Hydrogen-bonding of HFCs with dimethyl ether: evaluation by isothermal VLE measurements

Following our study on the hydrogen-bonding of HFCs with dimethyl ether, the vapour-liquid equilibria (VLE) (P-T-x-y,) data for the pentafluoroethane (R 125) + dimethyl ether (RE 170) and R 125 + propane (R290) systems are measured at 258.15, 273.15, 288.15 and 303.15 K by means of an apparatus based on the vapour recirculation. The estimated accuracies of measured data are +/-0.02 K for temperature, +/-1 kPa for pressure, +/-0.002 in mole fraction for both liquid and vapour phase by gas-chromatographic analysis. The R125+RE170 system shows strong negative deviations from the Raoult's law. The deviations are attributed to H-bonding between oxygen of RE 170 as proton acceptor and hydrogen of R 125 as proton donor. The H-bonding for the R125+RE170 system is estimated through the homomorphic concept, evaluating the physical interaction through excess Gibbs energy of the homomorphic R125+propane system. (C) 2002 Elsevier Science B.V. All rights reserved.