American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) article. A comprehensive compilation of the thermodynamic properties of R-22/R-12 Mixtures at saturation has been given in an earlier paper.' Since the properties of superheated vapors are also needed frequently while studying the performance of a refrigerating machine using these mixtures, the equations developed previously are now extended for the superheat region. The thermodynamic properties determined are specific volume, enthalpy and entropy. The equation of state and the equations for enthalpy and entropy developed for saturated conditions (eq 1, 23 and 31 respectively) are used to predict the superheated vapor properties at the required pressure and temperature (above saturation). The detailed derivations of these equations are given in Ref. 2. With the help of these equations, the superheated vapor properties are computed for eight different pressures, viz. 10, 20, 40, 60, 80, 100, 120 and 140 lbf/in 2 in the temperature range of -40 to 320°F. The following tables contain these properties at concentration intervals of 0.2. In order to facilitate interpolation, the properties of the pure components are also tabulated. These properties agree with those given in the charts 3 with a maximum deviation of 2%. For the mixtures, the accuracy of prediction in the temperature and pressure range used for tabulation is believed to be better than -I- 3%

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Mechanical Engineering (KGCOE)


RIT – Main Campus