COMPARATIVE ANALYSIS OF THE IAPWS-IF97 FORMULATION PERFORMANCE FOR THERMODYNAMIC PROPERTIES OF WATER ON A RANKINE CYCLE

Abstract

The present paper presents the computational implementation of the industrial
formulation of the thermodynamic properties of water at liquid and
steam phases, proposed by the International Association for the Properties
of Water and Steam, known as IAPWS-IF97. The validity field extends over
to temperatures T between 0ºC and 800°C, for pressures p up to 100 MPa.
Temperature T, specific volume v, specific enthalpy h, specific entropy s,
specific heat at constant pressure cp and constant volume cv, besides saturation
pressure ps, are calculated having a pair of known input values (p,T),
(p,h) or (p,s). A comparative analysis between the IAPWS-IF97 routines
and others, based on foregoing propositions, from an application on Rankine
cycle, is made. IAPWS-IF97 has proved to be more precise, mainly because
it accounts for the region of compressed liquid, besides requiring less processing
time. The development is carried out as FORTRAN90 subroutines
and functions and is available for public use according to a General Public
License.