In order to improve the cycle performance of a conventional single-stage autocascade refrigeration cycle (ARC), an auxiliary separator is considered to be introduced. In the modified autocascade refrigeration cycle (MARC), the auxiliary separator located after an expansion device is used to further collect the vapor enriched with low-boiling components. In this case, the MARC enables to improve the cycle performances by utilizing more zeotropic mixture enriched with the low-boiling components to realize a higher evaporation pressure at the given evaporation temperature in the evaporator of the cycle. The performances of the MARC and ARC are compared utilizing energy, exergy and exergo-economic analysis methods, and several important parameters are also discussed in detail. The results indicate that the MARC using zeotropic mixture R290/R170 is feasible and there are obvious improvements in terms of the COP, volumetric refrigeration capacity and exergy efficiency. It is found that compared to the ARC, the COP improvement of MARC can reach up to 16.1%. The exergy efficiency of MARC is increased by 10.23% and the overall cost rate of MARC is decreased by 2.51% under a typical operating condition. In addition, the COP of MARC has a maximum value at given conditions when the mass fraction of R290 at the compressor inlet is around 0.3. In general, the performance characteristics of the proposed cycle demonstrate its potential applications in low-temperature freezers.

为了改善常规单级自动级联制冷循环（ARC）的循环性能，考虑引入辅助分离器。在改进的自动级联制冷循环（MARC）中，位于膨胀装置之后的辅助分离器用于进一步收集富含低沸点组分的蒸气。在这种情况下，MARC可以通过利用更多的富含低沸点组分的共沸混合物来改善循环性能，从而在循环蒸发器中的给定蒸发温度下实现更高的蒸发压力。利用能量，火用和能经济分析方法比较了MARC和ARC的性能，并详细讨论了几个重要参数。结果表明，使用共沸混合物R290 / R170的MARC是可行的，并且在COP，容积制冷量和火用效率方面都有明显的提高。结果发现，与ARC相比，MARC的COP改进率可高达16.1％。在典型的运行条件下，MARC的火用效率提高了10.23％，MARC的总成本降低了2.51％。此外，当压缩机入口处R290的质量分数约为0.3时，MARC的COP在给定条件下具有最大值。通常，所提出的循环的性能特征证明了其在低温冰柜中的潜在应用。MARC的COP改善可达到16.1％。在典型的运行条件下，MARC的火用效率提高了10.23％，MARC的总成本降低了2.51％。此外，当压缩机入口处R290的质量分数约为0.3时，MARC的COP在给定条件下具有最大值。通常，所提出的循环的性能特征证明了其在低温冰柜中的潜在应用。MARC的COP改善可达到16.1％。在典型的运行条件下，MARC的火用效率提高了10.23％，MARC的总成本降低了2.51％。此外，当压缩机入口处R290的质量分数约为0.3时，MARC的COP在给定条件下具有最大值。通常，所提出的循环的性能特征证明了其在低温冰柜中的潜在应用。