Assessment of total equivalent warming impact (TEWI) of alternative refrigerants for retrofit of R22 in single split air conditioning system

Abstract

Since the adoption of the Montreal Protocol in 1987, until today, there have been several amendments to reinforce and even streamline the goals, encouraging industries to develop refrigeration systems that use low GWP refrigerants. In parallel to this, there is a large number of refrigeration units in developing countries, such as Brazil, which operate with high GWP fluids, such as R22, and discarding such equipment just because of the fluid would cause great damage not only to the owners, as well as for the environment. To reuse these units, this work aimed to evaluate alternative fluids that replace the current ones with the least possible modifications to the system without significantly compromising the performance of these sets. To achieve this, a mathematical model of a refrigeration system was developed and subsequently experimentally validated for R22. After that, this model was incorporated into a thermal zone, based on the environmental conditions of Belo Horizonte from December 2022 to November 2023 (one year) and the fluids R407C, R444B, and R454C were compared to R- 22 through COP, refrigeration capacity and Total equivalent warming impact of alternative (TEWI), in addition to analyzing environmental impacts. After the analyses, it was possible to notice that R407C performs worse than R22 in both performance parameters and TEWI. R454C has a COP and refrigeration capacity 16% and 11% lower than R22, respectively, however, it has a total TEWI 55% lower than the reference due to its low GWP. Finally, R444B was identified in this study as the best replacement alternative to R22 at mild temperatures, as it has COP and cooling capacity of 15% and 9% higher and has a TEWI that is also 55% lower than the reference.