modelMSLAIT

Validation pipe against data from Austrian Institute of Technology with standard library components

Extends from Modelica.Icons.Example.

Information

The example contains experimental data from a real district heating network. This data is used to validate this library's IDEAS.Fluid.FixedResistances.PlugFlowPipe in IDEAS.Fluid.FixedResistances.Validation.PlugFlowPipes.PlugFlowAIT. This model compares its performance with the original Modelica Standard Library pipes, using one discretization element per unit length of pipe. For a coarser discretization, please refer to MSLAIT2Nodes.

Note that these three models are identical, except for the pipe model that is used:

This comparison between different discretization levels and pipe models is made to check the influence of the discretization and pipe model on computation time and simulation accuracy.

The pipes' temperatures are not initialized, thus results of outflow temperature before approximately the first 10000 seconds should not be considered.

Test bench schematic

Schematic of test district heating network

Calibration

To calculate the length specific thermal resistance R of the pipe, the thermal resistance of the surrounding ground is added.

R=1/(0.208)+1/(2   lambda_g   Modelica.Constants.pi)   log(1/0.18)

Where the thermal conductivity of the ground lambda_g = 2.4 W/(m K).

Parameters

TypeNameDefaultDescription
BooleanallowFlowReversalfalse= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Modelica.Units.SI.ThermalResistanceR1/(2*kIns*Modelica.Constants.pi)*log(0.18/0.0899) + 1/(2*2.4*Modelica.Constants.pi)*log(2/0.18)Thermal resistance of main pipes
Modelica.Units.SI.ThermalResistanceR801/(2*0.024*Modelica.Constants.pi)*log(0.07/0.0337) + 1/(2*2.4*Modelica.Constants.pi)*log(2/0.07)Thermal resistance of service pipes
Modelica.Units.SI.ThermalConductivitykIns0.024Heat conductivity of pipe insulation material
Modelica.Units.SI.LengthdIns0.045Thickness of pipe insulation
Modelica.Units.SI.Diameterdiameter0.089Outer diameter of pipe
Modelica.Units.SI.MassFlowRatem_flow_nominal1Nominal mass flow rate, used for regularization near zero flow
Modelica.Units.SI.TimetauHeaTra6500Time constant for heat transfer, default 20 minutes

Components

TypeNameDefaultDescription
Fluid.Sources.MassFlowSource_TPoint1Mass flow source
Fluid.Sources.MassFlowSource_TPoint4Substation 4
Fluid.Sources.MassFlowSource_TPoint3Substation 3
Fluid.Sources.MassFlowSource_TPoint2Substation 2
Modelica.Blocks.Sources.CombiTimeTableDataReaderRead measurement data
Data.PipeDataAIT151218pipeDataAIT151218Record with measurement data
Modelica.Blocks.Sources.RealExpressionm_flow_p3Mass flow rate for substation 3
Modelica.Blocks.Sources.RealExpressionm_flow_p2Mass flow rate for substation 2
Modelica.Blocks.Sources.RealExpressionT_p1Inlet temperature
IDEAS.Fluid.Sources.Boundary_pTExcludedBranchMass flow sink for excluded branch
Modelica.Thermal.HeatTransfer.Sources.PrescribedTemperatureprescribedTemperatureVariable environment temperature
Modelica.Fluid.Pipes.DynamicPipepip0Pipe 0
Modelica.Fluid.Systemsystem
Modelica.Thermal.HeatTransfer.Components.ThermalResistor[pip0.nNodes]res0Thermal resistances for pipe 0
Modelica.Thermal.HeatTransfer.Components.ThermalCollectorcol0Combine heat flows to one
Modelica.Fluid.Pipes.DynamicPipepip1Pipe 1
Modelica.Thermal.HeatTransfer.Components.ThermalCollectorcol1Combine heat flows to one
Modelica.Thermal.HeatTransfer.Components.ThermalResistor[pip1.nNodes]res1Thermal resistances for pipe 1
Modelica.Fluid.Pipes.DynamicPipepip2Pipe 2
Modelica.Thermal.HeatTransfer.Components.ThermalCollectorcol2Combine heat flows to one
Modelica.Thermal.HeatTransfer.Components.ThermalResistor[pip2.nNodes]res2Thermal resistances for pipe 2
Modelica.Fluid.Pipes.DynamicPipepip3Pipe 3
Modelica.Thermal.HeatTransfer.Components.ThermalCollectorcol3Combine heat flows to one
Modelica.Thermal.HeatTransfer.Components.ThermalResistor[pip3.nNodes]res3Thermal resistances for pipe 3
Modelica.Fluid.Pipes.DynamicPipepip4Pipe 4
Modelica.Thermal.HeatTransfer.Components.ThermalCollectorcol4Combine heat flows to one
Modelica.Thermal.HeatTransfer.Components.ThermalResistor[pip4.nNodes]res4Thermal resistances for pipe 4
Modelica.Fluid.Pipes.DynamicPipepip5Pipe 5
Modelica.Thermal.HeatTransfer.Components.ThermalCollectorcol5Combine heat flows to one
Modelica.Thermal.HeatTransfer.Components.ThermalResistor[pip5.nNodes]res5Thermal resistances for pipe 5
Fluid.Sensors.TemperatureTwoPortsenTem_p2Temperature sensor
Fluid.Sensors.TemperatureTwoPortsenTem_p3Temperature sensor
Fluid.Sensors.TemperatureTwoPortsenTemIn_p2Temperature sensor
Fluid.Sensors.TemperatureTwoPortsenTem_p1Temperature sensor
Fluid.Sensors.TemperatureTwoPortsenTem_p4Temperature sensor
Fluid.Sources.MassFlowSource_TPoint5Mass flow sink for substation 4 in case of low flow rates
Modelica.Blocks.Sources.RealExpressionm_flow_p4Measured mass flow rate for substation 4
Modelica.Blocks.Logical.SwitchswitchSwitch to avoid mass flow rate measurement noise on substation with flow standstill.
Modelica.Blocks.Sources.RealExpressionm_flow_zeroDefault value when mass flow rate is below noise threshold
Modelica.Blocks.Logical.LessThresholdlessThresholdCheck if mass flow rate is lower than 0.001
Modelica.Blocks.Logical.Switchswitch1If flow is lower than measurement noise threshold, bypass temperature sensor

Contents

NameDescription
Medium

Revisions

  • 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.
  • May 15, 2019, by Jianjun Hu:
    Replaced fluid source. This is for #1072.
  • November 28, 2016 by Bram van der Heijde:
    Remove pipVol.
  • August 24, 2016 by Bram van der Heijde:
    Implement validation with MSL pipes for comparison, based on AIT validation.
  • July 4, 2016 by Bram van der Heijde:
    Added parameters to test the influence of allowFlowReversal and the presence of explicit volumes in the pipe.
  • January 26, 2016 by Carles Ribas:
    First implementation.