Experimental studies on a mixture of HFC-32/125/161 as an alternative refrigerant to HCFC-22 in the presence of polyol ester

Abstract

In this work, experiment was conducted to examine the thermo-physical properties of an alternative refrigerant to HCFC-22 in the presence of polyol ester (POE). The new alternative refrigerant is a mixture of HFC-32/125/161, whose physical properties are similar to HCFC-22 but has a lower global warming potential (GWP) than that of R407C. POE is used as the tested lubricating oil in the experiment. The saturated vapor pressure data and vapor–liquid equilibrium data of nine different mass fractions of the new refrigerant and polyol ester (POE) in the temperature range of 253–323 K were measured by single-phase cycle method. The experiment results showed that there was no stratification, no sediment generation in the liquid phase of the mixture, and the color of liquid phase of the mixture had no change in the equilibrium cell before and after the experiment with the POE concentration greater than 20% and the temperature higher than 258 K; with POE concentration lower than 20% and temperature lower than 258 K, stratification began to appear. Meanwhile, when POE and the refrigerant were miscible, the saturated pressure data of the mixture (HFC-32/125/161 + POE) revealed that POE had a very small impact on saturated vapor pressure of the mixture (almost negligible) when POE was less than 10% of the mixture; POE has an obvious effect on the saturated vapor pressure of the mixture when there is more than 10% POE in the mixture, especially when the temperature is higher than 283.15 K. Experimental data were correlated by Flory–Huggins model, Heil model, NRTL model and Wilson model. The results showed that to the average and maximum pressure deviation, the results were better with considering the effects of temperature on the energy parameters. Among the above models, the NRTL activity coefficient model was the best, the Heil and Wilson models followed and the Flory–Huggins model had the largest deviation from the experimental data.