Isothermal vapor–liquid equilibrium measurements and assessments of 1,1,1,3,3,3-hexafluoropropane+N,N-dimethylformamide/N-methyl-2-pyrrolidone working pairs for absorption power cycles

Measurement and Correlation of Vapor–Liquid Equilibrium for R124 (1-Chloro-1,2,2,2-Tetrafluoroethane)-NMP (N-Methyl-2-Pyrrolidone) and R124-DMF (N,N-Dimethylformamide) Mixtures

“…In order to measure the VLE data of R124-NMP and R124-DMF binary mixtures, the experimental principle given by refs 5, 8, and 10 was adopted in this paper and a VLE measurement system showed in Figure 1 was set. The system composed of some apparatuses which are (1) thermostatic water bath, (2) equilibrium still, (3) temperature controller, (4) refrigerator, (5) vacuum pump, (6) temperature sensors, (7) pressure sensors, (8) refrigerant cylinder, (9) refrigerant storage tank, (10) valves, (11) computer, (12) liquid injector, (13) six-way metering valve, and (14) gas chromatography (GC). The types, operation parameters and measurement accuracy of those apparatuses are listed in Table 1.…”

“…28 The five-parameter NRTL model had been successfully employed in correlating the experimental VLE data for binary mixtures, like R161-DMAC or NMP, R236fa-DMF or NMP. 10,11 So, the NRTL model with five parameters was also selected to correlate the VLE data of R124-NMP and R124-DMF from 303.15 to 363.15 K in this paper. The model is expressed as follows (5)…”

“…On the contrary, when the activity coefficient of refrigerant composition in the solutions is more than 1, the solutions appear as a positive deviation from Raoult's law and the absorbent in them have a weak affinity for refrigerant. 2,30,31 Figure 8 illustrates the variations of activity coefficients of R124 (γ 1 ) in three binary solutions, R124-NMP, R124-DMF, and R124-DMAC with respect to mole fraction (x 1 ) at the temperature of 303.15 and 363.15 K, respectively. In the figure, two solid curves are results correlated by the five-parameter NRTL model, the tabs near the curves are measurement data points and the isolated tabs are results calculated by the regression equation given in ref 13.…”

“…The NRTL model is an excellent predictive tool for the VLE of nonideal systems , So, the NRTL model with five parameters was also selected to correlate the VLE data of R124-NMP and R124-DMF from 303.15 to 363.15 K in this paper. The model is expressed as follows …”

“…Jing et al measured the VLE data of R161-DMAC, R161-NMP, and R134a-DMAC mixtures in a temperature range from 293.15 to 353.15 K. All of the data were also correlated by the five-parameter NRTL model. Yan et al measured the VLE data of R236fa-DMF and R236fa-NMP mixtures in a temperature range from 293.15 to 353.15 K. The results make clear that two mixtures can be used as potential working fluids for absorption power cycle. The results are also compared with their previous works …”