modelPartialBorefield
Borefield model using single U-tube borehole heat exchanger configuration.Calculates the average fluid temperature T_fts of the borefield for a given (time dependent) load Q_flow
Extends from Buildings.Fluid.Interfaces.PartialTwoPortInterface (Partial model with two ports and declaration of quantities that are used by many models), Buildings.Fluid.Interfaces.TwoPortFlowResistanceParameters (Parameters for flow resistance for models with two ports).
Information
This model simulates a borefield containing one or multiple boreholes
using the parameters in the borFieDat record.
Heat transfer to the soil is modeled using only one borehole heat exchanger (To be added in an extended model). The fluid mass flow rate into the borehole is divided to reflect the per-borehole fluid mass flow rate. The borehole model calculates the dynamics within the borehole itself using an axial discretization and a resistance-capacitance network for the internal thermal resistances between the individual pipes and between each pipe and the borehole wall.
The thermal interaction between the borehole wall and the surrounding soil is modeled using Buildings.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse, which uses a cell-shifting load aggregation technique to calculate the borehole wall temperature after calculating and/or read (from a previous calculation) the borefield's thermal response factor.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | mSenFac | 1 | Factor for scaling the sensible thermal mass of the volume |
| Modelica.Units.SI.Time | tLoaAgg | 300 | Time resolution of load aggregation |
| Integer | nCel | 5 | Number of cells per aggregation level |
| Integer | nSeg | 10 | Number of segments to use in vertical discretization of the boreholes |
| Buildings.Fluid.Geothermal.Borefields.Data.Borefield.Template | borFieDat | Borefield data | |
| Assumptions | |||
| Boolean | allowFlowReversal (from PartialTwoPort) | true | = false to simplify equations, assuming, but not enforcing, no flow reversal |
| Nominal condition | |||
| Modelica.Units.SI.MassFlowRate | m_flow_nominal (from PartialTwoPortInterface) | Nominal mass flow rate | |
| Modelica.Units.SI.PressureDifference | dp_nominal (from TwoPortFlowResistanceParameters) | Pressure difference | |
| Advanced | |||
| Modelica.Units.SI.MassFlowRate | m_flow_small (from PartialTwoPortInterface) | 1E-4*abs(m_flow_nominal) | Small mass flow rate for regularization of zero flow |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialTwoPortInterface) | 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 | Modelica.Fluid.Types.Dynamics.DynamicFreeInitial | Type of energy balance: dynamic (3 initialization options) or steady state |
| Initialization | |||
| Medium.AbsolutePressure | p_start | Medium.p_default | Start value of pressure |
| Modelica.Units.SI.Temperature[nSeg] | TFlu_start | TGro_start | Start value of fluid temperature |
| Advanced › g-function | |||
| Boolean | forceGFunCalc | false | Set to true to force the thermal response to be calculated at the start instead of checking whether this has been pre-computed |
| Integer | nSegGFun | 12 | Number of segments to use in the calculation of the g-function |
| Integer | nClu | 5 | Number of borehole clusters to use in the calculation of the g-function |
| Initialization › Soil | |||
| Modelica.Units.SI.Temperature | TExt0_start | 283.15 | Initial far field temperature |
| Modelica.Units.SI.Temperature[nSeg] | TExt_start | {if z[i] >= z0 then TExt0_start + (z[i] - z0)*dT_dz else TExt0_start for i in 1:nSeg} | Temperature of the undisturbed ground |
| Initialization › Filling material | |||
| Modelica.Units.SI.Temperature[nSeg] | TGro_start | TExt_start | Start value of grout temperature |
| Initialization › Temperature profile | |||
| Modelica.Units.SI.Height | z0 | 10 | Depth below which the temperature gradient starts |
| Real | dT_dz | 0.01 | Vertical temperature gradient of the undisturbed soil for h below z0 |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Fluid.Interfaces.FluidPort_a | port_a (from PartialTwoPort) | Fluid connector a (positive design flow direction is from port_a to port_b) | |
| Modelica.Fluid.Interfaces.FluidPort_b | port_b (from PartialTwoPort) | Fluid connector b (positive design flow direction is from port_a to port_b) | |
| Modelica.Blocks.Interfaces.RealOutput | TBorAve | Average borehole wall temperature in the borefield |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.MassFlowRate | m_flow (from PartialTwoPortInterface) | port_a.m_flow | Mass flow rate from port_a to port_b (m_flow > 0 is design flow direction) |
| Modelica.Units.SI.PressureDifference | dp (from PartialTwoPortInterface) | port_a.p - port_b.p | Pressure difference between port_a and port_b |
| Medium.ThermodynamicState | sta_a (from PartialTwoPortInterface) | if allowFlowReversal then Medium.setState_phX(port_a.p, noEvent(actualStream(port_a.h_outflow)), noEvent(actualStream(port_a.Xi_outflow))) else Medium.setState_phX(port_a.p, noEvent(inStream(port_a.h_outflow)), noEvent(inStream(port_a.Xi_outflow))) | Medium properties in port_a |
| Medium.ThermodynamicState | sta_b (from PartialTwoPortInterface) | if allowFlowReversal then Medium.setState_phX(port_b.p, noEvent(actualStream(port_b.h_outflow)), noEvent(actualStream(port_b.Xi_outflow))) else Medium.setState_phX(port_b.p, noEvent(port_b.h_outflow), noEvent(port_b.Xi_outflow)) | Medium properties in port_b |
| Buildings.Fluid.Geothermal.Borefields.BaseClasses.HeatTransfer.GroundTemperatureResponse | groTemRes | Ground temperature response | |
| Buildings.Fluid.Geothermal.Borefields.BaseClasses.Boreholes.BaseClasses.PartialBorehole | borHol |
Contents
| Name | Description |
|---|---|
 Medium | Medium in the component |
Revisions
-
April 9, 2021, by Michael Wetter:
Corrected placement ofeachkeyword.
See Buildings, PR #2440. -
August 25, 2020, by Filip Jorissen:
Switched port connections formasFloDiv. See #41. -
March 24, 2020, by Damien Picard:
Propagated flowReversal intomasFloDivandmasFloMul. -
June 7, 2019, by Massimo Cimmino:
Converted instances that are not of interest to user to beprotected. -
June 4, 2019, by Massimo Cimmino:
Added an output for the average borehole wall temperature. See #1107. -
April 11, 2019, by Filip Jorissen:
AddedchoicesAllMatchingforborFieDat. See #1117. -
January 18, 2019, by Jianjun Hu:
Limited the media choice to water and glycolWater. See #1050. -
July 2018, by Alex Laferrière:
Changed into a partial model and changed documentation to reflect the new approach used by the borefield models. -
July 2014, by Damien Picard:
First implementation.