Defining Outputs
Define default and custom outputs of the dynamic simulation: result quantities, file format and output grid
Overview
On the Outputs page, you define which result quantities the dynamic simulation writes, in which temporal grid (output grid) and in which file format. In most projects, the defaults are sufficient: the network-related default outputs automatically provide all quantities that the integrated result display needs. Additional quantities – such as the Reynolds number of a pipe or the manipulated variable of a controller – can be added as custom outputs when required.
Access
Simulation button in the main toolbar, then the Outputs page in the list on the left.
Default Outputs
The option Generate default network-related outputs is enabled by default for heat network projects and automatically creates output definitions for all elements of the simulated network at the start of the simulation:
- Element quantities: mass flux, volume flow, flow velocity, temperatures and pressures at inlet and outlet, pressure and temperature difference, heat losses, heating and electrical powers, COP, head and more – which quantities an element provides depends on the component type (for the complete list see Model Representation and Result Quantities).
- Sum outputs: In addition, the summed heat flux (HeatLossSum) is written as a mean value per output step – per component (e.g. all transfer stations of one type) as well as for all supply pipes, all return pipes and all pipes together.
The default outputs are written hourly – they always use the first output grid in the list (the default grid hourly).
The default outputs are a prerequisite for the integrated result display (false color, line charts, summary). Only disable the option if you want to define all outputs manually.
Output Format
The option Use binary format (enabled by default) determines the file format of the result files in the <ProjectName>/results/ folder:
| Format | File extension | Properties |
|---|---|---|
| Binary format | .btf | Faster to write and read, significantly smaller files – noticeable with large networks and fine output grids |
| Text format | .tsv | Tab-separated text file, directly readable in a text editor, Excel or Python |
The integrated result display and the external PostProc application read both formats. The text format is worthwhile if you want to further process the files with your own tools (see Evaluation and Export).
Output Grid
An output grid defines the points in time at which results are written – independently of the time steps used internally by the solver. The Output Grids table shows all grids of the project with the columns Name, Intervals, Start and End.
The first row is always the default grid hourly (start at 0, step size 1 h, up to end of the simulation). It is shown in gray and can neither be edited nor deleted.
You manage your own grids via the buttons to the right of the table:
| Button | Function |
|---|---|
| + | Create a new output grid |
| … | Edit the selected grid |
| − | Delete the selected grid |
In the editor dialog, you assign a unique name (the name hourly is reserved) and define one or more consecutive time sections via Number of intervals. For each interval, you specify start time, end time and step length, each with a time unit (e.g. 0 d, 1 h, 30 min):
- The start time counts from the beginning of the simulation and is mandatory; the intervals must not overlap.
- The end time is optional – if it is left empty in the last interval, the grid runs until the end of the simulation.
- The step length is the spacing of the output points in time within the interval.
Example for a 2-year simulation with a fine evaluation in the second year: interval 1 with start time 0 a and step length 1 d, interval 2 with start time 1 a and step length 1 h.
Custom outputs can use any grid in the list; the automatically generated default outputs always use the first grid. Result files on a grid other than hourly receive its name as a suffix in the file name.
Custom Outputs
The collapsible Custom Outputs area adds individual result quantities that go beyond the default outputs. The workflow:
- Update output list: Performs a test initialization of the model and creates the file
<ProjectName>/var/output_reference_list.txtwith all quantities available in the current model. If the project is newer than this list, the note “The output definition list is outdated, you should update the output list.” appears. - Select a quantity in the Available Outputs table. The table shows the keyword, unit and description of each quantity; filtering is done via the object-type buttons (e.g. All, Network element, Model, Location) as well as the Name filter: and Unit filter: fields.
- Select objects: With the option Write outputs for all objects enabled (default), the output applies to all objects of the type. If you disable the option, the Objects and, where applicable, Vector indices lists appear, in which you specify individual network elements via multiple selection.
- With + or a double-click on the row, the definition is transferred into the Defined Outputs table.
The Defined Outputs table lists all custom outputs with quantity, object type, object IDs, vector IDs, time type (Mean/Integral) and output grid. The last two columns are editable directly in the table:
| Time type | Meaning |
|---|---|
| None | Instantaneous value at the output point in time |
| Mean | Mean value over the last output step |
| Integral | Cumulative time integral since the start of the simulation – this turns a power into a summed energy quantity |
On adding, the time type is preset automatically: power quantities (unit W) receive Mean, all others None. Averaged and integrated outputs receive the suffix -mean or -integral in the file name.
Definitions that are no longer available in the current model – e.g. after deleting a network element – are shown in red and italic; the tooltip states the cause (e.g. “No such object ID”). In that case, update the output list and remove orphaned definitions with −.
Practical tip:
If you need energy quantities directly from a power – such as monthly balances of the injected heat – combine a custom output grid with the time type Integral: a grid with step length 30 d and the heating power as an integral deliver the summed energy quantity at each month’s end. The last value of the file is the annual energy, and the monthly values follow as the difference of adjacent rows – summing up hourly time series is no longer needed. Side effect: the file stays tiny – twelve values instead of 8760.