Vapor–liquid equilibria for CF 3OCF 2H/fluorinated ethane and CF 3SF 5/fluorinated ethane mixtures as potential R22 alternatives

Abstract

New vapor pressure data are reported as a function of temperature and concentration for the mixtures: CF 3SF 5/CF 3CH 3, CF 3SF 5/CF 3CF 2H, CF 3OCF 2H/CH 3CH 2F, CF 3OCF 2H/CH 3CF 2H, CF 3OCF 2H/CF 3CH 3, CF 3OCF 2H/CF 3CH 2F, and CF 3OCF 2H/CF 3CF 2H. As is expected, large positive deviations from the ideal mixing vapor pressure are observed for CF 3SF 5 mixed with ethane derivatives of a low fluorine content and these deviations become small as the fluorine content approaches that of CF 3CF 2H. In contrast to this expected vapor pressure behavior, the ether (CF 3OCF 2H)/fluorinated ethane mixtures exhibit significantly smaller deviations which may be positive or negative. The mixture, CF 3OCF 2H/CH 3CH 2F, exhibits sufficiently large negative deviations from ideality to produce an azeotrope at 0.21 mol fraction of CH 3CH 2F with boiling point of −33.3°C. The mixtures CF 3OCF 2H/CH 3CF 2H, CF 3OCF 2H/CF 3CH 3 and CF 3OCF 2H/CF 3CF 2H are nearly ideal and the mixture CF 3OCF 2H/CF 3CH 2F exhibits positive deviations from ideality. All of the mixtures have boiling points that range from −22 to −48°C. The mixtures that have boiling points below −30°C have potential as R22 alternatives.