modelBorefield
Extends from Buildings.Obsolete.BaseClasses.ObsoleteModel (Icon for classes that are obsolete and will be removed in later versions), Buildings.Fluid.Interfaces.PartialTwoPortInterface (Partial model with two ports and declaration of quantities that are used by many models).
Information
This is a model for a borefield system with a variable speed pump and a mixing valve modulated to maintain a maximum inlet temperature.
The system is controlled based on the logic described in Buildings.Obsolete.DHC.ETS.Combined.Controls.Borefield. The pump flow rate is considered proportional to the pump speed under the assumption of a constant flow resistance in the borefield loop. This assumption is justified by the connection of the loop to the buffer tanks, and by the additional assumption that the bypass branch of the mixing valve is balanced with the direct branch.
(The parameter from_dp of the valve model is set to false to
simplify the system of algebraic equations, which, in this specific case,
alleviates non-convergence issues.)
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.Geothermal.Borefields.Data.Borefield.Example | datBorFie | ||
| Modelica.Units.SI.Pressure | dpValBorFie_nominal | dp_nominal/2 | Nominal pressure drop of control valve |
| Modelica.Units.SI.Temperature | TBorWatEntMax | Maximum value of borefield water entering temperature | |
| Real | spePumBorMin | 0.1 | Borefield pump minimum speed |
| 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.Pressure | dp_nominal | Pressure losses for the entire borefield (control valve excluded) | |
| 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 |
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) | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput[2] | yValIso_actual | Isolation valves return position (fractional) | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | u | Control signal from supervisory | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | PPum | Pump power |
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.Actuators.Valves.ThreeWayEqualPercentageLinear | val | Mixing valve controlling entering temperature | |
| Buildings.DHC.ETS.BaseClasses.Pump_m_flow | pum | Pump with prescribed mass flow rate | |
| Buildings.Fluid.Sensors.TemperatureTwoPort | senTEnt | Entering temperature | |
| BorefieldType | borFie | Geothermal borefield | |
| Buildings.DHC.ETS.BaseClasses.Junction | spl | Flow splitter | |
| Buildings.Fluid.Sensors.TemperatureTwoPort | senTLvg | Leaving temperature | |
| Buildings.Obsolete.DHC.ETS.Combined.Controls.Borefield | con | Controller | |
| Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter | gai1 | Scale to nominal mass flow rate |
Contents
| Name | Description |
|---|---|
 BorefieldType |