Improving cold climate air-source heat pump performance with refrigerant mixtures. (5th March 2015) - Hakkaki-Fard, Ali
Abstract: Heat pumps (HP) are one of the most adapted heating solutions for meeting low energy consumption requirements of buildings. However, improving the performance of the heat pumps at low ambient temperatures is still an open challenge. This paper assesses the potential benefits of implementing zeotropic refrigerant mixtures in residential air-source heat pumps for cold climates, in order to increase their seasonal performance. The seasonal performance of a heating system with an air-source heat pump, supplemented with an auxiliary electric heater is studied in two cold climate cities of Montreal and Edmonton. To this aim, a detailed screening heat pump model previously developed is modified and used. Furthermore, the performance of the system with a variable composition refrigerant mixture is assessed, the main goal being to illustrate the possibility of applying environmentally friendly zeotropic refrigerant mixtures in conventional heat pumps, with minimal changes in the components, in order to improve their performance in cold climate conditions. Highlights: Refrigerant mixtures performance in air-source heat pumps is assessed. A hybrid heating system of air-source heat pump and electric heater is numerically simulated. Performance of R32-CO2 mixture, both for a constant composition of 80/20 and for a variable composition is assessed. Seasonal energy consumption of the system can be reduced by up to 12% with R32-CO2 (80/20) refrigerant mixture. Seasonal energy consumption can be reduced by up to 23% with R32-CO2 variable mixture composition.