Thermodynamic Database Editor

Thermodynamic Database Editor is an embedded species viewer/editor. Using the tool, you can easily define new propellant components, or import components from PROPEP or CEA2 species databases.

RPA distribution packages contain two database files resources/thermo.inp and resources/properties.inp. The file resources/thermo.inp contains the thernodynamic properties in format described in reference http://www.grc.nasa.gov/WWW/CEAWeb/def_formats.htm.

You can define your own species and save it into two additional database files resources/usr_thermo.inp and resources/usr_properties.inp. These files are not shipped within standard RPA distribution packages, and will not be rewritten after program update.

The tool consists of database viewer at the top of the screen, and species editor at the bottom. You can shrink or heighten the species viewer while the species editor will be heightened or shrunk, dragging the horizontal bar between the viewer and the editor down or up.

Thermodynamic Database Editor

The viewer features the species table, filter and the control buttons. Species table displays currently available species with respect to the filter settings:

You can force the viewer to display the fuels only, or oxidizers only, or both fuels and oxidizers, marking corresponding radio buttons. Mark the checkbox "All species" if you want to see all species, including atomized and/or ionized products of reaction, or keep it unmarked if you want to see only possible propellant components.

The filter pattern is applied to both columns of the table.

The control buttons can be used as follows:

• Click the button Reload to reload the default database. Any changes made since the database was last saved will be lost.
• Click the button Save to save the changes made since the database was last saved. The program creates a backup-copy of previous version of the database files, adding the character "~" to the name of the file.
• Click the button Save As... to save the current database in specified location.
• Click the button Import to import the species from external database file in CEA2 or PROPEP formats. After successful loading the external database, the program displays the list of available species is the dialog window. Select one or more species that you want to import and click the button OK. All imported species are immediately available for thermodynamic analysis.
• Click the button Edit to load the data of the selected species into the species editor. You can also double click the species on the list to load it into the editor.
• Click the button Remove to remove the species from the current database. Note that removed species are immediately unavailable for thermodynamic analysis.
• Click the button New to reset the editor for creating a new species.

Note: all new species are saved into the user-defined database files resources/usr_thermo.inp and resources/usr_properties.inp.

Note: although you can import any component from PROPEP specues database, do not replace all components already available in CEA2/RPA database: the sources of the data in CEA2 file are NASA Glen thermodynamic database and Gurvich thermodynamic database, both known for their high accuracy.

Note: since PROPEP library does not contain the component's temperature, always check standard temperature and tabular data for imported components.

Note: always check the log (click item Run in main menu, and then Show log; check the tabs "Warnings" and/or "Errors") just after the import from PROPEP library.

The editor consists of three tabs Component, Polynomial properties, and Tabular properties, and the control buttons at the bottom of the editor:

To save the changed in existing species or save new species, click the button Update. To reset the species data, click the button Reset.

The tab Component displays the information about component, its aggregate state, chemical formula, molecular weight, heat of formation, and the temperature the heat of formation is defined for.

The component name is also an identifier of the species and must be unique within the database. The suffix (L) can be added to the end of the name for the liquid components.

The description usually contains common name of the species, as well as the reference information.

The chemical formula is given as a molecular formula (if applicable), or a brutto formula, followed by its molecular weight. The heat of formation (enthalpy) can be given in one one the units: J/mol, cal/mol, kJ/kg, kcal/kg, Btu/lbm, kcal/lbm. The heat of formation is followed by the temperature (given in one of the units: K, R, C, F), for which it has been defined. Note that if polynomial properties are available, the temperature is always 298.15 K and cannot be changed.

Polynomial properties for the one or more temperature interval are given by 9 coefficients as described in reference http://www.grc.nasa.gov/WWW/CEAWeb/def_formats.htm. Click the button Add to add new temperature interval; click the button Remove to delete selected temperature interval.

Tabular properties for the one or more pressure and temperature intervals are given by values of specific heat Cp (kJ/mol-K), density rho (kg/m3) and dynamic viscosity mu (muPa-s) for each unique combination of pressure and temperature. Click the button Add p to add new pressure interval; click the button Remove p to delete selected pressure interval. Click the button Add T to add new temperature interval; click the button Remove T to delete selected temperature interval.

Note: For the components which are supplied together with thermodynamic properties in the polynomial form, you do not need to define the specific heat (define "0" instead).

Note: For the gaseous components you do not need to define the density.

In the database file, the tabular data are formatted as follows:

!p, MPa       T, K          Cp, kJ/mol-K  rho, kg/m3    mu, muPa-s
Comp_name         2,3
p1            T1            Cp11          rho11         mu11
p1            T2            Cp12          rho12         mu12
p1            T3            Cp13          rho13         mu13
p2            T1            Cp21          rho21         mu21
p2            T2            Cp22          rho22         mu22
p2            T3            Cp23          rho23         mu23

The minimalist data for the component consists of at least two rows:

!p, MPa       T, K          Cp, kJ/mol-K  rho, kg/m3    mu, muPa-s
Comp_name         1,2
 0.101325     273.15        0.078         823.0
 0.101325     373.15        0.078         823.0

This data defines the constant specific heat Cp and constant density rho, and allows to specify the initial temperature in the range 273.15-373.15 K as well as the initial pressure in the range 0...(the-max-pressure-you-need). Viscosity is not defined (as it will only be required by RPA Standard Edition) and assumed to be equal 0.

Last modified: May 18, 2011