Research Papers: Thermodynamic Properties

Supplementary Backward Equations v(p,T) for the Critical and Supercritical Regions (Region 3) of the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam

[+] Author and Article Information
H.-J. Kretzschmar2

Department of Technical Thermodynamics, Zittau/Goerlitz University of Applied Sciences, P.O. Box 1455, D-02754 Zittau, Germanyhj.kretzschmar@hs-zigr.de

A. H. Harvey

National Institute of Standards and Technology, Physical and Chemical Properties Division, Boulder, CO 80305

K. Knobloch, I. Stöcker

Department of Technical Thermodynamics, Zittau/Goerlitz University of Applied Sciences, P.O. Box 1455, D-02754 Zittau, Germany

R. Mareš

Department of Technical Thermodynamics, University of West Bohemia, CZ 306 14 Plzeň, Czech Republic

K. Miyagawa

 4-12-11-628 Nishiogu, Arakawa-ku, Tokyo 116-0011, Japan

N. Okita

Thermal Plant Systems Project Department, Toshiba Corporation, Yokohama 230-0045, Japan

R. Span, W. Wagner

 Ruhr-University Bochum, D-44780 Bochum, Germany

I. Weber

Siemens AG, Fossil Power Generation, D-91050 Erlangen, Germany


Corresponding author.

J. Eng. Gas Turbines Power 131(4), 043101 (Apr 13, 2009) (16 pages) doi:10.1115/1.3028630 History: Received May 20, 2008; Revised July 01, 2008; Published April 13, 2009

When steam power cycles are modeled, thermodynamic properties as functions of pressure and temperature are required in the critical and supercritical regions (region 3 of IAPWS-IF97). With IAPWS-IF97, such calculations require cumbersome iterative calculations, because temperature and volume are the independent variables in the formulation for this region. In order to reduce the computing time, the International Association for the Properties of Water and Steam (IAPWS) adopted a set of backward equations for volume as a function of pressure and temperature in region 3. The necessary numerical consistency is achieved by dividing the region into 20 subregions, plus auxiliary subregions near the critical point in which the consistency requirements are relaxed due to the singular behavior at the critical point. In this work, we provide complete documentation of these equations, along with a discussion of their numerical consistency and the savings in computer time. The numerical consistency of these equations should be sufficient for most applications in heat-cycle, boiler, and steam-turbine calculations; if even higher consistency is required, the equations may be used to generate guesses for iterative procedures.

Copyright © 2009 by American Society of Mechanical Engineers
Topics: Equations
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Grahic Jump Location
Figure 1

Regions and equations of IAPWS-IF97, IAPWS-IF97-S01, IAPWS-IF97-S03rev, IAPWS-IF97-S04, and the equations v3(p,T) of this work adopted as IAPWS-IF97-S05

Grahic Jump Location
Figure 2

Range of validity of the backward and auxiliary equations. The area in gray is not to scale but is enlarged to make the small area more visible.

Grahic Jump Location
Figure 3

Division of region 3 into subregions for the backward equations v3(p,T)

Grahic Jump Location
Figure 4

Enlargement from Fig. 3 for the subregions 3c–3r for the backward equation v(p,T)

Grahic Jump Location
Figure 5

Division of region 3 into subregions 3u–3z for the auxiliary equations




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