modelHeatExchanger
Information
Purpose of model
A model of a heat exchanger. It consists of two fluid ports and a heat port. The model is based on the three balance equations of mass, energy and momentum. A dynamic energy balance is assumed. The mass and momentum balance are assumed to be static. No pressure losses are considered. The heat flow is calculated with an equation based on EN442.
It is used for the modeling of radiators and the modeling of substations in district heating networks.
Level of detail, physical effects considered, and physical insight
L2 (defined in the CodingConventions)
- no pressure losses considered
- static mass balance
- constant fluid properties
- dynamic energy balance
- heat transport according to EN442
Interfaces
inlet: A fluid inlet for the inflowing heat carrier medium
outlet: A fluid outlet for the outflowing heat carrier medium
heatPort: A heat port for transporting the heat from the heat carrier
Governing Equations
Mass balance: m_in+m_out=0
Energy balance: V*rho*dh/dt=m_in*h_in+m_out*h_in-Q_flow
Heat transport: Q_flow = Q_flow_nom * (abs(heatPort.T - T_out) / delta_T_nom) ^ n
References
The model was used and verified in this publication:
[1] Westphal, J.; Brunnemann, J.; Speerforck, A.; Enabling the dynamic simulation of an unaggregated, meshed district heating network with several thousand substations;Energy; 2025
Moreover it was also used here:
[2]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) January 2025
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| SI.MassFlowRate | m_flow_nom | 1 | Nominal mass flow rate of the water |
| SI.PressureDifference | delta_p_nom | 0.02e3 | Pressure drop in the heat exchanger (Unused) |
| SI.Volume | V | 0.5 | Volume of the heat exchanger |
| SI.Density | rho | 983 | Density of the water |
| SI.TemperatureDifference | delta_T_nom | 8 | Nominal temperature difference between supply and return temperature8 |
| SI.HeatFlowRate | Q_flow_nom | 4e3 | Nominal heat flow rate at a given temperature difference |
| Real | n | 1.333 | Exponent for radiators |
| SI.SpecificHeatCapacity | cp | 4186 | Specific heat capacity |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.Basics.Interfaces.Thermal.FluidPortIn_simple | inlet | ||
| TransiEnt.Basics.Interfaces.Thermal.FluidPortOut_simple | outlet | ||
| Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_a | heatPort |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| SI.MassFlowRate | m_flow | ||
| SI.SpecificEnthalpy | h | ||
| SI.HeatFlowRate | Q_flow | ||
| SI.Temperature | T_in | ||
| SI.Temperature | T_out |