To investigate the vapor injection performance of a scroll compressor with a short profile, a three-dimensional transient numerical model of a vapor-injection scroll compressor for an electric vehicle with a displacement of 38 cm³/r is established and verified with deviations within 9.5%. We investigated the effects of the pressure and temperature of vapor injection on the performance of the scroll compressor using the model. The results show that under the condition of a constant superheat, with an increase in injection pressure, the discharge temperature of the compressor initially decreases and then gradually increases. Moreover, the heating capacity exhibits an increasing trend, with the maximum increase in heating capacity reaching 20.5% and 17.1% at rotary speeds of 5000 and 6000 r/min, respectively. In addition, the heating coefficient of performance (COP) increases during the first stage and then decreases. Moreover, the maximum values of the heating COP with vapor injection at the former speeds were 3.9% and 2.3% higher than those without vapor injection, respectively. The compressor efficiency exhibits the same tendency as the heating COP, and the volumetric efficiency gradually decreases. The compressor discharge temperature increases slightly with constant injection pressure, whereas the compressor power, heating capacity, and heating COP remain almost constant as the injection temperature increases. Compared with the injection temperature, the injection pressure has a significant impact on the scroll compressor.

R404A is widely used in light commercial equipment. However, the Kigali Amendment currently specifies the refrigerant replacement process. R454C and R290, owing to their low global warming potential values, have become promising refrigerants for use in commercial refrigerators. To compare the performances of these three refrigerants in commercial refrigerators, this study uses a climatic chamber to test four commercial refrigerators of different sizes. Four key parameters, namely the refrigerant charge, energy consumption, material cost, and carbon emissions, of the R404A, R454C, and R290 systems were compared. The results indicated that replacing R404A with R454C resulted in energy savings of approximately 5% and a reduction of approximately 15% in carbon emissions. When using R290, the charge was only 20.6%-34.3% of that of R404A, remaining within a safe range. Additionally, the charging cost was only half that of R404A. Furthermore, the system satisfied the performance requirements with this charge amount, leading to a reduction in energy consumption and carbon emissions within the ranges of 15%-35% and 25.3%-43.7%, respectively.