can reach the extreme value of 9.8, while the theoretical limit unit COP based on the reverse Carnot cycle is 12.9. Under the refrigeration condition, in order to improve the unit COP, the flow rate on the evaporator side can be properly reduced, and the flow rate on the condenser side can be increased. Under the heating condition, in order to improve the unit COP, the flow rate on the condenser side can be properly reduced, and the flow on the evaporator side can be increased. The unit COP improves by 11.3% after optimization during the cooling season compared with the benchmark COP. The unit COP improves by 5.4% during the heating season after optimization, compared with the baseline.