Theoretical performance comparison for a regenerator-enhanced three-stage auto-cascade refrigeration system using different zeotropic mixed refrigerants

•A novel three-stage RACR was proposed to improve the performance of ACR.•The R134a/R23/R14 RACR system performed better than the ACR system.•The influence of the refrigerant ratio on RACR performance was investigated.•Different hydrocarbons were provided as alternatives to R134a and R23.•R600/R170/R14 performed the optimum performance in the RACR system.