Flammability limits of refrigerant mixtures with 1,1,2,2-tetrafluoroethane

Extensive measurements have been made on the flammability limits of two binary mixtures of propane/1,1,2,2-tetrafluoroethane and 1,1-difluoroethane/1,1,2,2-tetrafluoroethane as per the Chinese National Standard GB/T 12474-90. Experimental data for the 1,1,2,2-tetrafluoroethane mixtures were obtained with estimated uncertainties of 0.09 mol% for lower flammability limits and 0.14 mol% for upper flammability limits. All measurements were carried out at atmospheric pressure and room temperatures around 20 °C. It has been found that molar fractions of propane and 1,1-difluoroethane in lower limit mixture decrease when 1,1,2,2-tetrafluoroethane, being itself nonflammable, is added to the mixture. Modification was made to the extended Le Chatelier’s formula for interpreting the dilution effect of 1,1,2,2-tetrafluoroethane. It has been found that the extended Le Chatelier’s formula using an individual set of parameters can fit the experimental results for flammability limits of propane and 1,1-difluoroethane diluted with 1,1,2,2-tetrafluoroethane well.