| In
1995 the International Association for the Properties of Water
and Steam (IAPWS) released a new scientific-standard equation
of state called ”The IAPWS Formulation 1995 for the Thermodynamic
Properties of Ordinary Water Substance for General and Scientific
Use” (IAPWS-95). This new formulation replaces the previous
standard equation of state for the properties of water, the
IAPS-84 formulation.
The
comprehensive article on the IAPWS-95 formulation [127]
contains detailed information about the following topics:
-
Necessity of a new scientific-standard equation of state
for water
-
Phase equilibrium of water
-
Data used in the development of IAPWS-95
-
Details on the development of IAPWS-95
-
Numerical description of IAPWS-95 and further details
-
Comparison of IAPWS-95 with experimental data
-
Uncertainty of IAPWS-95
-
Recommendation on an improvement of the data basis
-
Annex: Steam table on the basis of IAPWS-95
The
following diagrams show the estimated uncertainties of IAPWS-95
for the properties density, speed of sound, isobaric heat
capacity in the homogeneous region and for the properties
vapour pressure and saturated liquid- and vapour density on
the liquid-vapour phase boundary.
|
Uncertainty
of IAPWS-95 in density (in pressure in the critical
region, left diagram) and in speed of sound (right
diagram). |
|
Uncertainty
of IAPWS-95 in the isobaric heat capacity (left diagram)
and on the vapour-liquid phase boundary in the three
properties vapour pressure pσ,
saturated liquid density ρ' and saturated
vapour density ρ'' (right diagram). |
The
three diagrams for the homogeneous phases also show the range
of validity of IAPWS-95. Apart from this formal range of validity,
IAPWS-95 can be reasonably extrapolated for the properties
pressure, density and enthalpy up to extremely high pressures,
temperatures and densities. (about 80000 MPa, some thousand
kelvins, about 2500 kg m−3)
Software
There
is an extensive software package available for the use of
IAPWS-95. This package is available as the program FLUIDCAL
in the version for the substance water, which is described
in the section software of this webpage.
Due
to the scientific relevance of IAPWS-95, the software for
the calculation of thermodynamic properties of water and steam
based on IAPWS-95 is available for universities free of charge.
Details
on the software FLUIDCAL can be found on this page.
|
