A simple way to derive physically based functional forms for approximate description of thermodynamic properties of gases is presented. The polynomials in transformed variables obtained are intended for fast industrial calculations. The approach is applied on eleven thermodynamic dependencies with pairs of independent variables most frequently encountered in turbine calculations. These functional forms were originally derived for the description of steam properties, but they are equally applicable to any gas in adequate region of state parameters. Approximation function for the dependence T(h, s) of steam is presented as an example including the values of 18 fitted parameters.

Issue Section:
Power
Topics:
Gases, Steam, Approximation, Polynomials, Turbines
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