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Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use

Developed by Russian National Committee (RNC) of

International Association for the Properties of Water and Steam (IAPWS).

This calculation page is based on the

"Revised Release on the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use" [1]

provided by IAPWS.

Detailed information about used equations, constants, range of validity etc is presented in PDF version of IAPWS Release which can be downloaded from IAPWS web site www.iapws.org

Authors (and responsible persons):

Moscow Power Engineering Institute (MPEI). Last update: 2013/01/15

Note that displayed last digits depends on numeric implementation of underlying formulations.

Input parameters

Formulation reference values

Dimensionless input parameters

Main equations

The specific Helmholtz free energy is represented by the equation

Eq. (4) in [1]

The ideal-gas part of the dimensionless Helmholtz free energy is represented by the equation

Eq. (5) in [1]

The residual part of the dimensionless Helmholtz free energy is represented by the equation

Eq. (6) in [1]

Dimensionless Helmholtz Free Energy and it's derivatives

The ideal-gas part of the dimensionless Helmholtz free energy

Coefficients from Table 1 [1] (can be downloaded here in text format):

Extracting data to vectors:

The derivatives of ideal-gas part of the dimensionless Helmholtz free energy

Eq. from Table 4 in [1]

The residual part of the dimensionless Helmholtz free energy

Coefficients from Table 2 [1] (can be downloaded here in text format):

Processing data in vectors for correct equations representation as in IAPWS Release [1]:

Additional values from Table [5] in [1] for further calculations of residual part of the dimensionless Helmholtz free energy and derivatives

The derivatives of residual part of the dimensionless Helmholtz free energy

Eq. from Table 5 in [1]

The dimensionless Helmholtz free energy and it's derivatives

Thermodynamic properties

Pressure:

Eq. from Table 3 in [1]

Compressibility factor

The internal energy

The specific entropy

The specific enthalpy

The specific isochoric heat capacity

The specific isobaric heat capacity

Speed of sound

Joule-Thomson coefficient

Isothermal throttling coefficient

Isentropic temperature-pressure coefficient

References

1. Revised Release on the IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use. Doorwerth, The Netherlands, September 2009, available at http://www.iapws.org