Vapor–liquid equilibria of difluoromethane + N,N-dimethylacetamide, difluoromethane + dimethylether diethylene glycol and 1,1-difluoroethane + dimethylether diethylene glycol systems

The vapor–liquid equilibrium (VLE) data of difluoromethane (R32) + N,N-dimethylacetamide (DMAC), difluoromethane (R32) + dimethylether diethylene glycol (DMEDEG) and 1,1-difluoroethane (R152a) + dimethylether diethylene glycol (DMEDEG) systems have been measured over a temperature range from 293.15 to 353.15 K, using the static-analytical method with liquid phase sampling of the online mode. The experimental data were correlated with the five-parameter nonrandom two-liquid (NRTL) model. For the systems R32 + DMAC, R32 + DMEDEG and R152a + DMEDEG, the average relative deviations of the pressure were 1.25%, 1.66% and 1.67%, respectively and the maximum relative deviations of the pressure were 3.09%, 3.65% and 3.63%, respectively. The calculated results and the experimental data obtained a good consistency. The p–x diagrams related to refrigerant R32 exhibit obviously wider experimental data scale than that related to absorbent DMEDEG. It means that the system pressure mainly depends on the refrigerant but not the absorbent. As the alternative working pair, the suitability order from high to low is arranged as R32 + DMEDEG > R134a + DMF > R32 + DMAC > R152a + DMEDEG, showing the system R32 + DMEDEG is the best. The affinity between the refrigerant and absorbent was assessed on the characteristics of the species molecular structure for the three binary systems