Determination of a suitable retrofit of R-134A using refrigerant blends of R290 and R600 aided by an optimization technique

Abstract

The effect of the hydrochlorofluorocarbon (HCFC) and hydrofluorocarbon (HFC) refrigerants on the environment through the attack of its halogen contents-chlorine and fluorine, on the ozone layer and the toxic nature of such refrigerants, has paid the attention of researchers to work towards getting suitable alternatives using hydrocarbons (HC) or its blends with HFC refrigerants. This study was centered on getting a suitable retrofit of R134A with a good coefficient of performance (COP) and low global warming potential (GWP) using the blends of R290 and R-600 HCs for use in refrigeration systems. An experimental testing rig was developed by assembling various measuring devices to the operational points of a vapor compression refrigerator. A mixture design was developed using the simplex lattice design (SLD) of design expert software 11.0. The response variables considered were COP and GWP. The experimental design was meticulously followed using 1kg for each refrigerant run, and the temperature and pressure values at the operating points were noted. From the results obtained, blend A had the highest COP of 2.5 and the highest GWP value of 3.93. Blend D had the lowest value of C.O.P. of 1.33, while blend B had the lowest value of GWP of 3.51. Also, the optimal blend was achieved at a mixture factor of 59% R-290a and 41% R-600. The response values obtained at this optimal mixture level were COP-2.05182 and GWP – 3.59. Therefore, the optimal blend obtained would be a better retrofit to R-134a and could be used in refrigeration systems.