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

Published

July 1, 2009

Author(s)

H J. Kretzschmar, Allan H. Harvey, K Knobloch, Radim Mares, Kiyoshi Miyagawa, N Okita, Roland Span, I. Stocker, Wolfgang Wagner, I Weber

Abstract

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 six 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 discussion of their numerical consistency and the savings achieved in computer time. The numerical consistency of the equations documented here should be sufficient for most applications in heat-cycle, boiler, and steam-turbine calculations, and if even higher consistency is required these equations may be used to generate guesses for iterative procedures.

Citation

Journal of Engineering for Gas Turbines and Power-Transactions of the Asme

Volume

131

Pub Type

Journals

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Keywords

IAPWS, industrial calculations, steam, thermodynamics, water

Citation

Kretzschmar, H. , Harvey, A. , Knobloch, K. , Mares, R. , Miyagawa, K. , Okita, N. , Span, R. , Stocker, I. , Wagner, W. and Weber, I. (2009), 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, Journal of Engineering for Gas Turbines and Power-Transactions of the Asme, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=832251 (Accessed April 26, 2024)