modelTwoWayValve
Container class for two-way valves
Extends from Buildings.Fluid.Interfaces.PartialTwoPortInterface (Partial model with two ports and declaration of quantities that are used by many models), Buildings.Fluid.Interfaces.LumpedVolumeDeclarations (Declarations for lumped volumes), Buildings.Fluid.Actuators.BaseClasses.ValveParameters (Model with parameters for valves).
Information
This is a container class for two-way valve models from Buildings.Fluid.Actuators.Valves. Note that the models Buildings.Fluid.Actuators.Valves.TwoWayPolynomial and Buildings.Fluid.Actuators.Valves.TwoWayQuickOpening are not represented.
The parameter typCha allows configuring the model
by selecting the valve characteristic to be used based on the enumeration
Buildings.Fluid.HydronicConfigurations.Types.ValveCharacteristic.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Real | l | 0.0001 | Valve leakage, l=Kv(y=0)/Kv(y=1) |
| Buildings.Fluid.Actuators.Valves.Data.Generic | flowCharacteristics | Table with flow characteristics | |
| Real | R | 50 | Rangeability, R=50...100 typically |
| Real | delta0 | 0.01 | Range of significant deviation from equal percentage law |
| 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 | dpValve_nominal (from ValveParameters) | Nominal pressure drop of fully open valve, used if CvData=Buildings.Fluid.Types.CvTypes.OpPoint | |
| Modelica.Units.SI.PressureDifference | dpFixed_nominal | 0 | Pressure drop of pipe and other resistances that are in series |
| 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 |
| Boolean | from_dp | false | = true, use m_flow = f(dp) else dp = f(m_flow) |
| Boolean | linearized | false | = true, use linear relation between m_flow and dp for any flow rate |
| Advanced › Diagnostics | |||
| Boolean | show_T (from PartialTwoPortInterface) | false | = true, if actual temperature at port is computed |
| 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 |
| Flow Coefficient | |||
| Buildings.Fluid.Types.CvTypes | CvData (from ValveParameters) | Buildings.Fluid.Types.CvTypes.OpPoint | Selection of flow coefficient |
| Real | Kv (from ValveParameters) | Kv (metric) flow coefficient [m3/h/(bar)^(1/2)] | |
| Real | Cv (from ValveParameters) | Cv (US) flow coefficient [USG/min/(psi)^(1/2)] | |
| Modelica.Units.SI.Area | Av (from ValveParameters) | Av (metric) flow coefficient | |
| Pressure-flow linearization | |||
| Real | deltaM (from ValveParameters) | 0.02 | Fraction of nominal flow rate where linearization starts, if y=1 |
| Advanced › Nominal condition | |||
| Modelica.Units.SI.Density | rhoStd (from ValveParameters) | Inlet density for which valve coefficients are defined | |
| Configuration | |||
| Buildings.Fluid.HydronicConfigurations.Types.ValveCharacteristic | typCha | Buildings.Fluid.HydronicConfigurations.Types.ValveCharacteristic.EqualPercentage | Valve characteristic |
| Dynamics › Time needed to open or close valve | |||
| Boolean | use_strokeTime | true | Set to true to continuously open and close valve |
| Modelica.Units.SI.Time | strokeTime | 120 | Time needed to open or close valve |
| Modelica.Blocks.Types.Init | init | Modelica.Blocks.Types.Init.InitialOutput | Type of initialization (no init/steady state/initial state/initial output) |
| Real | y_start | 1 | Initial position of actuator |
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 | y | Input control signal | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | y_actual | Actual actuator position |
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 |
| Actuators.Valves.TwoWayEqualPercentage | valEqu | Two-way valve with equal percentage characteristic | |
| Actuators.Valves.TwoWayLinear | valLin | Two-way valve with linear characteristic | |
| Actuators.Valves.TwoWayTable | valTab | Two-way valve with table-specified characteristic | |
| Actuators.Valves.TwoWayPressureIndependent | valPre | Pressure-independent two-way valve |
Revisions
-
June 30, 2022, by Antoine Gautier:
First implementation.