modelValvePartial
General control valve model
Extends from ValveBase (General valve model).
Information
It is the base model for control valves, and extends the ValveBase model. It adds the following parameters for configuration:
- parameter Boolean isCompressibleFlow = false. In order to specify the type of flow to consider. If it is made true the flow will be always considered as adiabatic.
- parameter Boolean isLinear = true. To specify the valve characteristics. If made false, the valve will be considered as isopercentual.
- parameter Boolean useFixedAperture = true. If true, the aperture of the valve will be fixed to the value entered manually at the aperture parameter. Otherwise the aperture will be taken from the RealInput connector Opening, making possible the calculation of the aperture outside of the model.
- parameter Real aperture = 1.0. The fraction of aperture of the valve used if useFixedAperture = true.
The following variables are also defined:
- SI.Area KvFlow. The acting Kv of the valve taking into account its aperture, different from the nominal Kv.
- The conditional connector Modelica.Blocks.Interfaces.RealInput Opening, conditioned to useFixedAperture=false. In order to receive the valve aperture by connexion.
- The protected connector Modelica.Blocks.Interfaces.RealInput Aperture.
The implementation of the Aperture connector is done in the standard way: The connectors Opening and Aperture are connected, but if useFixedAperture is made true, the Opening connector disappears, and also the connection. And the equation Aperture=aperture (reading the manual entered value) is activated.
There is also an equation relating the Kv, KvFlow and Aperture, taking into account the selected characteristic of the valve.
And an equation relating flow with KvFlow and differential pressure, if Aperture>0. Otherwise the flow is made equal to 0.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Ports links | |||
| Boolean | useElevDifference (from TwoFluidPorts) | true | introduces, or not, an equation for the ports elevation. Use only in one connector |
| FreeFluids.Types.ElevationOption | elevCalcMethod (from TwoFluidPorts) | FreeFluids.Types.ElevationOption.differential | if useElevDifference==true, selects the equation to use: differential, or absolute for PortB |
| Modelica.Units.SI.Length | elevDifference (from TwoFluidPorts) | 0.0 | used only if previously selected. Positive if PortB higher than PortA |
| Modelica.Units.SI.Length | portBelevation (from TwoFluidPorts) | 0.0 | used only if previously selected. |
| Boolean | calcEnthalpyDifference (from TwoFluidPorts) | true | if true, will calculate the enthalpy difference between ports. Use only in one connector |
| Boolean | passComposition (from TwoFluidPorts) | true | if true, the equation PortA.X=PortB.X will be activated |
| Flow | |||
| FreeFluids.Types.ValveFixOption | fix (from ValveBase) | FreeFluids.Types.ValveFixOption.fixKv | select the value to fix: Kv, pressure drop, or flow |
| Modelica.Units.SI.Area | fixedKv (from ValveBase) | 1.0 | Kv value if it is fixed |
| Modelica.Units.SI.PressureDifference | fixedDP (from ValveBase) | -0.5e5 | negative if PortB.P<PortA.P |
| Modelica.Units.SI.MassFlowRate | fixedFlow (from ValveBase) | 1.0 | fixed mass flow to maintain at Port A. Possitive if flow is in |
| Boolean | isCompressibleFlow | false | if compressible, it will be treated always as adiabatic |
| Boolean | isLinear | true | If true, linear characteristic is applied, otherwise isoporcentual |
| Boolean | useFixedAperture | true | if true the aperture parameter is used. Otherwise aperture is supplied by the connector |
| Real | aperture | 1.0 | maximum just 1 valve should be closed (aperture=0) in a line |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| FreeFluids.Interfaces.FluidPortA | PortA (from TwoFluidPorts) | ||
| FreeFluids.Interfaces.FluidPortB | PortB (from TwoFluidPorts) | ||
| Modelica.Blocks.Interfaces.RealInput | Opening |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Modelica.Units.SI.SpecificEnthalpy | Hdiff (from TwoFluidPorts) | specific enthalpy difference: Port B - Port A | |
| Modelica.Units.SI.PressureDifference | Pdiff (from TwoFluidPorts) | pressure difference: Port B - Port A | |
| Modelica.Units.SI.Area | Kv (from ValveBase) | ||
| Modelica.Units.SI.Area | Cv (from ValveBase) | ||
| Modelica.Units.SI.VolumeFlowRate | Q (from ValveBase) | ||
| Medium.ThermodynamicState | State (from ValveBase) | ||
| Medium.Density | Rho (from ValveBase) | ||
| Medium.Temperature | T (from ValveBase) | Temperature | |
| SI.Area | KvFlow | Kv at actual aperture |