This research is part of an effort in finding viable alternative refrigerants to mitigate anthropogenic climate change. In this study binary zeotropic mixtures of selected hydrocarbons (HCs) with carbon dioxide (CO₂) are evaluated as alternative refrigerants for a vapor-compression refrigeration cycle. A thermodynamic analysis of these mixtures is performed for a cycle with a variable temperature of energy transfer fluid in both evaporator and condenser/gas cooler. A temperature glide matching method with a specified minimum temperature difference between refrigerant and energy transfer fluid in the energy exchangers was developed for performance maximization. This method does not require any experimental input or an educated guess for the temperature difference between refrigerant and energy transfer fluid and can simulate both sub-critical and trans-critical cycles. Performance metrics like the coefficient of performance (COP) and volumetric refrigeration capacity (VRC) are calculated and discussed for various mixture compositions (0 to 100% CO₂). Furthermore, non-dimensional exergy destructions in different components in the cycle are determined to estimate the effect of individual components on the total performance. An increase up to 40% in COP for zeotropic mixtures of HCs and CO₂ is observed when compared with pure HCs. The VRC is also shown to increase with increasing CO₂ concentrations in HC + CO₂ mixtures. Exergy analysis shows a decrease in non-dimensional exergy destruction in the energy exchangers due to temperature glide matching.

这项研究是寻找可行的替代制冷剂以减轻人为气候变化的努力的一部分。在这项研究中，选定的碳氢化合物（HCs）与二氧化碳（CO ₂）作为蒸汽压缩制冷循环的替代制冷剂进行评估。在蒸发器和冷凝器/气体冷却器中，对这些混合物进行热力学分析，以进行一个可变温度的能量传递流体循环。为了使性能最大化，开发了一种温度滑动匹配方法，在制冷剂和能量交换器中的能量传递流体之间具有指定的最小温差。该方法不需要任何实验输入或对制冷剂和能量传递流体之间的温差的有根据的猜测，并且可以模拟亚临界和跨临界循环。计算并讨论了各种混合物成分（0至100％CO的性能指标，如性能系数（COP）和制冷量（VRC））₂）。此外，确定循环中不同组件的无量纲火用破坏，以估计单个组件对总体性能的影响。与纯HC相比，HC和CO _2的共沸混合物的COP最高增加40％。VRC还显示出随着HC + CO ₂混合物中CO ₂浓度的增加而增加。火用分析显示，由于温度滑动匹配，能量交换器中的无量纲火用破坏减少。