SF-2129 -- Computer Calculation of the Theoretical Performance Properties of Fluorocarbon Refrigerants

Theoretical performance properties of refrigerants are calculated on the basis of physical and thermodynamic properties of any refrigerant assumed to be operating in a fixed refrigeration cycle. These theoretical values represent the optimum performance characteristics of the refrigerant in the cycle and assume an ideal mechanical system with perfect efficiency. The uses and applications of this type of data are numerous. Theoretical performance data are used by design engineers and scientists to determine the maximum obtainable efficiency of the refrigerant in a cooling cycle, and are also useful in evaluating and comparing the ideal performance characteristics of two or more refrigerants operating under the same cycle conditions. Further, comparisons of the theoretical performance values with those observed experimentally provide one measure of the efficiency of the refrigeration apparatus.

Although extensive tabulations of physical property and thermodynamic data for the fluorocarbon refrigerants have been available for some time, no corresponding tabulation of theoretical performance data were available. Previously, except for a few standard conditions, engineers and scientists had to choose appropriate data for the refrigeration cycle of interest and manually calculate the performance data for each refrigerant under a given set of conditions. To eliminate the need for this type of tedious manual calculation, a general computer program has been prepared which accurately calculates performance data for any given refrigerant assumed to be operating in a fixed refrigeration cycle. Using this general program, the performance data of interest in industrial applications have been calculated for refrigerants 12 and 22.

The calculation of performance properties using a digital computer requires a complete translation of physical property data and thermodynaqlic equations for each refrigerant into a general mathematical model which describes and mathematically simulates the conditions found in a refrigeration system. Based on this mathematical representation of the physical system, appropriate equations and thermodynamic expressions for the particular refrigerant are then adapted to a logic flow sequence for the actual calculation of-the performance data. This paper presents the details of the general computer program which was used to calculate the performance data for refrigerants 12 and 22.