Measurement and Correlation of Isothermal Vapor-Liquid Equilibrium of 1,1,1,3,3-Pentafluoropropane plus N,N-Dimethylacetamide and 1,1,1,3,3,3-Hexafluoropropane plus N,N-Dimethylacetamide/Diethylene Glycol Dimethyl Ether Systems

According to the structure feature of the absorption power cycle, three binary systems 1,1,1,3,3-pentafluoropropane (R245fa) + N,N-dimethylacetamide (DMAC), 1,1,1,3,3,3-hexafluoropropane (R236fa) + DMAC and R236fa + dimethyl ether diethylene glycol (DMEDEG) were identified as potential working fluids. The vaporliquid equilibrium (VLE) data of these three systems were measured over a temperature range of 293.15 K to 353.15 K and a pressure range of 20 MPa to 800 kPa. The five-parameter nonrandom two-liquid (NRTL) model was used to fit the experimental data. The average relative deviations in the pressure between the experimental and calculated data for R245fa + DMAC, R236fa + DMAC and R236fa + DMEDEG were 1.51 %, 1.61 % and 1.25 %, respectively, and the maximum relative deviations were 3.21 %, 3.52 % and 2.96 %, respectively. The calculated data were in good agreement with the experimental data. The three working fluids all displayed negative deviations from Raoults law, and the deviations decreased in the following order: R236fa + DMEDEG > R236fa + DMAC > R245fa + DMAC.