© 2021 Jasper van Baten, AmsterCHEM

Parameters

The Excel unit operation supports in- and output parameters. Currently, only scalar numeric parameters are supported. The input parameters are defined on the input parameters sheet, and the output parameters are defined on the output parameters sheet.

Input parameters

Like with the ports, you can add and remove input parameters by adding names to the table. Make sure that header row 1 remains unmodified, and that there are no empty lines between parameters.

In addition to specifying the parameter name, you can specify an initial value. Next, you may want to define a minimum or maximum value. Setting a minimum or maximum value will prevent the simulation environment from specifying a value outside of the valid range. Minimum and maximum values are optional, leave blank in case they do not apply.

For each parameter you can also specify the unit of measure. All unit of measures are in SI. The SI base units are listed, and entering a unit of measure is a matter of filling in the non-zero numbers where required (zeroes do not have to be filled in). For example, the unit for pressure is Pa = N / m2 = kg m / s2 / m2 = kg / m / s2. So enter a 1 in the column for kg, -1 for m and -2 for s.

To simplify adding an input parameter, you can select Add Input Parameter Add Input Parameter from the Unit Operation ribbon. This will show a dialog in which the parameter name, initial value, minimum and maximum values can be specified. You can also type the SI unit of measure for the parameter here; the SI base units and their powers will be derived. You can also specify an Excel range name for the parameter' value, which you can refer to in formulas.

Additionally, for relative values one should put a 1 in the column marked delta. So an absolute pressure should not have a 1 in this column, but a pressure difference (e.g. a pressure drop) should. Simulation environments that support this type of unit of measure will know not to apply an offset to the unit conversions if the delta flag is set. E.g. conversion from °C to K is T/[°C] = 1.0 T/[K] + 273.15 for absolute temperatures, but T/[°C] = 1.0 T/[K] for relative temperatures, e.g. temperature differences.

Output parameters

The output parameters sheet has the same format of the input parameters sheet. You can add or remove parameters by changing the parameter table. Keep header row 1 unmodified, and make sure no empty lines appear between parameter definitions.

Output parameters cannot be set by the simulation environment. Specifying a minimum or maximum value is therefore not very useful.

To simplify adding an input parameter, you can select Add Output Parameter Add Output Parameter from the Unit Operation ribbon. This will show a dialog in which the parameter name can be specified. You can also type the SI unit of measure for the parameter here; the SI base units and their powers will be derived.

Enter an Excel formula to calculate the value of each output parameter. It is advised not to make complex calculations on the output parameters sheet, but rather on another sheet, e.g. the calculations sheet.

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CONTENT
 Introduction
 Ports and streams
 Parameters
 Function reference
 The control sheet
 Using the Excel solver
 Using Macros
 Loading and storing models
 Persistence in AspenPlus
 Examples
 Disclaimer