Select the logarithm basis for a temperature-dependent property correlation

When you override temperature-dependent property data, you can use the LogType list on the Temperature Dependent tab to select the logarithm basis that you want to use for the logarithms in the temperature-dependent property correlation. If the correlation that you have selected in the Correlation list does not include a logarithm in the main calculations, the LogType value is NA, and you cannot change this value. If the correlation includes a logarithm, you can:

• Set the LogType to Ln to use natural logarithms.

• Set the LogType to Log to use base-10 logarithms.

The Ln and Log options correspond to the same selections in the Log Basis list on the TempDep tab in AVEVA Thermodynamic Data Manager.

As with other thermodynamic data overrides, changes that you make to the LogType in the Fluid Editor do not propagate to any thermodynamic libraries in AVEVA Thermodynamic Data Manager. If you plan to make similar changes to multiple Fluid Types, you may want to update your thermodynamic libraries in AVEVA Thermodynamic Data Manager instead.

The following correlations support changing the logarithm basis:

• Correlation 12

• Correlation 14

• Correlation 20

• Correlation 21

• Correlation 22

• Correlation 28

• Correlation 37

• Correlation 38

• Correlation 44

• Correlation 47

• Correlation 48

See Equation forms for temperature-dependent properties in AVEVA Thermodynamic Data Manager for more information on the individual correlations.

Select the logarithm basis for a temperature-dependent property correlation

1. In the Fluid Editor, expand the Component Data section, and then select the Temperature Dependent tab.

2. In the temperature-dependent property list, select the property whose data you want to change.

   The property data for each component appears in the table on the Temperature Dependent tab.

3. In the table, in the LogType list for the desired component, select one of the following:

   • Ln – Use natural logarithms.

   • Log – Use base-10 logarithms.

   If the LogType is NA, then the selected correlation in the Correlation list does not support changing the logarithm basis, and you cannot change the LogType value.

4. Update the constant coefficients for the correlation (c1 through c10) as needed to match the selected logarithm basis.