About NH3 Calculator

Thermodynamic and Transport Properties of Ammonia


The NH3 Calculator Web application calculates 29 thermodynamic and transport properties of ammonia. It allows 11 different combinations of input variables to be used in calculations. Input variables that can be used are: pressure, temperature, enthalpy, entropy, volume, internal energy and quality (vapor mass fraction).


For thermodynamic properties the application uses new industrial formulation for ammonia, formulated in Helmholtz energy. It is intended to be used for advanced technical applications. Equation of state was presented in "Equations of State for Technical Applications" by R. Span and W. Wagner, International Journal of Thermophysics, Vol.24, No.1, January 2003. For transport properties the library uses equations presented in: "The Viscosity of Ammonia" by A. Fenghour, W. A. Wakeham, V. Vesovic, J.T.R.Watson, J. Millat, E.Vogel; and "Equations for Thermal Conductivity of Natural Refrigerants" by J. Yata, M. Hori, Y. Isono, and Y. Ueda.

Thermodynamic properties

Range of validity

The entire set of equations used by the NH3 Calculator Web application for calculation of thermodynamic properties, is defined by the following temperature and pressure range:

• 195.5 K <= T <= 574 K
• 0 <= p <= 85 MPa.

Transport properties

Range of validity

Viscosity of Ammonia

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

• 195.5 K <= T <= 574 K
• 0 <= p <= 50 Pa.

Thermal Conductivity of Ammonia

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

• 195.5 K <= T <= 574 K
• 0 <= p <= 50 MPa.

Prandtl Number

Prandtl number is dependent of dynamic viscosity and thermal conductivity, so it has range of validity according to these properties.

Reference State

According to the standards in refrigeration engineering, the integration constants in the formulations for ammonia were chosen in such a way that (for the part of formulation which describes ideal gas) h' = 200 kJ/kg and s' = 1 kJ/(kg·K) for the saturated liquid at T0=273.15 K.

Input variables

To calculate properties, NH3 Calculator 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 1-9 are valid in all regions defined by the application.
• Functions 10 and 11 are valid in saturation region only.

Available Properties

The following thermodynamic and transport properties can be calculated with NH3 Calculator:

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. Quality [vapor mass fraction], x
17. Isobaric volume expansion coefficient, alpha
18. Isothermal compressibility, Kt
19. Partial derivative (dV/dT)p, dvdt
20. Partial derivative (dV/dP)T, dvdp
21. Partial derivative (dP/dT)v, dpdt
22. Partial derivative (dP/dV)T, dpdv
23. Isothermal Joule-Thomson coefficient, iJTC
24. Joule-Thomson coefficient, JTC
25. Melting pressure, pm
26. Dynamic viscosity, dv
27. Kinematic viscosity, kv
28. Thermal conductivity, tc
29. Thermal diffusivity, td
30. Prandtl number, Pr

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.

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.

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

Calculate Properties
 
At the top of the NH3 Table Calculator Page the first two tabs enable you to select between "General properties" and "Saturation properties". On the "General Properties" tab you will be able to calculate 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 properties only in saturation region.
 

Calculation procedure for all regions
 
In order to calculate properties valid in all regions, select the first tab "General properties", and follow next steps:

1. Choose units, SI or English.
2. Select one of the 9 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 12 main properties are displayed in the "Output pane". Input arguments used in a calculation are displayed in red.
 

 

Click here for a larger image.

Fig.1 Calculation of General properties of ammonia

Calculation procedure for the saturation region

In order to calculate properties in the saturation region, select the second tab "Saturation properties", and follow next 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.2 Calculation of Saturation properties of ammonia

Ammonia turbine calculations

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

1. Select "Ammonia 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 ammonia turbine efficiency

To calculate ammmonia turbine efficiency, follow these steps:

1. Select "Ammonia 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 ammonia turbine power

To calculate ammonia turbine power, follow these steps:

1. Select "Ammonia 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 ammonia 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 NH3 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. OPTIONALY - 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. OPTIONALY - 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 NH3 diagrams use the following steps:

1. Click on the "Diagrams->Edit a Lines 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, save a diagram to your desktop and print it from one of available image handling applications.