Component Reference

Overview

This reference describes all component model types that can be used in plants. Each component represents a hydraulic element (pressure loss or pressure increase) and – depending on the type – a thermal model. The detailed descriptions are organized into subchapters by category:

Subchapter	Content
Pipes	Simple and discretized pipe, pressure loss according to Darcy-Weisbach
Pumps	Constant, linear and controlled head, pump characteristic curves, electrical power
Pressure losses & fittings	Controlled valve, pressure-loss elements, check valve, building-internal installation
Automatic sizing	Sized vs. individual variants of the consumer components
Simple heat exchanger	Simplified transfer-station model with demand boundary condition
Transfer station	Detailed counterflow model with limited transfer power
Model selection for consumers	Decision aid: heat exchanger or transfer station?
Ideal heat/cold generator	Supply temperature from the heating curve or prescribed heating power, power limits
Heat pumps	Source-side and supply-side heat pump with COP polynomial
Geothermal & heat sources	Borehole heat exchanger field, geothermal collector, source-side heat exchanger

Access

Components are dragged from the library onto the canvas in the graphical plant editor (accessed via Databases > Plants… and Edit plant …). Their parameters are edited there in the properties area of the respective component. For each component, the editor displays a detailed model description.

The heat exchange type is chosen per component in the Heat exchange tab. The possible types are: none (adiabatic), constant temperature, time-dependent temperature, constant heating power, time-dependent heating power – for details see heat exchange types.

Common model principles

Some parameters and relationships appear in almost all components:

Quadratic pressure loss law

The simple heat exchanger, transfer station, all heat pumps, the ideal heat/cold generator, the source-side heat exchanger and the element with quadratic pressure loss compute their pressure loss from a nominal operating point (nominal volume flow $\dot V_{nom}$ and nominal pressure loss $\Delta p_{nom}$). The pressure loss scales quadratically with the volume flow:

$\Delta p = \Delta p_{nom} \cdot \left( \frac{\dot V}{\dot V_{nom}} \right)^2$

For the sized variants, the nominal volume flow is determined automatically from the building’s connection load; only the nominal pressure loss then still has to be specified.

Other components follow their own laws: pipes, the borehole heat exchanger field, the geothermal collector and the building-internal installation use pipe friction (Darcy-Weisbach), the controlled valve uses its $K_{vs}$ value and a controller; the constant pressure loss element, zeta element, element with $K_{vs}$ value and check valve each have their own characteristics.

Fluid volume

The fluid volume of each component determines its thermal inertia: the contained fluid is balanced as an ideally mixed volume with a uniform temperature. Larger volumes dampen temperature changes and have a numerically stabilizing effect, but delay the response of the control.

The fluid volume is a fixed default per component type and cannot be edited in the component editor – e.g. 0.5 L for valves, 1 L for pumps and pressure-loss elements, 3 L for heat exchangers, transfer stations, heat pumps and source-side heat exchangers, and 5 L for the ideal heat/cold generator.

Parallel elements

Pipes and pumps have a counter for parallel elements (Number of parallel pipes or Number of parallel pumps). The mass flux is distributed evenly; pressure loss or head apply to each individual element.

Controller and heating curve requirements

Requirement	Components
Controller required	Pump with controlled head, controlled valve – see controller
Heating curve required	Transfer station (setpoint secondary side; not with constant demand), supply-side heat pump (supply setpoint), ideal heat/cold generator (supply temperature), source-side heat pump (condenser temperature)
Heating curve optional	Simple heat exchanger (limiting the outlet temperature)

The heating curve of a consumer is assigned via the building demand of the node. With a constant building demand the transfer station needs no heating curve; it then works with the constant heating setpoint and the constant temperature spread. For the supply-side heat pump and the ideal heat/cold generator, the heating curve is assigned in detailed plants directly to the component in the component editor; only in the simplified energy plant is it a plant setting.

Notes

• All default values are presets applied when creating a component and should be adjusted per project.
• All physical quantities are computed internally in SI base units; the reference tables state the display units of the user interface.

Related topics

• Plants: Concept
• Graphical plant editor
• Controller
• Heat exchange types