Exploring Low-Global Warming Potential Refrigerants for Medium-Charge Systems

The rising global warming potential (GWP) of refrigerants, particularly R-410A and R-134a, has driven the urgent need for environmentally friendly alternatives in cooling and heating systems. While low-GWP refrigerants are increasingly available for large and small refrigerant charge systems, a significant gap remains in identifying viable replacements for medium-charge applications, particularly in high and moderate climate conditions. This study addresses this critical gap by evaluating 15 lower GWP refrigerant options, including hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs), hydrochlorofluoroolefins (HCFOs), and hydrocarbons (HCs). The analysis focuses on their direct and indirect environmental impacts, ease of design integration, operational parameters such as capacity and efficiency, and economic feasibility. A novel aspect of this work is including internal heat exchanger performance as a function of refrigerant properties, offering unique insights into how system design can influence cycle efficiency. Key findings reveal that while several refrigerants can effectively replace R-410A in chiller applications, variable refrigerant flow systems present greater challenges due to performance and safety considerations. R-447A exhibits superior performance in standard ambient conditions among the studied refrigerants, whereas R-454B is better suited for high ambient environments. Additionally, refrigerants such as R-1233zde, R-1234yf, R-1234zee, R-1234zez, R-1243zf, and R-1336mzz(Z) demonstrate significantly lower total environmental weighted impact compared to R-410A, emphasizing their potential for reducing environmental harm. This study advances the current understanding of medium-charge refrigerant applications, providing actionable insights for researchers, policymakers, and manufacturers navigating the transition away from high-GWP HFCs.