modelJunction
Information
Purpose of model
A model of a split/join that is used to split or join mass flow rates in a hydraulic circuit. It is based on the three balance equations of mass, energy, and momentum. It is not discretized and only features one control volume. No heat losses and no pressure losses are considered. The model is mainly used for the simulation of district heating networks.
The model is used as a junction in district heating networks and dwelling heat systems. It contains n-ports. The number of ports can be set by the user.
Level of detail, physical effects considered, and physical insight
L2 (defined in the CodingConventions)
- No pressure losses considered
- Consideration of thermal inertia
- Constant fluid properties
- Static mass balance
Limits of validity
The volume of the split has to be known.
Interfaces
Governing Equations
The equations have been simplified for an easier description of the model.
V*rho*dh/dt=m_in*h_in+m_out1*h_out1+m_out2*h_out2
0=m_flow_in+m_flow_out1+m_flow_out2
References
The model was used in the following publication:
[1]Vieth, J.; Westphal, J.; Speerforck, A.; District heating network topology optimization and optimal co-planning using dynamic simulations; Advances in Applied Energy; 2025
Version History
Model was inserted by Jan Westphal (j.westphal@tuhh.de) August 2025
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Integer | n_ports | 3 | number of edges this junction is connected to |
| SI.MassFlowRate | m_flow_nom | 1 | Nominal mass flow rate of the water |
| SI.PressureDifference | delta_p_nom | 0.1e1 | Nominal pressure drop in the junction |
| SI.Volume | V | 0.005 | Volume of the junction |
| SI.Density | rho | 983 | Density of the water |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.Basics.Interfaces.Thermal.FluidPortIn_simple[n_ports] | fluidPort |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| SI.SpecificEnthalpy | h | ||
| SI.Pressure | p |