Experimental evaluation of R454C and R495A in an R134a-based air conditioning system for new-energy vehicles

Low-global-warming-potential zeotropic blends can reduce the direct climate impact of electric-vehicle air conditioning, but their practical value depends on cooling capacity, compressor demand, and pressure level. This study experimentally assessed R454C and R495A in the single-AC mode of an integrated thermal-management platform originally developed for R134a. Charge optimization, thermodynamic screening, conventional cooling tests, parameter sweeps, an extreme 55 °C boundary, and evaporator outlet-air temperature mapping were performed. Under three representative cooling conditions, R454C delivered 5.23–7.71 kW, exceeding R134a capacity by 4.3–14.4% while requiring 41.3–47.5% lower compressor speed. R495A delivered 5.06–7.39 kW and achieved a COP 18.7–31.1% higher than that of R134a. Relative to R454C, R495A reduced discharge pressure by 27.7–33.0% and maintained substantially lower discharge temperature. Increasing condenser frontal air velocity from 2.0 to 4.5 m s⁻¹ increased capacity by 9.6–28.3% for R454C and 8.9–14.1% for R495A, whereas superheat primarily redistributed refrigerant inventory and increased discharge temperature. At 55 °C, performance was constrained by the compressor thermal envelope, especially for R454C. Despite their temperature glide, both blends reduced the evaporator outlet-air temperature span relative to R134a. R454C therefore favors volumetric capacity and compressor-speed reserve, whereas R495A offers a lower-pressure and lower-temperature route when adequate high-speed compressor capability is available.