Thermodynamic analysis of a novel ejector-enhanced auto-cascade refrigeration cycle

Abstract This paper proposes a novel ejector-enhanced auto-cascade refrigeration cycle (NEARC). In the novel cycle, the ejector not only replaces an expansion valve to recover partial expansion work, but also greatly reduces the throttling loss of the other expansion valve connected to the evaporator. The energy and exergy analysis methods are used to evaluate and compare the performance of NEARC using R290/R170 with conventional auto-cascade refrigeration cycle (CARC) and previously proposed ejector-enhanced auto-cascade refrigeration cycle (EARC). The simulation results show that under all given working conditions, the COP and exergy efficiency of NEARC are superior to those of CARC, but not always superior to those of EARC. With the change of initial mass fraction of R290, the COP and exergy efficiency of the three cycles all have maximum values. The maximum COP and exergy efficiency of NEARC are 42.85% and 42.71% higher than those of CARC, and 18.10% and 17.99% higher than those of EARC, respectively. When initial mass fraction of R290 is about 0.5, CARC and EARC have the best performance, and NEARC performs best when initial mass fraction of R290 is about 0.7. The comparison results demonstrate that the novel cycle has great energy-saving potential.