In a traditional vapor-compression refrigeration cycle (TVRC) of in the country refrigerator-freezers with R600a, the cycle system (single loop system) mostly The five basic elements, i.e., a compressor, a condenser, a capillary tube, a suction line heat exchanger (SLHX), and two evaporators in series (one for the freezer compartment and the other for the refrigerator compartment), as shown in Fig. 1. When the pure R600a is used, this TVRC system operates the two serial evaporators at the same evaporation temperature (pressure). For this reason, there is a larger temperature difference between the refrigerant and air in the refrigerator evaporator, and hence it causes more irreversible losses in heat transfer process. From exergetic point of view, this case may degrade the performance of the TVRC. When utilizing mixture R290/R600a in the TVRC, its temperature glide allows the evaporation temperature to increase at a constant evaporation pressure along the two serial evaporators. This means that the temperature difference between the refrigerant and air in the refrigerator evaporator is relatively small, resulting in small irreversible losses. It also may lead to improved system performance due to reduced irreversibilities of the refrigerator evaporator.