VAPOR-LIQUID-EQUILIBRIUM (VLE) PROPERTIES OF R-32-134A SYSTEM DERIVEDFROM ISOCHORIC MEASUREMENTS(R)

Two methods developed for deriving Vapor-Liquid-Equilibrium (VLE) data from isochoric measurements are presented in this paper. The first, s o-called 'flash' method depends on a knowledge of the volumetric prope rties, estimated by means of an appropriate model; in the present case , the Carnahan-Starling-De Santis (CSD) equation of state (EOS) was us ed to predict the mixture's behavior. As for the second, so-called 'mo del-free' method, the first step is based on dew point evaluation by i nterpolating experimental P-T sequences. The dew point value obtained is then used to derive VLE data, again using the Camahan-Starling-De S antis equation of state. Two hundred twenty-five experimental P-V-T-x experimental data were obtained using a constant volume apparatus and 12 different binary mixture compositions prepared with the halogenated refrigerants difluoromethane (R-32) and 1,1,1,2-terafluoromethane (R- 134a}, in a temperature range of 240-360 K. From these experimental da ta the VLE properties were derived by using the two methods. A compari son of the results obtained against data in the literature shows consi stent agreement within the experimental uncertainty. (C) 1998 Elsevier Science B.V. All rights reserved.