ASME Steam Table, known as IFC-67, is the most widely used to estimated water or steam physical properties. However, it has been officially replaced by a new formulation known as IAPWS-IF97.

Actually, the most accurate formulation is IAPWS-95, which stands for "IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use". IAPWS-IF97 is designed to meet special industrial needs: fast computation and no frequent change [1]. IAPWS-IF97 is now "the international standard for calculations in the steam power industry" [2].

Compatible Software

There are many software compatible with IAPWS-IF97 or IAPWS-95.

• Excel Addins

There is a free Excel Addins [3], water97_v13.xla, available online, which can calculate water and steam properties for temperatures 273.15 K < T  < 1073.15 K and pressures 0 < p  < 1000 bar. This add-ins can make it possible to simulate or optimise steam system in spreadsheet.

The above Addins can only calculate single phase properties. I developed a spreadsheet template to deal with physical properties for water/steam two-phase mixture (click here to download).

• HTRI

HTRI implements IAPWS-IF97 in its HTRI Databank by selecting Water (IAPWS-IF97) component or VMGThermo property package by selecting steam95 method if water or steam is used as hot or cold fluid [4].

• Aspen

Aspen plus 12.1 uses STEAM-TA (ASME 1967 steam table) and  STEAMNBS (consistent with the model of IAPWS-IF97) [5]. 

Comparison Among Steam Tables [6]

• The IAPWS Formulation for General and Scientific Use (IAPWS-95)

This is the formulation approved by the International Association of the Properties of Water and Steam (IAPWS) in 1995 for general and scientific use. This formulation provides the most accurate representation of the thermodynamic properties of water an steam over a wide range of temperature and pressure.

• The IAPWS Formulation for Industrial Use (IAPWS-IF97)

This is the IAPWS approved formulation of industrial and special use. The industrial formulation is based on an approximation of the scientific formulation and is generally used in situations where computational speed is of importance. The IAPWS-IF97 formulation is recommended by the IAPWS be used as the basis for contracts beginning January 1, 1999, with respect to performance test calculations for those machinery and systems using steam . The IAPWS-IF97 replaces the previous IFC-67.

• The NBS/NRC Formulation (NBS/NRC-84) (used in Aspen STEAMNBS method)

This is the previous standard formulation approved for scientific and general use by the IAPWS in 1984. The work was done by members of the National Bureau of Standards and the National Research Council of Canada.

• The Industrial Formulation of 1967 (IFC-67)

This, older, but widely accepted, formulation is based on the 1967 IFC formulation for industrial use. This formulation is also the basis of the ASME Steam Tables, 6th Edition.

• Keenan and Keyes (1969)

Probably the most widely known and used Steam Tables authored by J. H. Keenan, F. G. Keyes, P. G. Hill, and J. G. Moore.

References

1. What is the difference between the IAPWS-95 formulation "for general and scientific use" and the IAPWS-IF97 "industrial" formulation?
2. How do IAPWS standards relate to the ASME Steam Tables?
3. Thermodynamic and Transport Properties of Water and Steam
4. HTRI help files
5. Thermodynamic properties of humid air and their application in advanced power generation cycles, Doctoral Thesis in KTH-Royal Institute of Technology.
6. What are the different formulations for the thermodynamic properties of water and steam?