modelBoreholeSegment
Vertical segment of a borehole
Extends from Buildings.Fluid.Interfaces.PartialFourPortInterface (Partial model with four ports and declaration of quantities that are used by many models), Buildings.Fluid.Interfaces.TwoPortFlowResistanceParameters (Parameters for flow resistance for models with two ports), Buildings.Fluid.Interfaces.LumpedVolumeDeclarations (Declarations for lumped volumes).
Information
Horizontal layer that is used to model a U-tube borehole heat exchanger. This model combines three models, each simulating a different aspect of a borehole heat exchanger.
The instance pipFil computes the heat transfer in the pipes and the filling material.
This computation is done using the model
Buildings.Fluid.Geothermal.Boreholes.BaseClasses.HexInternalElement.
The instance soi computes transient and steady state heat transfer in the soil using a vertical cylinder.
The computation is done using the model
Buildings.HeatTransfer.Conduction.SingleLayerCylinder.
The model TBouCon computes the far-field temperature boundary condition,
i.e., the temperature at the outer
surface of the above cylindrical heat transfer computation.
The computation is done using the model
Buildings.Fluid.Geothermal.Boreholes.BaseClasses.SingleUTubeBoundaryCondition.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | homotopyInitialization | true | = true, use homotopy method |
| Modelica.Units.SI.Radius | rBor | 0.1 | Radius of the borehole |
| Modelica.Units.SI.Height | hSeg | Height of the element | |
| Modelica.Units.SI.Length | xC | 0.05 | Shank spacing, defined as the distance between the center of a pipe and the center of the borehole |
| Assumptions | |||
| Boolean | allowFlowReversal1 (from PartialFourPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 1 |
| Boolean | allowFlowReversal2 (from PartialFourPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal for medium 2 |
| Boolean | allowFlowReversal | true | = true to allow flow reversal, false restricts to design direction (port_a -> port_b) |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | m1_flow_nominal (from PartialFourPortInterface) | Nominal mass flow rate | |
| Modelica.Units.SI.MassFlowRate | m2_flow_nominal (from PartialFourPortInterface) | Nominal mass flow rate | |
| Modelica.Units.SI.PressureDifference | dp_nominal (from TwoPortFlowResistanceParameters) | Pressure difference | |
| Modelica.Units.SI.MassFlowRate | m_flow_nominal | Nominal mass flow rate | |
| Advanced | |||
| Medium1.MassFlowRate | m1_flow_small (from PartialFourPortInterface) | 1E-4*abs(m1_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Medium2.MassFlowRate | m2_flow_small (from PartialFourPortInterface) | 1E-4*abs(m2_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Modelica.Units.SI.MassFlowRate | m_flow_small | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialFourPortInterface) | false | = true, if actual temperature at port is computed |
| Flow resistance | |||
| Boolean | computeFlowResistance (from TwoPortFlowResistanceParameters) | true | =true, compute flow resistance. Set to false to assume no friction |
| Boolean | from_dp (from TwoPortFlowResistanceParameters) | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Real | n (from TwoPortFlowResistanceParameters) | 2 | Flow exponent, n=1 for laminar, n=2 for turbulent |
| Boolean | linearizeFlowResistance (from TwoPortFlowResistanceParameters) | false | = true, use linear relation between m_flow and dp for any flow rate |
| Real | deltaM (from TwoPortFlowResistanceParameters) | 0.1 | Fraction of nominal flow rate where flow transitions to laminar |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics (from LumpedVolumeDeclarations) | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Modelica.Fluid.Types.Dynamics | substanceDynamics (from LumpedVolumeDeclarations) | energyDynamics | Type of independent mass fraction balance: dynamic (3 initialization options) or steady state |
| Modelica.Fluid.Types.Dynamics | traceDynamics (from LumpedVolumeDeclarations) | energyDynamics | Type of trace substance balance: dynamic (3 initialization options) or steady state |
| Advanced › Dynamics | |||
| Modelica.Fluid.Types.Dynamics | massDynamics (from LumpedVolumeDeclarations) | energyDynamics | Type of mass balance: dynamic (3 initialization options) or steady state, must be steady state if energyDynamics is steady state |
| Initialization | |||
| Medium.AbsolutePressure | p_start (from LumpedVolumeDeclarations) | Medium.p_default | Start value of pressure |
| Medium.Temperature | T_start (from LumpedVolumeDeclarations) | Medium.T_default | Start value of temperature |
| Medium.MassFraction[Medium.nX] | X_start (from LumpedVolumeDeclarations) | Medium.X_default | Start value of mass fractions m_i/m |
| Medium.ExtraProperty[Medium.nC] | C_start (from LumpedVolumeDeclarations) | fill(0, Medium.nC) | Start value of trace substances |
| Medium.ExtraProperty[Medium.nC] | C_nominal (from LumpedVolumeDeclarations) | fill(1E-2, Medium.nC) | Nominal value of trace substances. (Set to typical order of magnitude.) |
| Dynamics | |||
| Real | mSenFac (from LumpedVolumeDeclarations) | 1 | Factor for scaling the sensible thermal mass of the volume |
| Soil | |||
| Buildings.HeatTransfer.Data.Soil.Generic | matSoi | Thermal properties of soil | |
| Modelica.Units.SI.Radius | rExt | 3 | Radius of the soil used for the external boundary condition |
| Modelica.Units.SI.Temperature | TExt_start | 283.15 | Initial far field temperature |
| Integer | nSta | 10 | Number of state variables in the soil |
| Modelica.Units.SI.Time | samplePeriod | 604800 | Sample period for the external boundary condition |
| Filling material | |||
| Buildings.HeatTransfer.Data.BoreholeFillings.Generic | matFil | Thermal properties of the filling material | |
| Modelica.Units.SI.Temperature | TFil_start | 283.15 | Initial temperature of the filling material |
| Tubes | |||
| Modelica.Units.SI.Radius | rTub | 0.02 | Radius of the tubes |
| Modelica.Units.SI.ThermalConductivity | kTub | 0.5 | Thermal conductivity of the tubes |
| Modelica.Units.SI.Length | eTub | 0.002 | Thickness of the tubes |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.FluidPort_a | port_a1 (from PartialFourPort) | Fluid connector a1 (positive design flow direction is from port_a1 to port_b1) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b1 (from PartialFourPort) | Fluid connector b1 (positive design flow direction is from port_a1 to port_b1) | |
| Modelica.Fluid.Interfaces.FluidPort_a | port_a2 (from PartialFourPort) | Fluid connector a2 (positive design flow direction is from port_a2 to port_b2) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b2 (from PartialFourPort) | Fluid connector b2 (positive design flow direction is from port_a2 to port_b2) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium1.MassFlowRate | m1_flow (from PartialFourPortInterface) | port_a1.m_flow | Mass flow rate from port_a1 to port_b1 (m1_flow > 0 is design flow direction) |
| Modelica.Units.SI.PressureDifference | dp1 (from PartialFourPortInterface) | port_a1.p - port_b1.p | Pressure difference between port_a1 and port_b1 |
| Medium2.MassFlowRate | m2_flow (from PartialFourPortInterface) | port_a2.m_flow | Mass flow rate from port_a2 to port_b2 (m2_flow > 0 is design flow direction) |
| Modelica.Units.SI.PressureDifference | dp2 (from PartialFourPortInterface) | port_a2.p - port_b2.p | Pressure difference between port_a2 and port_b2 |
| Medium1.ThermodynamicState | sta_a1 (from PartialFourPortInterface) | if allowFlowReversal1 then Medium1.setState_phX(port_a1.p, noEvent(actualStream(port_a1.h_outflow)), noEvent(actualStream(port_a1.Xi_outflow))) else Medium1.setState_phX(port_a1.p, inStream(port_a1.h_outflow), inStream(port_a1.Xi_outflow)) | Medium properties in port_a1 |
| Medium1.ThermodynamicState | sta_b1 (from PartialFourPortInterface) | if allowFlowReversal1 then Medium1.setState_phX(port_b1.p, noEvent(actualStream(port_b1.h_outflow)), noEvent(actualStream(port_b1.Xi_outflow))) else Medium1.setState_phX(port_b1.p, port_b1.h_outflow, port_b1.Xi_outflow) | Medium properties in port_b1 |
| Medium2.ThermodynamicState | sta_a2 (from PartialFourPortInterface) | if allowFlowReversal2 then Medium2.setState_phX(port_a2.p, noEvent(actualStream(port_a2.h_outflow)), noEvent(actualStream(port_a2.Xi_outflow))) else Medium2.setState_phX(port_a2.p, inStream(port_a2.h_outflow), inStream(port_a2.Xi_outflow)) | Medium properties in port_a2 |
| Medium2.ThermodynamicState | sta_b2 (from PartialFourPortInterface) | if allowFlowReversal2 then Medium2.setState_phX(port_b2.p, noEvent(actualStream(port_b2.h_outflow)), noEvent(actualStream(port_b2.Xi_outflow))) else Medium2.setState_phX(port_b2.p, port_b2.h_outflow, port_b2.Xi_outflow) | Medium properties in port_b2 |
| Buildings.Fluid.Geothermal.Boreholes.BaseClasses.HexInternalElement | pipFil | Internal part of the borehole including the pipes and the filling material | |
| Buildings.HeatTransfer.Conduction.SingleLayerCylinder | soi | Heat conduction in the soil | |
| Buildings.Fluid.Geothermal.Boreholes.BaseClasses.SingleUTubeBoundaryCondition | TBouCon | Thermal boundary condition for the far-field |
Contents
| Name | Description |
|---|---|
 Medium | Medium in the component |
Revisions
-
April 14, 2020, by Michael Wetter:
ChangedhomotopyInitializationto a constant.
This is for IBPSA, #1341. -
February 14, 2014, by Michael Wetter:
Removed unused parametersB0andB1. Updated hyperlinks in the documentation. -
October 8, 2013, by Michael Wetter:
Removed parametershow_V_flow. -
July 28 2011, by Pierre Vigouroux:
First implementation.