Experimental investigation of R600a as a low GWP substitute to R134a in the closed-loop two-phase thermosyphon of the mini thermoelectric refrigerator

Abstract

Various energy efficiency and environmental regulations around the world, such as the European Union's (EU) F-Gas regulation, are pushing refrigerator manufacturers to replace halogenated refrigerants with environmentally-friendly alternatives with low Global Warming Potential (GWP) without energy efficiency decrease. In this respect, increasing energy conversion performance by using a low GWP refrigerant in the mini thermoelectric refrigerators (MTERs) gains important for revealing sustainable and environmentally friendly refrigerators. To make this possible, the paper provides a comprehensive examination of the effect of climate-friendly refrigerant replacement in the closed-loop two-phase thermosyphon (CLTPT) on the performance of the MTER. This study treats the experimental investigation of the R600a as a low GWP substitute to R134a in the CLTPT of the MTER. Different from the other study in the literature, an extensive performance evaluation of the commercial MTER in terms of exergy as well as energy was performed and the various filling ratios (FR) of the R600a from 19% to 78% were analyzed for the best performance. The results showed that the MTER with a 46% and 32% FR of R600a had the highest exergy efficiency with 8.55% and 8.11%, respectively while reference MTER with R134a had 5.27%. It is concluded that 32% and 46% FR of the R600a enhanced the MTER energy conversion performance according to the 19% FR of the R134a, in line with the F-Gas regulation. The 32% and 46% FR of the R600a for MTER are the best refrigerant replacement, both from thermal performance and environmental points of view.