Separation of hydrofluoroolefins (HFOs)/hydrofluorocarbons (HFCs) from new-generation refrigerant mixtures has become critical to promote refrigerant recycling use and greatly reduce the emission of HFC refrigerants having high global warming potential. In this study, the utilization of ionic liquids (ILs) as ideal separation agents is explored for the separation performance of mixtures of HFCs (R-32, R-227ea, R-134a, R-152a, and R-125) with HFOs (R-1234yf and R-1234ze(E)). The thermodynamic absorption equilibria of R-134a, R-227ea, R-152a, R-32, and R-125 in [P 6,6,6,14 ][Cl] were measured at temperatures from 293.15 to 343.15 K and pressure up to 1.4 MPa. R-227ea shows the highest solubility, while R-32 shows the lowest solubility, suggesting that the absorption of HFCs in ILs is mainly related to their Hbonding capability. The measured data were successfully correlated by the equilibrium equation combined with the NRTL model, which provides a theoretical tool used for the separation process design. Moreover, the separation capacity was assessed for HFC/HFO blends in imidazolium-and phosphonium-based ILs using ideal selectivity. Considering the ideal selectivity, viscosity, and cost of ILs, [P 6,6,6,14 ][Cl] may be a good candidate for an entrainer for separating some azeotropic or close-boiling-point HFC/HFO mixtures.

Owing to zero ozone depletion potential (ODP) and extremely low global warming potential (GWP), 2,3,3,3tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-tetrafluoropropene (R1234ze(E)) as most potential refrigerants have attracted much interest in refrigeration and air conditioning (RAC). For a better insight into the refrigeration performance using R1234y and R1234ze(E) as refrigerants, the thermophysical properties of refrigerant/lubricant blends should be well understood, especially the viscosities of the refrigerant/lubricant blends. Using a selfdesigned-capillary apparatus, the viscosity measurements were performed for blends of POE85 oil saturated with R1234y and R1234ze(E) between 303.15 and 343.15 K. Viscosities of both R1234yf/POE85 and R1234ze(E)/POE85 have a similar trend. With an increase in solubility, the viscosity plunges dramatically at the beginning and then drops slowly. The results indicate that the refrigerant dissolved in oil has a large impact on the lubricant viscosity. The experimental data were successfully correlated by Eyring's absolute rate theory coupled with modified two-suffix-Margules (Eyring-MTSM model).

This study investigates the application of gravity gradient and aerodynamic torques in the attitude control and momentum management (ACMM) of the space station. Due to the large inertia and solar panels, environmental torque is significant enough in the ACMM in order to save fuel costs. Towards this end, the gravity gradient and the solar panels' aerodynamic models are established. The weighted-state H controller is designed since the attitude control sub-system is much slower than the momentum management sub-system. Numerical results are shown to demonstrate the practicability of the environmental torque application and the effectiveness of the weighted-state H technique.

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In this work, solubilities were measured for R-1233zd(E) in PVE 68 oil between (283.15 and 343.15) K using an isochoric saturation method. The nonrandom two liquid (NRTL) model was applied to represent the solubility behavior of the R-1233zd(E)/PVE 68 oil mixture. According to the experimental data, we studied the differences in enthalpies between pure R-1233zd(E) and the R-1233zd(E)/PVE 68 oil mixture as well as the oil effect on the evaporator performance with different superheating and oil circulating mass fractions (C g ). In the pressure−enthalpy−vapor quality diagram, isotherm curves of pure R-1233zd(E) and the R-1233zd(E)/oil mixture have a separation point called the critical vapor quality that is mainly connected to solubility and C g . Moreover, the enthalpy change rate (R h ) and nonevaporation quality (NEQ) are also associated with the solubility and C g , especially at low superheating. A lower solubility and C g will result in higher R h and lower NEQ, which are favorable to the refrigeration cycle.