Thermodynamic Analysis of an Auto-Cascade Freezer Cycle at Different Loads of Evaporators

In this study, a modified auto-cascade refrigerating cycle is proposed. The cycle includes two evaporators and one compressor, and a separator is located after the refrigerator evaporator. The vapor phase from the separator is condensed through an internal evaporator and is mixed with some amount of the liquid phase taken from the separator. The condensed liquid is sent to the freezer evaporator at low pressure. Thermodynamic properties of the mixture R290/R600a, which is a zeotropic mixture as a cycle fluid, were determined using the REFPROP database. The variation of the cycle performance and total cooling capacity is investigated by changing the ratios of refrigerator and freezer loads. The results show that the volumetric cooling capacity increases and the compressor pressure ratio decreases as the load ratio of the refrigerator increases.