Performance analysis of refrigeration system with ejector in using low GWP refrigerants

One of the causes of global warming is the use of refrigerants with a high global warming potential (GWP) value. Refrigerants with high GWP are intended to be banned gradually, with the enactment of international agreements and regulations. For this reason, researches have carried out on the use of low GWP refrigerants in vapor compression refrigeration (VCR) systems. System performance can be increased by adding equipment such as internal heat exchangers or ejectors to VCR systems. The proposed ejector is an effective system component in reducing the irreversibility in the VCR system and recovering the work during expansion. In this study, the performance parameters of a refrigeration cycle with an ejector are analyzed in the case of using low GWP refrigerants as an alternative to R134a. In order to improve the performance of the ejector refrigeration cycle used in this study, the system is designed with two evaporators and for R134a refrigerant. The experimental system was first tested with R134a and alternatively low GWP refrigerants R1234ze(E), ND, R515a, R456a and R516a were tested under steady-state conditions at different condenser temperatures. The performance parameters obtained in the case of using different refrigerants in the system have been analyzed comparatively. Considering the results, the two-evaporator refrigeration system with ejector could be operated successfully with all refrigerants with low GWP values. In addition, it was determined that the performance parameters obtained with R516a were very close to those with R134a and the COP value was 7% higher when the condenser temperature was 34°C. When examined according to the GWP value, it was determined that the best alternative to R134a among the refrigerants tested within the COP of the study was R516a. Similar results were obtained with R134a when the system was operated with R456a and ND, but GWP values should be considered when using these fluids. It was determined that the COP values of R1234ze(E) and R515a refrigerants were higher those of R134a, but their performance was found to be insufficient in terms of cooling capacities. Finally, R516a was found to be the best alternative to R134a for the system evaluated.