Abstract
The paper presents relatively simple approximate analytic expressions showing the dependence of the compressibility factor, specific enthalpy and specific entropy of dissociating steam on pressure and temperature. The range covered by these expressions extends from 1000 to 5000°K, and from 0·01 to 100 bar. The deviations of the approximate analytic expressions deduced in the paper, from data obtained through complete thermodynamic calculations, are of the order of 1·5 per cent, i.e. practically the same as the errors of the complete calculation. The advantages offered by the use of the approximate expressions are a computation time of about 50 per cent and a digital computer storage occupation of about 60 per cent of the values corresponding to the complete calculation, while the fact that the approximate expressions are not generally thermodynamically consistent within the whole range constitutes a certain shortcoming.
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