Experimental Studies On Vapor Pressures Of New Refrigerants And Composition Analyses Of Binary Hydrofluorocarbon (HFC) Mixtures

Since 1990's, the search for new and environmentally accepted alternative refrigerants becomes an urgent issue in the fields of refrigeration, air-condition and heat pump. Mixture refrigerants are considered as promising alternatives due to their special advantages, while the corresponding researches on thermophysical properties, especially on the analysis of mixture composition and the vapor pressure of new substance, are still limited. Based on accurate experimental measurements and theoretical analyses, this dissertation studied the analysis methods of mixture composition and vapor pressures of some new refrigerants.A new gas-chromatogram apparatus for the analysis of mixture composition was developed. To find the relation between composition in mass fraction and ratio of peak area, a series of gas chromatographic analyses on nine kinds of binary hydrofluorocarbon (HFC) mixtures were performed. At the same time, a basic experimental data group was given for the development and choice of a new gas chromatographic analytic method. According to gas chromatographic analytic theory, a new method named the Standard Curve Function Method was presented including three models. The corresponding three models for all of the nine binary mixtures were developed based on the present experimental results.The pressure measurement system and the vacuum and mixture preparation system in the apparatus were improved. The vapor pressures of HFC-143a, HFC-227ea, HFC-236fa, HFC-245fa, propane and isobutane were measured. Three corresponding vapor pressure equations for HFC-143a, HFC-227ea and isobutene were developed on the basis of present measurements and available data. And two vapor pressure equations were proposed for HFC-236fa and HFC-245fa based on the present measurements, respectively. Then the normal boiling points and Pitzer factors of HFC-227ea, HFC-236fa, HFC-245fa and isobutane, were determined.