Experimental assessment of a low GWP nonflammable new refrigerant in a closed heat pump drying system

Abstract

Low global warming potential (GWP) refrigerants are vital to mitigating the effect of heat systems on climate change. A low GWP mixture, RGT2 (R134a/R1234yf/R161, 54%/43%/3% weight), was proposed as an alternative refrigerant for R134a in heat pump systems. This article presented the results of an experimental investigation evaluating RGT2 as a possible replacement for R134a in a closed heat pump drying (CHPD) system and studying the drying characteristics of fig slices. The experiment concluded that RGT2 has a higher coefficient of performance (COP hp ) value than R134a, on average, by 1.92%, achieving lower discharge temperature and pressure ratio at different condensing temperatures (45 C-70 C). Although the heating capacity of RGT2 was slightly lower, it still met the requirements of HPD. With careful consideration of the environment, performance, and safety, RGT2 was a suitable substitute for R134a in the drying field. In addition, the drying characteristics of fig slices were significantly affected by the air temperature. The effective diffusion coefficient (D eff ) and specific moisture extracted ratio (SMER) are increased by increasing temperature and air flow rate. The two-term model was the better model to accurately predict the fig slices drying process. The highest mean D eff and SMER of CHPDS were obtained as 6.4518 Â 10 À10 m 2 /s and 39.197 g/kWh, respectively, at the highest drying air temperature. Practical ApplicationA mixed refrigerant (RGT2) was proposed to replace R134a, and its GWP value was about 61% lower than that of R134a. Most of the studies on substituting R134a in the literature are simulations. This paper aims to evaluate the substitutions' feasibility theoretically and experimentally. The results have been assessed to provide better information about RGT2 as a potential substitute for R134a with superior comprehensive performance. Drying kinetics has also been determined experimentally, which helped to simulate fig drying. This study will provide a reference for refrigerants replacement in heat pump drying.