Simple functions for the fast approximation of light water thermodynamic properties

Abstract

Thermalhydraulic systems analysis and simulation requires the fast and accurate generation of light water thermodynamic properties. An approach suggested in the past is the use of simple, non-linear functions to give approximations to the properties. Such functions have been developed and are presented here. The range of use is from 0.085 MPa to 21.3 MPa, and from 90°C to 450°C. In the subcooled and superheated regions the error for enthalpy, entropy and specific volume is usually much less than 1%. This error is based on comparisons to the latest internationally accepted formulation for the thermophysical properties of steam and water. These simple analytic functions provide an alternative to the use of linear interpolation algorithms and complex transcendental equations to generate light water thermodynamic properties. They are well suited to be made into computer subprograms, yet they are simple enough to be used with programmable calculators.