In 1997, the International Association for the Properties of Water and Steam (IAPWS) adopted a new formulation for the thermodynamic properties of water and steam for industrial use. This new formulation, called IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (IAPWS-IF97), replaces the previous industrial formulation, IFC-67, that had formed the basis for power-plant calculations and other applications in energy engineering since the late 1960’s. IAPWS-IF97 improves significantly both the accuracy and the speed of the calculation of the thermodynamic properties compared with IFC-67. The differences between IAPWS-IF97 and IFC-67 will require many users, particularly boiler and turbine manufacturers, to modify design and application codes. This paper summarizes the need and the requirements for such a new industrial formulation and gives the entire numerical information about the individual equations of IAPWS-IF97. Moreover, the scientific basis for the development of the equations is summarized and the achieved quality of IAPWS-IF97 is presented regarding the three criterions accuracy, consistency along region boundaries, and computation speed. For comparison, corresponding results for the previous standard IFC-67 are also presented. [S0742-4795(00)02201-8]
Promotionauf dem Gebiet der landwirtschaftlichen Trocknungstechnik; seither geschäftsführender Oberassistent des Instituts, des jetzigen Instituts für Thermodynamik und TGA der TU Dresden. Die Deutsche Bibliothek -CIP-Einheitsaufnahme Repetitorium der Technischen Thermodynamik von Achim Dittmann ... (Teubner Studienbücher: Maschinenbau) NE: Dittmann, Achim Das Werk einschließlich aller seiner Teile ist urheberrechtlich geschützt. Jede Verwertung außerhalb der engen Grenzen des Urheberrechtsgesetzes ist I'ihrTe Zustimmung des Verlag~s unzulässig und strafbar. Das gilt besonders für Vervielfältigungen, Übersetzungen, MikroverfiJmungen und die Einspeicheruog und Verarbeitung in elektronischen Systemen.
In modeling advanced steam power cycles, thermodynamic properties as functions of pressure and enthalpy (p,h) or pressure and entropy (p,s) are required in the critical and supercritical regions (region 3 of IAPWS-IF97). With IAPWS-IF97, these calculations require cumbersome two-dimensional iteration of temperature T and specific volume v from (p,h) or (p,s). While these calculations in region 3 are not frequently required, the computing time can be significant. Therefore, the International Association for the Properties of Water and Steam (IAPWS) adopted backward equations for T(p,h), v(p,h), T(p,s), and v(p,s) in region 3, along with boundary equations for the saturation pressure as a function of enthalpy, p3sat(h), and of entropy, p3sat(s). Using the new equations, two-dimensional iteration can be avoided. The numerical consistency of temperature and specific volume obtained in this way is sufficient for most uses. This paper summarizes the need and the requirements for these equations and gives complete numerical information. In addition, numerical consistency and computational speed are discussed.
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