modelPlugFlowULg
Extends from Modelica.Icons.Example (Icon for runnable examples).
Information
The example contains experimental data from a real district heating network.
This model compares the results with the original Modelica Standard Library pipes.
The pipes' temperatures are not initialized. Therefore, results of outflow temperature before approximately the first 10000 seconds should not be considered.
Test bench schematic
Calibration
There are some uncertainties about the heat loss coefficient between pipe and
surrounding air as well as regarding the heat conductivity of the insulation
material.
With the
given data, the length specific thermal resistance is R = 2.164
((m K)/W), calculated as follows:
R=((1/(2*pipe.kIns)*log((0.0603+2*pipe.dIns)/(0.0603)))+1/(5*(0.0603+2*pipe.dIns)))/Modelica.Constants.pi
U = 1/R = 0.462 W/(m K)
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.MassFlowRate | m_flow_nominal | 1 | Nominal mass flow rate, used for regularization near zero flow |
| Modelica.Units.SI.Temperature | T_start_in | pipeDataULg.T_start_in + 273.15 | Initial temperature at pipe inlet |
| Modelica.Units.SI.Temperature | T_start_out | pipeDataULg.T_start_out + 273.15 | Initial temperature at pipe outlet |
| Modelica.Units.SI.SpecificHeatCapacity | cp_default | Medium.specificHeatCapacityCp(state = sta_default) | Heat capacity of medium |
| Medium.ThermodynamicState | sta_default | Medium.setState_pTX(T = Medium.T_default, p = Medium.p_default, X = Medium.X_default) | Default medium state |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Fluid.Sources.MassFlowSource_T | WaterCityNetwork | Mass flow source | |
| Fluid.HeatExchangers.Heater_T | Boiler | Boiler with adjustable outlet temperature | |
| Fluid.Sources.Boundary_pT | Sewer1 | Mass flow sink | |
| Fluid.Sensors.TemperatureTwoPort | senTem_out | Temperature sensor | |
| Fluid.Sensors.TemperatureTwoPort | senTem_in | Temperature sensor | |
| Modelica.Blocks.Sources.CombiTimeTable | DataReader | Measurement data | |
| Modelica.Blocks.Math.UnitConversions.From_degC | Tout | Ambient temperature in degrees | |
| Buildings.HeatTransfer.Sources.FixedTemperature | TBou | Fixed boundary condition | |
| Modelica.Blocks.Math.UnitConversions.From_degC | Tin | Input temperature into pipe | |
| Data.PipeDataULg151202 | pipeDataULg | ||
| Modelica.Blocks.Math.Gain | gain | Gain to test variations of mass flow rate within measurement uncertainty | |
| PlugFlowPipe | pipe | Pipe | |
| Fluid.Sensors.EnthalpyFlowRate | senEntOut | Outlet enthalpy sensor | |
| Modelica.Blocks.Math.Add | heatLossSim | Difference between inflowing and outflowing enthalpy streams | |
| Modelica.Blocks.Continuous.Integrator | eneLosInt | Integrate model error | |
| Fluid.Sensors.EnthalpyFlowRate | senEntIn | Inlet enthalpy sensor | |
| Modelica.Blocks.Math.Add | delT | Temperature difference between in- and outlet | |
| Modelica.Blocks.Math.Product | heaLosMea | Heat loss from measurement (mflow*cp*DeltaT) | |
| Modelica.Blocks.Math.Gain | gain3 | Specific heat of water | |
| Modelica.Blocks.Math.Feedback | heaLosDiff | Difference between simulated and measurement enthalpy flow difference | |
| Modelica.Blocks.Sources.Constant | Tamb | Ambient temperature in Kelvin |
Contents
| Name | Description |
|---|---|
 Medium |
Revisions
-
April 29, 2026, by Michael Wetter:
Changed configuration of table to cause the parameters to be evaluated, as this leads to more efficient code.
This is for IBPSA, #2111. -
March 7, 2020, by Michael Wetter:
Replaced measured data from specification in Modelica file to external table, as this reduces the computing time.
This is for #1289. -
November 24, 2016 by Bram van der Heijde:
Add pipe thickness for wall capacity calculation and expand documentation section. - April 2, 2016 by Bram van der Heijde:
Change thermal conductivity and put boundary condition in K. - Januar 26, 2016 by Carles Ribas:
First implementation.