About Steam97Web

 

Thermodynamic and Transport Properties of Water and Steam
 
The steam tables application calculates 32 thermodynamic and transport properties of water and steam. It allows 16 different combinations of input variables to be used for calculations. Input variables that can be used are: pressure, temperature, enthalpy, entropy, volume, internal energy and steam quality.

The application uses new industrial formulation for steam tables, called "IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam (IAPWS-IF97)", and replaces the previous industrial formulation, IFC-67. IAPWS-IF97 improves significantly both accuracy and speed of the calculation of the thermodynamic properties compared with the old formulation. For transport properties calculations are based on the latest internationally accepted equations also available from IAPWS.

NEW

The application also enables calculation of thermodynamic and transport properties of water and steam based on the Scientific Formulation IAPWS-95.
This is the most accurate formulation for calculating properties of water and steam available today.


Introduction to IAPWS-95
 
In 1995, the International Association for the Properties of Water and Steam (IAPWS) adopted a new formulation for the thermodynamic properties of water and steam for general and scientific use, called "The IAPWS Formulation 1995 for the Thermodynamic Properties of Ordinary Water Substance for General and Scientific Use". This new formulation, called IAPWS-95 provides the most accurate representation of the thermodynamic properties of the fluid phases of water substance over a wide range of conditions.

IAPWS-95 is a fundamental equation of Helmholtz free energy as a function of temperature and density, which yields other thermodynamic properties by differentiation and algebraic manipulation without the use of any other information. IAPWS-95 defines accurately the thermodynamic properties of ordinary water substance, with complete thermodynamic consistency between these properties, over a wide range of states. Thus IAPWS-95 is recommended as the source of the thermodynamic properties of water and steam. However, since the independent variables of IAPWS-95 are temperature and density, computing times for some applications may be excessive. Because of that IAPWS-IF97 was developed, to provide almost as accurate results, but at a much faster speed.


Introduction to IAPWS-IF97
 
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 calculation and other applications in energy engineering since the late 1960's. IAPWS-IF97 improves significantly both accuracy and speed of the calculation of the thermodynamic properties compared with IFC-67.
 

Advantages of IAPWS-IF97
 
The driving force behind the development of the new formulation was increased computing speed. This effort was promoted by the power industry, which makes extensive use of steam properties in preparing power cycle calculations.
 
There are a number of important advantages which IAWPS-IF97 has over the old industrial formulation IFC-67, these include:

• Improved Consistency at Interregional Boundaries
• Better Agreement with Scientific Formulation (IAWPS 95)
• Improved Calculation Speed
• Agreement with ITS-90 International Temperature Scale
• New High Temperature Region
• Properties of Metastable Steam

Thermodynamic properties

Range of validity
Industrial Formulation (IAPWS-IF97)
 
The entire set of equations of IAPWS-IF97, used by the application for calculation of thermodynamic properties, is defined by the following temperature and pressure range:

• 273.15 <= T <= 1073.15 K       p <= 100 MPa
• 1073.15 K < T <= 2273.15 K       p <= 50 MPa

Regions

Figure 1 shows the five regions into which the entire range of validity of IAPWS-IF97 is divided.

 

Fig.1 Steam table regions defined in IAPWS-IF97

 
 
For more detailed information about the boundaries of the regions, and equations involved refer to "Release on the IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam" presented by The International Association for the Properties of Water and Steam .

Range of validity
Scientific Formulation (IAPWS-95)
 
The entire set of equations of IAPWS-95, used by the application for calculation of thermodynamic properties, is defined by the following temperature and pressure range:

• Melting / Sublimation curve <= T <= 5000 K       p <= 100000 MPa

Transport properties

 

Range of validity

Surface Tension

Equation for surface tension between liquid and vapor phase has range of validity from the triple point to the critical point:

• 273.16 <= T <= 647.096 K .

Viscosity of Ordinary Water Substance

Equations for dynamic and kinematic viscosity are valid in the range:

• 0 °C <= t <= 150 °C       p <= 500 MPa
• 150 °C < t <= 600 °C       p <= 350 MPa
• 600 °C < t <= 900 °C       p <= 300 MPa.

Thermal Conductivity of Ordinary Water Substance

Equations for thermal conductivity and thermal diffusivity are valid in the range:

• 0 °C <= t <= 500 °C       p <= 100 MPa
• 500 °C < t <= 650 °C       p <= 70 MPa
• 650 °C < t <= 800 °C       p <= 40 MPa.

Prandtl Number

Prandtl number depends on dynamic viscosity and thermal conductivity, so it has the range of validity according to these properties.

Input variables

Industrial Formulation IAPWS-IF97

To calculate properties of water and steam using IAPWS-IF97, Steam97Web allows up to 16 different combinations of input variables in SI or English units:

1. f (pressure, temperature)
2. f (pressure, enthalpy)
3. f (pressure, entropy)
4. f (pressure, specific volume)
5. f (pressure, internal energy)
6. f (temperature, enthalpy)
7. f (temperature, entropy)
8. f (temperature, specific volume)
9. f (temperature, internal energy)
10. f (enthalpy, entropy)
11. f (internal energy, entropy)
12. f (specific volume, entropy)
13. f (enthalpy, specific volumey)
14. f (internal energy, specific volume)
15. f (pressure, quality)
16. f (temperature, quality)

Range of validity for listed functions:

• Functions 1-14 are valid in all five regions defined by IAPWS-IF97.
• Functions 15 and 16 are valid in region 4 (saturation region) only.

Scientific Formulation IAPWS-95

To calculate properties of water and steam using IAPWS-95, Steam97Web allows up to 11 different combinations of input variables in SI or English units:

1. f (pressure, temperature)
2. f (pressure, enthalpy)
3. f (pressure, entropy)
4. f (pressure, specific volume)
5. f (pressure, internal energy)
6. f (temperature, enthalpy)
7. f (temperature, entropy)
8. f (temperature, specific volume)
9. f (temperature, internal energy)
10. f (pressure, quality)
11. f (temperature, quality)

Range of validity for listed functions:

• Functions 10 and 11 are valid in saturation region only.

Available properties

The following thermodynamic and transport properties can be calculated with Steam97Web:

1. Pressure, p
2. Temperature, t
3. Density, d
4. Specific Volume, v
5. Specific enthalpy, h
6. Specific entropy, s
7. Specific exergy, ex
8. Specific internal energy, u
9. Specific isobaric heat capacity, cp
10. Specific isochoric heat capacity, cv
11. Speed of sound, w
12. Isentropic exponent, kapa
13. Specific Helmholtz free energy, H
14. Specific Gibbs free energy, G
15. Compressibility factor, Z
16. Steam quality, x
17. Region (IAPWS-IF97 only), region
18. Isobaric volume expansion coefficient, alpha
19. Isothermal compressibility, Kt
20. Partial derivative (dV/dT)p, dvdt
21. Partial derivative (dV/dP)T, dvdp
22. Partial derivative (dP/dT)v, dpdt
23. Partial derivative (dP/dV)T, dpdv
24. Isothermal Joule-Thomson coefficient, iJTC
25. Joule-Thomson coefficient, JTC
26. Static dielectric constant (IAPWS-95 only), dc
27. Dynamic viscosity, dv
28. Kinematic viscosity, kv
29. Thermal conductivity, tc
30. Thermal diffusivity, td
31. Prandtl number, Pr
32. Surface tension, Sigma

Open new file

To open a new file, do the following:

1. Choose File, Open menu item.

This will clear all currently displayed data on the forms and diagrams.

Save data to Excel

To save calculated properties to your local computer, follow these steps:

1. Choose File, Save to Excel as CSV menu item. The File Download dialog appears;
2. Alternatively, choose File, Save to Excel as CSV Unicode menu item. The File Download dialog appears;
3. Choose Save to save the document to your computer.

The CSV Unicode format will save properly some special characters contained in the definition of units. Since CSV is just a text file you can open a saved file with any text editor, for example Notepad.

Select Units
 
In the "Units" group box, on the "Setup Pane", set units as required, SI and English units are available.

Select Formulation
 
In the "Formulation" group box, on the "Setup Pane", set desired formulation to use, Industrial (IAPWS-IF97) and Scientific (IAPWS-95) are available.

Ambient Condition
 
In the "Ambient" group box, on the "Setup Pane", set a reference temperature of the environment. The reference temperature will be used for the calculation of exergy.

Calculate Properties - Thermodynamic and Transport Properties of Water and Steam
 
At the top of the Steam Table Calculator Page there are two tabs, which enable you to select between "General properties" and "Saturation properties" of water and steam. On the first tab you can calculate water and steam properties in all regions, as defined by the application, including saturation properties. For example, if you enter input data that define a point inside the saturation region, properties will be calculated and displayed in the same way as properties for all other regions. On the other hand, on the second tab you will be able to calculate water and steam properties only in the saturation region.

Calculation procedure for all regions

In order to calculate water and steam properties valid in all regions, select the first tab "General properties", and use the following steps:

1. Choose units, SI or English.
2. Select one of the 14 different functions based on available input variables.
3. Enter data for the first parameter.
4. Enter data for the second parameter.
5. Press Calculate button to perform calculation.

Detailed result of a calculation is displayed in the main table, located in the lower part of the input form, and also 17 main properties are displayed in the "Output Pane". Input arguments used in a calculation are displayed in red. The last column "IAPWS" displays the formulation used for performing the calculation.

 

Click here for a larger image.

Fig.2 Calculation of general properties of water and steam

Calculation procedure for the saturation region
 
In order to calculate water and steam properties in the saturation region, select the second tab "Saturation properties", and use the following steps:

1. Choose units, SI or English.
2. Select one of the 2 different functions based on available input variables.
3. Enter data for the first parameter.
4. Enter data for the second parameter.
5. Press Calculate button to perform calculation.

Click here for a larger image.

Fig.3 Calculation of saturation properties of water and steam

In the Output Pane results are always inserted at the top, so you don't have to scroll to see the latest result.

Steam Turbine Calculations

Calculate steam consumption of a steam turbine
 
To calculate steam consumption of a steam turbine, follow these steps:

1. Select "Steam Turbine" tab;
2. In the "Select Calculator" group box select "Turbine steam consumption calculator" radio button;
3. Enter required input data in the "Input Data" group box;
4. Press "Calculate" button.

Results of the calculation will be displayed in the first empty "results" column in the main pane.


Calculate steam turbine efficiency
 
To calculate steam turbine efficiency, follow these steps:

1. Select "Steam Turbine" tab;
2. In the "Select Calculator" group box select "Turbine efficiency calculator" radio button;
3. Enter required input data in the "Input Data" group box;
4. Press "Calculate" button.

Results of the calculation will be displayed in the first empty "results" column in the main pane.


Calculate steam turbine power
 
To calculate steam turbine power, follow these steps:

1. Select "Steam Turbine" tab;
2. In the "Select Calculator" group box select "Turbine power calculator" radio button;
3. Enter required input data in the "Input Data" group box;
4. Press "Calculate" button.

Results of the calculation will be displayed in the first empty "results" column in the main pane.

Before making the fourth calculation, press the "Clear results" button to clear results from the 3 available result columns in the main pane.

For each steam turbine calculation, calculated inlet and exhaust conditions of the turbine will be displayed in the "Output pane" as well. To distinguish turbine results from other data, these rows will be displayed in green.

Flash evaporator calculations

Calculate flash evaporation of condensate at saturation
 
To calculate flash evaporation of condensate at saturation, follow these steps:

1. Select "Flash Evaporation" tab;
2. In the "Condensate" group box select "Condensate at saturation" radio button;
3. Enter required input data in the "Input Data" group box;
4. Press "Calculate" button.

Results of the calculation will be displayed in the first empty row in the main pane.


Calculate flash evaporation of subcooled condensate
 
To calculate flash evaporation of subcooled condensate, follow these steps:

1. Select "Flash Evaporation" tab;
2. In the "Condensate" group box select "Subcooled condensate" radio button;
3. Enter required input data in the "Input Data" group box;
4. Press "Calculate" button.

Results of the calculation will be displayed in the first empty row in the main pane.

For each flash evaporator calculation, calculated inlet and outlet conditions will be displayed in the "Output pane" as well. To distinguish flash evaporation results from other data, inlet properties will be displayed in blue and outlet properties in red.

Add Points

To display point(s) on Steam Table Mollier diagrams use the following steps:

1. Calculate a few points you want to display.
2. Click on the "Diagrams -> Add / Edit Points" menu item, the following dialog box should open.
3. If you work with SI units select the SI Units Tab radio button, otherwise select English units radio button.
4. In the "Displayed Point ID's" edit box type ID's of the points you want to display from the ID's column in the Output Pane, for example to display the first 3 points type: 1,2,3 .
5. In the "Point labels" edit box type the labels (of your choice) of the respective points, for example: a,b,c .
6. The number of points and the number of labels should match.
7. Press Save button and points will be displayed on all diagrams (Fig.5).
8. OPTIONALLY - You may open "Setup UI for Points" dialog box (Fig.4), by choosing "Diagrams->Setup UI for Points" menu item and change default radius and color of the points. This UI setup will be applied to all displayed points.

Edit Point(s)

To edit point(s) already displayed on the diagrams use the following steps:

1. Click on the "Diagrams -> Add / Edit Points" menu item to open "Add / Edit Points" dialog box.
2. In the "Displayed Point ID's" edit box make required changes.
3. In the "Point Labels" edit box make required changes.
4. Press Save button and modified points will be displayed on all diagrams.

Add a Line or a Curve

To display line(s) or curve(s) on the diagrams use the following steps:

Calculate and display a few points on the diagrams (see the Add Points section).









Edit box "Labels of currently displayed points" will show you available points for the creation of line(s) and curve(s).

1. Click on the "Diagrams -> Add a Line or a Curve" menu item to open "Add a Line or a Curve" dialog box.
2. In the edit box "Add labels to define a new series", add labels: a,b,c .
3. In the edit box "Add name of the series" type a name of a line/curve, for example: test .
4. In the "Set type of series" combo box select line or spline option. Spline is used to draw curves and you must provide at least 3 points to make it effective.
5. Press Save button and lines and curves will be displayed on all diagrams (Fig.8).
6. OPTIONALLY - You may open "Setup UI for Lines and Curves" dialog box (Fig.7), by choosing "Diagrams->Setup UI for Lines and Curves" menu item and change default width and color of the lines and curves. This UI setup will be applied to all displayed lines and curves.

Edit a Line or a Curve

To edit a line or a curve already displayed on the Steam Table diagrams use the following steps:

1. Click on the "Diagrams->Edit a Line or a Curve" menu item to open "Edit a Line or a Curve" dialog box.
2. In the combo box "Select a series to edit" choose a line or a curve you want to modify.
3. Make required changes to the currently selected line or curve.
4. Press the Save button to close the dialog box.

Save Diagram

To save a diagram use the following steps:

1. Click the right mouse button on a diagram.
2. On the context menu choose "Save Picture As..." menu option.

Print Diagram

To print a diagram use the following steps:

1. Resize the diagram by resizing the browser window and / or close the Output and Setup panes.
2. Click the right mouse button on a diagram.
3. On the context menu choose "Print Picture..." menu option.
4. Alternatively, use "File -> Print" option from the browsers menu (this should work the same in all browsers).
5. Or alternatively, save a diagram to your desktop and print it from one of available image handling applications.