Assessment of refrigerant mixtures performance with thermal glide for cold climate air-source heat pumps

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Heat pumps are currently considered as one of the most promising means for meeting low energy consumption requirements in buildings. However conventional air source heat pumps suffer from severe limitations in terms of performance at low ambient temperatures, while new designs such as multi-stage compression or ground source heat pumps are still very costly. The main challenge is to improve on the air-source heat pumps low efficiency in cold climates at a reasonable cost. The use of mixtures of refrigerants with the aim of increasing heat pumps performance (COP and/or heating capacity) by taking advantage of the thermal glide has been so far, little studied for the heating and cooling of buildings. In this paper, the goal is to assess the performance of refrigerant mixtures with thermal glide for cold climate air-source heat pumps. A simple theoretical and an extended model have been developed and used for refrigerant mixtures performance evaluation. It is shown that a good potential exists in refrigerant mixtures with moderate glide to improve the performance of cold climate air-source heat pumps.