Multi-criteria (thermodynamic, economic and environmental) analysis of possible design options for residential heating split systems working with low GWP refrigerants

An analysis of design configurations is proposed for a 5 kW residential space heating split system comparing several low GWP refrigerants (R32, R290, R1234yf, R1234ze, XL41, XL55) as potential alternatives to the most common refrigerants actually used (R410A, R407C, R134a). By means of an ad-hoc model, the system performance has been estimated for several geometrical configurations among those possible according to the current compressor and heat exchangers technology. The configurations complying with geometric and thermodynamic constraints are discussed in terms of opposing criteria: economic (set-up and total costs), thermodynamic (COP) and environmental ones (LCCP). With R32 it is possible to define design configurations that are able to reach the best energetic performances for fixed set-up costs. In the range of low set-up costs solutions, R32 and R410A design options are able to work with the same performance. Particularly, R32 can reach the minimum LCCP value as propane with 15% lower total costs.