PVTx and VLE properties of refrigerant mixtures from isochoric and Burnett experiments

摘要

This paper presents a summary of the results of PVTx and VLE measurements with the isochoric and Burnett methods obtained at our laboratory for the refrigeration systems of interest. The isochoric measurements were taken with two different apparatus: a primary version of the isochoric apparatus covering temperatures from 60 K to 370 K and a re-designed set-up covering a wider temperature range from 14 K to 370 K, with operating pressures up to 60 MPa in both cases. The measurements were taken for both the two-phase and the superheated vapor regions, and mixtures were prepared gravimetrically. The VLE parameters and density of the superheated vapor were derived from the data. The Burnett apparatus consists of two pressure vessels, a measurement chamber and an expansion chamber, both spherical in shape, with a volume of approximately 70 and 35 cm{sup}3, respectively. The classical Burnett experimental procedure was followed, repeating expansions until low pressures were achieved. The operating parameters of the Burnett experiment covered a temperature range from 83 to 365 K, and pressures up to 60 MPa. The virial coefficients were derived from the data. The study included twelve pure refrigerants and fifteen binary systems, and a complete list is reported. Of the systems studied, the results obtained for a group of binary systems composed of two natural refrigerants (R744, R744A) each of them with series of HFCs (R23, R3, R41, and R125), FC (R116), and R170 are presented because they are of particular interest for low-temperature applications.