Scientific African (Nov 2020)
Theoretical assessment of new low global warming potential refrigerant mixtures as eco-friendly alternatives in domestic refrigeration systems
Abstract
Refrigerants of low global warming potentials (GWPs) of ≤ 150 are required by regulations as working fluids in domestic refrigeration systems. Therefore, this study theoretically investigated the performance of five new refrigerant mixtures (R440A, R441A, R444A, R445A and R451A) with zero ODP and GWPs of less than 150. The results showed that all the investigated refrigerants exhibited very low pressure ratios and discharge temperatures in comparison with R134a with average discharge temperatures of R451A and R440A lower by 8 and 7% respectively, than that of R134a. R451A and R440A have similar vapour specific volume and pressure-temperature characteristics with those of R134a which confirmed that they could be used as replacement for R134a. R440A and R451A have advantages of better COPs and volumetric cooling capacity (VCC) in comparison with R134a. Their average COPs are higher by 14 and 5% respectively, than that of R134a. The specific power consumptions (SPCs) of R441A and R445A are significantly higher by average of 57 and 44% respectively; while those of R440A and R451A are lower by average of 8 and 4% respectively, in comparison with R134a. In general, in terms of all the performance parameters considered, R441A and R445A consistently performed poorly, while R440A and R451A achieved better performance than R134a in all aspects. Beside the flammability of these two refrigerants, in which their use require following the established rules and regulations for the safety precautions, they can serve as long term eco-friendly substitute refrigerants for R134a in domestic refrigerators.
