The acceptance of the Montreal Protocol has led to a timetable for the
phasing out of chlorine-containing refrigerants and their replacement
by new chlorine-free materials. For many applications a pure alternat
ive refrigerant can not be found with the appropriate properties and r
efrigerant mixtures have been considered, In order to model the proper
ties of these refrigerant blends accurate vapour-liquid equilibrium (V
LE) data are required over the range of temperature and pressure of in
terest to the refrigeration engineer. In this paper we report VLE data
for six binary mixtures of the new hydrofluorocarbon refrigerants ove
r a wide range of temperatures and pressures. The six mixtures are: R3
2/R125, R32/R143a, R32/R134a, R125/R143a, R125/R134a and R143a/R134a,
Results for R32/R125 and R32/R134a were obtained down to at least -30
degrees C and were done in duplicate. The raw data were correlated to
two models using Maximum Likelihood techniques. One of the models was
then used to predict azeotropic compositions for three of the mixtures
(R32/R125, R32/R143a and R125/R143a) and the approximate composition
of a ternary saddle point azeotrope. (C) 1997 Elsevier Science B.V.