modelPartialLoadValveControl
Partial model of a load on hydronic circuit with flow rate modulation by control valve
Extends from Buildings.Fluid.Interfaces.PartialTwoPortInterface (Partial model with two ports and declaration of quantities that are used by many models).
Information
This is a partial model of a thermal load on a hydronic circuit that is composed of Buildings.Fluid.HydronicConfigurations.ActiveNetworks.Examples.BaseClasses.Load and a replaceable configuration component derived from Buildings.Fluid.HydronicConfigurations.Interfaces.PartialHydronicConfiguration that is used to modulate the flow rate through the load component.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Fluid.HydronicConfigurations.Types.Control | typ | Load type | |
| Modelica.Units.SI.MassFlowRate | mLiq_flow_nominal | 1 | Liquid mass flow rate at design conditions |
| Modelica.Units.SI.PressureDifference | dpTer_nominal | 3E4 | Liquid pressure drop across terminal unit at design conditions |
| Modelica.Units.SI.MassFlowRate | mAir_flow_nominal | abs(Q_flow_nominal)/10/1015 | Air mass flow rate at design conditions |
| Modelica.Units.SI.Temperature | TAirEnt_nominal | if typ == Buildings.Fluid.HydronicConfigurations.Types.Control.Heating then 20 + 273.15 else 26 + 273.15 | Air entering temperature at design conditions |
| Modelica.Units.SI.Temperature | TAirEntChg_nominal | 20 + 273.15 | Air entering temperature in change-over mode |
| Modelica.Units.SI.MassFraction | phiAirEnt_nominal | 0.5 | Air entering relative humidity at design conditions |
| Modelica.Units.SI.Temperature | TLiqEnt_nominal | if typ == Buildings.Fluid.HydronicConfigurations.Types.Control.Heating then 60 + 273.15 else 7 + 273.15 | Liquid entering temperature at design conditions |
| Modelica.Units.SI.Temperature | TLiqLvg_nominal | TLiqEnt_nominal + (if typ == Buildings.Fluid.HydronicConfigurations.Types.Control.Heating then -10 else +5) | Liquid leaving temperature at design conditions |
| Modelica.Units.SI.Temperature | TLiqEntChg_nominal | 60 + 273.15 | Liquid entering temperature in change-over mode |
| Modelica.Units.SI.HeatFlowRate | Q_flow_nominal | (MediumLiq.specificEnthalpy_pTX(MediumLiq.p_default, TLiqEnt_nominal, X = MediumLiq.X_default) - MediumLiq.specificEnthalpy_pTX(MediumLiq.p_default, TLiqLvg_nominal, X = MediumLiq.X_default))*mLiq_flow_nominal | Transmitted heat flow rate at design conditions |
| Buildings.Controls.OBC.CDL.Types.SimpleController | controllerType | Buildings.Controls.OBC.CDL.Types.SimpleController.PI | Type of controller |
| 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 | |
| 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 |
| Control valve | |||
| Modelica.Units.SI.PressureDifference | dpValve_nominal | dpTer_nominal | Control valve pressure drop at design conditions |
| Balancing valves | |||
| Modelica.Units.SI.PressureDifference | dpBal1_nominal | 0 | Balancing valve pressure drop at design conditions |
| Control gains | |||
| Real | k | 0.1 | Gain of controller |
| Real | Ti | 60 | Time constant of integrator block |
| Dynamics › Conservation equations | |||
| Modelica.Fluid.Types.Dynamics | energyDynamics | Modelica.Fluid.Types.Dynamics.SteadyState | Type of energy balance: dynamic (3 initialization options) or steady state |
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 | u | Load modulating signal | |
| Buildings.Controls.OBC.CDL.Interfaces.IntegerInput | mode | Operating mode | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | yLoa_actual | Actual load fraction met | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | Q_flow | Total heat flow rate transferred to the load | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | yVal_actual | Valve position feedback |
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.HydronicConfigurations.ActiveNetworks.Examples.BaseClasses.Load | loa | Load | |
| HydronicConfigurations.Interfaces.PartialHydronicConfiguration | con |
Contents
| Name | Description |
|---|---|
 MediumAir | Medium model for air |
 MediumLiq | Medium model for liquid (CHW or HHW) |
Revisions
-
June 30, 2022, by Antoine Gautier:
First implementation.