modelHeatflow_L1
Extends from TransiEnt.Components.Boundaries.Heat.Base.PartialHeatBoundary.
Information
Purpose of model
An ideal boundary model with prescribed or constant heat flow and without a fluid volume. Pressure loss is constant and given via a parameter. A static mass, momentum and energy balance is assumed. The outlet temperature can be limited if needed.
Level of detail, physical effects considered, and physical insight
L1 (Defined in Coding Conventions)
- Constant pressure loss
- no fluid volume (no dynamics are considered)
Limits of validity
No dynamics are considered
Interfaces
FluidPortIn: for the connection with a hydraulic grid
FluidPortOut: for the connection with a hydraulic grid
RealInput: Q_flow_prescribed (for specification of boundary heat flow rate)
RealInput: T_out_limit_prescribed (for limiting the outlet temperature)
Governing Equations
Mass balance: fluidPortIn.m_flow + fluidPortOut.m_flow = 0
Momentum balance: - fluidPortOut.p + fluidPortIn.p = p_drop
h = Q_flow_internal/fluidPortOut.m_flow
Remarks for Usage
Heat flow can be limited by T_out_limit if use_T_out_limit==true to model a temperature level of heat source/heat sink
This boundary does not define a mass flow rate or a pressure. The use of the model is shown in the test model: TransiEnt.Components.Boundaries.Heat.Check.testHeatflow_L1
Validation
Tested in model TransiEnt.Components.Boundaries.Heat.Check.testHeatflow_L1
Seems that no further testing is necessary because of simplicity of component
Version History
Model created by Pascal Dubucq (dubucq@tuhh.de) on Mon Aug 18 2014
Model modified by Oliver Schülting (oliver.schuelting@tuhh.de) on Jul 2019
Documentation modified by Jan Westphal (j.westphal@tuhh.de) August 2025
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| TILMedia.VLEFluidTypes.BaseVLEFluid | Medium (from PartialHeatBoundary) | simCenter.fluid1 | Medium model |
| SI.Power | Q_flow_const | 100e3 | Constant heating Power |
| Boolean | use_Q_flow_in | true | Use external Value for Q_flow |
| Boolean | use_T_out_limit | false | Use limitation of output temperature |
| SI.Pressure | p_drop | simCenter.p_nom[2] - simCenter.p_nom[1] | Nominal pressure drop |
| Boolean | change_sign | false | Change sign on input values, false: negative setpoint will produce heat |
| SI.Temperature | T_out_limit_const | 273.15 + 100 | maximum output temperature - if change_sign==true: minimum output temperature |
| Boolean | useVariableToutlimit | false | Define limit of output muss flow by input |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.Basics.Interfaces.Thermal.FluidPortOut | fluidPortOut (from PartialHeatBoundary) | ||
| TransiEnt.Basics.Interfaces.Thermal.FluidPortIn | fluidPortIn (from PartialHeatBoundary) | ||
| TransiEnt.Basics.Interfaces.Thermal.HeatFlowRateIn | Q_flow_prescribed | RealInput (for specification of boundary power) | |
| TransiEnt.Basics.Interfaces.General.TemperatureIn | T_out_limit_prescribed |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| TransiEnt.SimCenter | simCenter (from PartialHeatBoundary) | ||
| Modelica.Units.SI.HeatFlowRate | Q_flow_boundary (from PartialHeatBoundary) | fluidPortIn.m_flow*(actualStream(fluidPortIn.h_outflow) - actualStream(fluidPortOut.h_outflow)) | |
| SI.SpecificEnthalpy | h | ||
| SI.SpecificEnthalpy | h_out_limit |