Model inputs and calculated quantities
An equipment symbol identifies a unit operation. Its mathematical model defines the inputs it requires and the results it can produce.
A symbol does not define the complete model
The equipment icon locates a unit operation in the flowsheet, while the selected mathematical model describes how it transforms or separates material. Two models represented by similar screen or crusher symbols may require different input data and have different assumptions.
Selecting an item establishes which equipment the Inspector Panel describes. The label and tabs are therefore part of the context for every displayed number. A parameter value has no complete meaning without knowing which model and equipment it belongs to.
A supplied value is an assumption in the calculation
Model Parameters contains the inputs supplied to the selected equipment model. The parameter’s physical meaning and unit determine what a number represents. A coefficient that is meaningful in one model cannot be transferred to another merely because their parameter names look similar.
For a study to be understandable later, the origin of an input matters alongside its magnitude. A specified setting, an estimate and a calibrated coefficient can all be supplied inputs, but they support different conclusions about the model’s relation to a real plant. The model reference gives the equations and assumptions needed to interpret each parameter.
The basis of a value includes more than its number
A unit change can alter the physical input unless the value is converted. For example, 500 µm and 0.5 mm describe the same size; 500 entered as millimetres does not. The unit displayed by the selected model is therefore part of the input definition.
Some model entries also apply to a particular component or particle-size class. The component definition and size mesh determine the meaning of those entries. After either project definition changes, model-dependent parameter structures need review before another calculation.
| Question about an input | Why the answer matters |
|---|---|
| Which physical or mathematical quantity is it? | Its meaning follows from the selected model and its assumptions. |
| Which unit, phase, component or size class applies? | The basis determines how the number is used and compared. |
| Where did the value come from? | Measured, specified, estimated, assumed and calibrated values carry different evidence. |
A calculated value answers a different question
After the static calculation, Calculated Parameters contains Value (SIM) results provided by the selected model. These describe what followed from the supplied inputs and connected material; they are not a second set of direct inputs for adjustment.
| View | Role in the study |
|---|---|
| Model Parameters · Value (EXP) | Assumptions and inputs supplied to the equipment model. |
| Calculated Parameters · Value (SIM) | Outputs produced by that model after calculation. |
| Detailed Output | Additional model-specific information, when available. |
The available outputs vary by model. A limited output list does not mean that every model should supply identical diagnostics. Comparing results requires the same quantity definition and engineering basis, rather than relying on a similar position in two tables.
An input change creates a comparison only after recalculation
Changing an input changes the description of the process. It does not immediately establish a new downstream result. The connected flowsheet must be recalculated so that the changed assumption can affect the material passing through its models.
A separate base case makes the comparison traceable. With feed conditions, model selection and the other inputs held fixed, a change to one justified parameter can be related to the difference in results. If several assumptions change together, a different product value alone does not explain which assumption caused it.
Exercise: trace one input into a calculated result
- In the saved circuit, select the equipment and identify its model, label and one relevant input. Read the parameter’s meaning and unit in the model reference.
- Record the base-case value and its source. Use the equipment panel’s Edit control and change that input in Value (EXP), using a value justified for the model. Keep the other study assumptions identifiable.
- Run the static calculation again. Compare the same feed and product streams with the base case, using the same quantity definitions and units.
- Distinguish the input you changed from the calculated parameters and stream outputs that responded. If the result is unexpected, revisit the model assumptions, connections and component/size basis before changing more inputs.