Decarbonization performances of a transcritical CO2 heat pump for building heating: A case study

Abstract

An experimental transcritical CO2 heat pump system was implemented in the severely cold region, Harbin (China), and the energy and exergy performances as affected by the expansion valve opening were compared and the environmental and economic performances of CB (Coal-fired Boiler), GB (Gas-fired Boiler), EB (Electric Boiler), and HP (Heat Pump) were analyzed. The results showed that the system COP decreased by around 0.2 when the expansion valve opening was increased from 60% to 80% with the highest system COP of 2.40. The system exergy destruction and exergy efficiency increased from 5.12 and 33% to 5.61 kW and 37% when an increase in the expansion valve opening from 60% to 80%, respectively. The CO2 and pollutants emissions of HP were 52% ∼ 92% lower than CB and EB. The life-cycle cost of HP for a 15-year working period was the lowest (36.57 × 104 CNY) and it was 84%, 77%, and 39% of CB, GB, and EB, respectively. The results revealed that the transcritical CO2 heat pump system has better environmental and economic performances than CB, GB, and EB, its emissions were 52% lower than CB and EB and its life-cycle cost was only 39% of EB.