Alternative working fluids based onHFC-236fa

Alternative refrigerant mixtures were selected with a view to finding replacements for CFC-114 in high temperature heat pumps. The selection is carried out starting from the following mixtures: HFC-236fa + HFC-134a, HFC-143a, HFC-32, HFC-125, HE-170, HC-600a, HC-290. Both binary and ternary mixtures in the whole range of mass fractions were taken into account. Cycle calculations were done to find the best mixtures from the point of view of a maximum achievable COP and heating capacity. Thermodynamic properties of mixtures were calculated by means of the Carnahan- Starling-De Santis (CSD) equation of state. Vapor-liquid equilibria measurements were taken to increase the availability of experimental data on binary interaction parameter. Two mixtures were selected as replacement of HFC-114 in heat pump applications, i.e. HFC-134a / HFC-236fa (60/40) and HFC-32 / 236fa (15/85). Experimental tests were performed to compare the actual performance of the two selected mixtures with the performance of CFC-114 in high temperature heat pumps.