Critical properties and vapor-liquid equilibrium of two near-azeotropic mixtures containing HFOs

This work studies two binary mixtures of R1243zf + R1234yf and R1243zf + R245cb which can be possibly used as a long-term alternative refrigerant for heat pumps. We present critical property (critical temperature, pressure, density) and vapor liquid equilibrium (VLE) of R1243zf + R1234yf and R1243zf + R245cb two binaries. The maximum extended uncertainties (k=2) are estimated as U(T) = 0.21 K, U(p) = 0.048 MPa, and U(rho) = 6.4 kg/m(3) for critical property measurement, and U(T) = 0.06 K and U(p) = 0.015 MPa for bubble point measurement. The uncertainty of liquid-phase mole fraction is estimated less than 1.8 x 10(-4). The critical property is investigated by a novel method that determines the critical point via modeling vapor-liquid coexistence points to the combined equations of the scaling law and rectilinear diameters law. The VLE of R1243zf + R1234yf and R1243zf + R245cb binary mixtures in the range of 293.45 to 353.55 K are studied by the static-synthetic method which determines the bubble point via the variable volume cell technique. The experimental bubble points are correlated by the Peng-Robinson (PR) equation of state (EoS) with vdW and MHV2 mixing rules. The modeling results are in good agreement with the measured data. The high temperature VLE of the two binary systems is predicted up to the critical point line by PR-MC-MHV2 model with the optimal binary parameters.

Automated summary

This study investigates the properties and vapor liquid equilibrium (VLE) of two binary mixtures, R1243zf + R1234yf and R1243zf + R245cb, which could be potential long-term alternative refrigerants for heat pumps. The critical properties and VLE were determined through experiments and modeling. The results show that these mixtures exhibit good performance at high temperatures.