Use this window to regress data to generate thermodynamic method interaction parameters, to fit data to property correlations or to determine parameters for Redlich-Kister Heat of Mixing.
The Regression ID, Description and the Regression Specification details are shown for information. This information is entered or modified in the Data Regression General Definition Window which is opened by pushing the Modify button.
The data to be regressed are entered in the Property Correlation Data Window or the Equilibrium Data Window which is opened by pushing the Enter Data button.
Press the Objective Function button to open the Objective Function Window where you define the objective function and the convergence control parameters.
Press the Print Options button to open the Print Options Window where you specify the amount of intermediate output.
If regressing onto a physical property equation, pushing the View Equation button brings up a window which shows the selected equation.
After the regression has been specified, the appropriate information will be entered into the Component and Parameters columns of the table. Initial Estimates are required for all these Parameters. You may either enter a value directly or you may press the Generate Initial Estimates button to create values.
If you do nat want the value of an estimate to be changed during the reconciliation (i.e. you know that it is the correct value), click on the Not Fixed text and it will change to Fixed.
After the calculation, the Calculated Values for all the Parameters are entered and you can compare with your estimates.
Pushing this button transfers the initial estimate values into the Calculated Values column. You may then press the View Results button to view the fit to the correlation using the initial estimates. You can compare the calculated values with the input data values that you entered. This will indicate if the estimates are close to the correct values.
Push this button to open the Initial Estimates Window where you specify the method for creating the Initial Estimates and supply any required data.
When all the required data have been supplied, the Run Regression button becomes available. Press this button to perform the regression calculations.
After the calculation, you may preview the results in tabular or graphical form in the View Results Window by pushing the View Results button.
If the results are satisfactory, push the Store Results button to transfer the results to the simulation database files, just as if you had entered them directly on the flowsheet.
How to get to this window
The PRO/II - Data Regression window is accessed by selecting Data Regression from the Input Menu.