Particularly, the low GWP natural refrigerants, e.g. CO2, HCs, ammonia, etc., and HFOs are excluded mainly due to safety and cost reasons. Some of them belong to the A3 or B3 ASHRAE safety group, i.e. high inflammable and harmful fluids, while others are still too expensive because of their cost (see Fig. 3) and the required system redesign actions. Further research on such fluids is strongly encouraged to overcome these weaknesses reaching stable long term solutions on refrigerant environmental sustainability.
3. Experimental campaign
The experimental analysis is focused on the assessment of the coefficient of performance (COP) and the cooling capacity of HFC R407f and R410a identified as alternatives to the HFC R404a (benchmark). The laboratory system used for the experimental tests is now described before presenting the key outcomes. 3.1. Thermostatic chamber and control system