modelPipeGroundCoupling
Information
This model considers the conduction heat transfer between the buried pipe wall and the undisturbed ground temperature by adding a dynamic ground layer. The dynamic ground layer is modeled using the radial heat conduction model through a hollow cylinder Buildings.HeatTransfer.Conduction.SingleLayerCylinder. The undisturbed ground temperature is calculated by the model Buildings.BoundaryConditions.GroundTemperature.UndisturbedSoilTemperature. This model can consider an axial discretization of the pipe. A figure highlighting the main variables and parameters is shown below:
References
Ettore Zanetti, David Blum, Michael Wetter (2023) Control development and sizing analysis for a 5th generation district heating and cooling network using Modelica, In Proceedings of the 15th International Modelica Conference. Aachen, Germany, Oct 9-11, 2023.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.Height | lPip | 100 | Pipe length |
| Modelica.Units.SI.Radius | rPip | 0.5 | Pipe external radius |
| Modelica.Units.SI.Radius | thiGroLay | 1.0 | Dynamic ground layer thickness |
| Modelica.Units.SI.Radius | rGroLay | rPip + thiGroLay | Pipe radius plus dynamic ground layer |
| Integer | nSeg | 10 | Number of pipe discretization segments axial direction |
| Integer | nSta | 1 | Number of state variables for dynamic ground layer |
| Modelica.Units.SI.Length | dep | 10 | Depth of buried pipe to calculate ground temperature |
| Buildings.DHC.Examples.Combined.BaseClasses.Zurich | cliCon | Surface temperature climatic conditions | |
| Buildings.HeatTransfer.Data.Soil.Generic | soiDat | Soil thermal properties | |
| Initialization | |||
| Modelica.Units.SI.Temperature | TpipSta | 280.15 | Initial temperature for the pipe, used if steadyStateInitial = false |
| Modelica.Units.SI.Temperature | TGrouBouSta | 283.15 | Initial temperature at ground final layer, used if steadyStateInitial = false |
| Boolean | steadyStateInitial | false | true initializes dT(0)/dt=0, false initializes T(0) at fixed temperature using TpipSta and TGrouBouSta |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.HeatPorts_a[nSeg] | heatPorts | Multiple heat ports that connect to outside of pipe wall |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.HeatTransfer.Conduction.SingleLayerCylinder[nSeg] | groActLay | ||
| BoundaryConditions.GroundTemperature.UndisturbedSoilTemperature | soiTem | ||
| Modelica.Blocks.Sources.RealExpression | soiTemExp | Soil undisturbed temperature | |
| Modelica.Thermal.HeatTransfer.Sources.PrescribedTemperature[nSeg] | groTem | Prescribed ground temperature | |
| Modelica.Blocks.Routing.Replicator | groTemDup | Ground temperature replicator |
Revisions
-
April 10, 2023, by Ettore Zanetti:
First implementation.