Alternative mixtures to R-600a. Theoretical assessment and experimental energy evaluation of binary mixtures in a commercial cooler

Abstract

This work focuses on the exploration of binary mixtures as alternative to isobutane (R-600a) from a theoretical and experimental point of view. To predict the most energy efficient blends, a theoretical model was used that analysed 5445 different blends consisting of 11 pure refrigerants. Three blends were selected for experimental testing in a commercial cabinet: R-1234ze(E)/R-600 (8/92)%mass, R-152a/R-600 (8/92)%mass and R-32/R-600 (2/98)%mass. The results of the 16-hour tests showed that, at their optimum refrigerant charge, the R-1234ze(E)/R-600 (8/92)%mass and R-152a/R-600 (8/92)%mass blends achieved energy consumption reductions of −2.69% and −5.04%, respectively, while the R-32/R-600 (2/98)%mass blend showed an increase of +0.36%. All blends reduced compressor consumption, but increased duty cycles. The results demonstrate the existence of alternative blends that can significantly reduce isobutane energy consumption with similar thermodynamic properties.