Exergy and energy analysis of three stage auto refrigerating cascade system using Zeotropic mixture for sustainable development

•Zeotropic mixture of R290/R23/R14 works with 22.6% increased exergic efficiency.•Zeotropic mixture of mass fraction 0.218:0.346:0.436 offers COP of 0.253.•Since emphasis on COP, evaporating temperature 0.253 COP became the only alternate.•This is the only alternate refrigerant mixture for three stage ARC system at −97 °C.

The Zeotropic mixture of environment friendly refrigerants (HC’s and HFC’s) being the only alternatives for working fluid in low temperature refrigeration system and hence three stage auto refrigerating cascade (ARC) system was studied for the existence using two combinations of (R290/R23/R14, R1270/R170/R14) three component Zeotropic mixture of five different refrigerants. The exergy analysis confirmed the existence of three stage ARC system. The performances of the system like Coefficient of Performance (COP), exergy lost, exergic efficiency, efficiency defect and the evaporating temperature achieved were investigated for different mass fractions in order to verify the effect of mass fraction on them. In accordance with the environmental issues and the process of sustainable development, the three component Zeotropic mixture of R290/R23/R14 with the mass fraction of 0.218:0.346:0.436 was performing better and hence can be suggested as an alternative refrigerant for three stage ARC system operating at very low evaporating temperature in the range of 176 K (−97 °C) at COP of 0.253 with 58.5% exergic efficiency (comparatively 22.6% increased value).