Editing Object Data

Work in Progress

The functionality described in this section contains information is still under development. Some information might be outdated, missing or not applicable anymore as it is not entirely adapted for usage with IPSE GO yet.

Most object data is entered directly into IPSE’s flowsheet via the data input dialog. The data input dialog is one of the most important windows in IPSE as it allows the user to specify data and relationships of objects in the flowsheet.

To open the data input dialog of an object:

Double click on the respective object on the object name in the object manager.
or
Right click on the object or the object name in the object manager to open the context menu and select the Edit command.

Figure 1 shows the data input window for a unit. If a unit contains more than one model to choose from, you can select it via the model selector in the data input dialog. Depending on the selected model, the elements displayed in the data input dialog may vary.

Figure 1. The data input dialog allows users to specify object data.

More detailed information about unit models and their different levels of complexity can be found in the documentation of the model library that you use.

Referencing Global Objects

If a unit or a connection contains references to one or more globals, its object data input dialog (see Figure 1) displays a section with the name of the reference just below the object name. In this section you can select the global object that you want to reference.

Frequently, several objects contain a reference to the same global object. Instead of defining the reference for each object separately, you can also define the reference for a group of objects.

Figure 2. Defining references to a global object

To define a reference to a global for a group of objects:

Select one or more objects in the project window.
Select Objects Set References. IPSE opens the window shown in Figure 2. In the left column, it displays all references to globals that are declared in at least one of the selected objects. At this point, the OK button is disabled since you have not yet chosen a valid selection.
Select the reference that you want to set. As soon as you select the reference, IPSE displays in the right column all the existing global objects that can be chosen. IPSE filters the global objects that cannot be selected due to their types.
Select the global object that you want to use in your references.
Accept your choice by clicking on OK, or by double clicking the selection.

The following elements are available to enter data for an object:

parameters
variables
tables
switches

Variables and Parameters

Parameters represent those values that are always required as input. Before system solution, IPSE checks whether all parameter values are given and prompts for the missing input.

Variables can either be prescribed to be settings or otherwise they are calculation results from the model equations. Some variables may be specified that they cannot be set. For such variables, the option set is not accessible. Such a specification can only be made by the developer of a model library to prevent the user from making unreasonable prescriptions.

To prescribe a variable:

In the data input dialog, select the option set right from the variable’s name and value.
Enter the numerical value that you want to prescribe for the variable.

For variables, you can also choose estimates as starting values and define limits. This improves the convergence characteristics and stability of a process model. See also the section Controlling Convergence.

To give an estimate for a variable:

Select the estimate option right from the variable’s name in the data input dialog.
Enter the numerical value that you want to use as an estimate for the variable when a calculation is started.

To define limits for a variable:

Click on the appropriate limit button in the object data input dialog.
Enter the minimum and maximal value for the variable.

Tables

Tables are used to hold characteristic curves that describe some model characteristics. The values that are entered in a table are very similar to parameters. You must always enter a sufficient number of values to define a characteristic curve.

Two types of tables are available:

2-dimensional tables, represented by X-Y-tables, see Figure 3.

Figure 3. The 2-dimensional table stores data in X-Y-tables.

3-dimensional tables, represented by X-Y-Z-tables, see Figure 4.

Figure 4. The 3-dimensional table stores data in X-Y-Z-tables.

To edit the data of a table:

In the object data input dialog click on the Edit button of the respective table. IPSE opens the table data window. Figure 3 shows the table data window for 2D-tables, Figure 4 the one for 3D-tables.
Enter the values into the different table cells.
Click on OK.

The table windows for editing 2D-Tables and 3D-Tables provide a menu bar which contains only one option called Edit. By using the commands of this option you can copy the table values from IPSE to the clipboard and paste table values from the clipboard to IPSE. Therefore a special clipboard format is used which will be described later in this section.

To copy table values to the clipboard:

Click on the command Copy of the option Edit from the menu bar of the window for editing table values (see Figure 3 for 2D-Tables and Figure 4 for 3D-Tables).

Using this command the complete table data will be copied to the clipboard.

To paste values from the clipboard to a table:

Click on the command Paste of the option Edit from the menu bar of the window for editing table values (see Figure 3 for 2D-Tables and Figure 4 for 3D-Tables).

If the data of the clipboard have the required clipboard format, the table will be filled with these data. If the data are not of this clipboard format, a message window will be displayed to inform you that the data cannot be inserted because of the wrong clipboard format.

The required clipboard format which is used for copying and pasting table values has the following characteristics:

A tabulator must exist between the values of two adjacent columns.
Every row of the table must be in a single line.
The last row must be an empty line.

If you are pasting values from the clipboard to a 2D-Table, the values of the first column correspond to the values of the left table column and the values of the second column correspond to the values of the right table column.

If you are pasting values from the clipboard to a 3D-Table, the values of the first column correspond to the first dimension values and the values of the first row correspond to the second dimension values. The value contained in the element at the intersection of the leftmost column and the uppermost row is not relevant since this value is only needed to ensure a rectangular matrix format but will not be inserted into the table.

All table data, for both 2 and 3 dimensional tables, must be sorted in increasing order. Furthermore, a 2D-table must contain the same number of x and y values. In a 3D-table, all columns must have the same number of variables. The same applies for the rows of a 3D-table. However, the number of variables of the rows may differ from the number of variables of the columns.

When IPSE evaluates a table, it interpolates between the given data points. IPSE provides two different interpolation methods:

linear interpolation for 2D- and 3D-tables
cubic splines interpolation for 2D-tables and bicubic spline interpolation for 3D-tables
To choose the interpolation method:
Open the object data input window.

Open the window for editing the table data by clicking on Edit>>.

Choose the appropriate interpolation method.

Click on OK.

Linear interpolation is selected by default.

If it is necessary to extrapolate the values in a table, IPSE extrapolates them always linearly. If the spline option is selected for interpolation, the tangent of the spline at the closest given point is used for the linear extrapolation if necessary. In case that a table is extrapolated during system solution, IPSE issues a warning.

Switches

Switches are used to select different variants for a model. Usually, switches allow you to determine the equations of the model that are in use and thereby to change the behavior of the model.

Switches define which equations are used by a model. A changed switch may also mean a change in the number of model equations. As a consequence, it might be necessary to provide additional setting or to remove existing ones.

Editing Data for Global Objects

Unlike units and connections, global objects do not have a graphic icon which you can double click for editing. If you want to edit a global object, you must open the data window for this object via the object bar or via the menu.

To open the data input window of a global object:

Select the object in the object list of the object bar.
Click on the Edit Object icon illustrated here. IPSE opens the window for editing the chosen global object data.

Select Object Edit Global Object. IPSE opens a window with a list of all available global objects.
Select the global object, that you want to edit.
Click on OK or double click on the selected global object. IPSE opens the window for editing the global object data.

See also the previous description about editing data of a unit or connection.

Deleting a Global Object

To delete a global object:

Select Object Delete Global Object. IPSE displays the window shown in Figure 5.
Select from the left list the global object that you want to delete by clicking on it.
Click on Remove. The selected global will then be transferred to the list of objects to be deleted. Repeat this action for each global object that you want to delete.
Click on OK to delete all objects in the delete list.

Figure 5. Dialog for deleting global objects