Energy and Consumption Fuel Study for a Mobile Air Conditioning System Using Ejector and R445A As a Replacement Alternative for R134a

Vapor compression refrigeration systems (VCR) continue to be the most widely used type of air conditioning system for automobiles, however, they represent high energy consumption and, due to the use of R134a as a refrigerant fluid, they induce a significant environmental impact. Although investigations have increased over the last three decades, alternative automotive air conditioning systems (MACs) are not yet fully developed. Among these opportunities is the replacement of the traditional expansion device used in VCR systems with an ejector which represents low investment costs, lower losses can be achieved during the expansion process, and contribute to the recovery of work in the compressor, this reduction in the work consumption of the MACs produces a lower fuel consumption of the automobile engine. Due to international regulations regarding the use of refrigerants in automotive air conditioning systems, R134a is a fluid that is already being phased out. Before this action, various options were proposed to match or even exceed the energy performance that R134a offered in MACs. One option that emerges from all of them is R445A, especially since it fully complies with the low GWP limit set in the Normative EU-517/2014. In this work, the basic refrigeration cycle (BRC) is modeled and compared to the refrigeration cycle configuration that uses an ejector (EC). Both models were made using R134a and R445A to compare the influence of the ejector and the low GWP refrigerant. The results show that the EC with R445A reaches increases in COP from 4.1 to 15.6%, compared to that obtained in BRC mode, in addition to reducing power consumption in the compressor from 2.7 to 11.3%. On the other hand, when comparing the COP of the EC with R445A and the BRC using R134a, increases of up to 6.3% are observed in favor of R445A and a power requirement of 14.3% less for R445A compared to R134a. In addition, when evaluating the fuel consumption in volume per unit of time, the EC configuration proposed with R445A reduces the fuel required for this system by up to 40.4% for an evaporating temperature of 5°C, in the same way, for the evaporation conditions of 10 and 15°C, lower fuel requirements were obtained between 18.1 and 35.5%, this compared to the base system, R134a in BRC mode. Finally, by varying the condensing temperature in a range from 35 to 55°C, the fuel requirement increased, however, the EC configuration maintained the trend towards savings in the required fuel flow concerning the BRC.