Vapor-liquid equilibria of novel chemicals and their mixtures as R-22 alternatives

Vapor-liquid equilibrium (VLE) vapor pressures are reported for binary mixt ures; octafluoromethylethylether + 1, 1-difluoroethane (RE218/R152a), trifl uoromethylpentafluorosulfur(VI) + 1,1-difluoroethane (CF3SF5/R152a), hexafl uorodimethylthioether+ 1,1,1,2-tetrafluoroethane (CF3SCF3/R134a), and penta fluorodimethylether+ 1, 1,1-trifluorodimethylether (RE125/RE143a). The mixt ures; (RE218/R152a), (CF3SF5/R152a), and (CF3SCF3/R134a) form minimum boili ng azeotropes with the normal boiling points; 237.9 K (-35.3 degreesC), 239 .7 K (-33.5 degreesC), and 243.0 K (-30.2 degreesC), respectively, and gas- liquid critical temperatures of 353.3 K (80.1 degreesC), 365.7 K (92.5 degr eesC) and 368.2 K (95.0 degreesC), respectively. The azeotropic mixtures ha ve sufficiently low boiling points to serve as alternatives for the refrige rant R-22 (CHF2Cl). The mole fractions of the perfluorinated component of t hese mixtures at the azeotropic compositions are 0.49, 0.41, and 0.46, resp ectively. The estimated critical mixing temperatures for liquid-liquid phas e separation are 236 K (-37 degreesC:), 221 K (-52 degreesC), and 341 K (-6 8 degreesC), respectively, and are well below the corresponding boiling poi nts. The ether mixtures, (RE125/RE143a), exhibit nearly ideal mixing behavi or which contrasts the VLE behavior of mixtures of perfluorinated ether, RE 218, with RE143a [I. Kul, D.D. DesMarteau, A.L. Beyerlein, ASHRAE Trans. 10 6 (1) (1999)1. In addition to binary mixtures, VLE data are reported on fou r ternary mixtures; RE125(33%)/R134a(33%)/R161(34%), RE125(33%)/RE143a(33%) /R161(34%), RE218(33%)/RE143a(33%)/R161(33%), and RE218(40%)/RE143a(40%)/R1 61(20%) with boiling points 240.6 K (-32.6 degreesC), 241.6 K (-31.6 degree sC), 236.7 K (-36.5 degreesC), and 238.6 K (-34.6 degreesC), respectively. The boiling points of the ternary mixtures are sufficiently low for a R-22 alternative. (C) 2000 Elsevier Science B.V. All rights reserved.