modelValveLiqChoked
Extends from BaseClasses.ValveBase (Base model for valves).
Information
Liquid water valve model according to the IEC 534/ISA S.75 standards for valve sizing, incompressible fluid, with possible choked flow conditions.
Extends the ValveBase model (see the corresponding documentation for common valve features).
The model operating range includes choked flow operation, which takes place for low outlet pressures due to flashing in the vena contracta; otherwise, non-choking conditions are assumed.
The default liquid pressure recovery coefficient Fl is constant and given by the parameter Flnom. The relative change (per unit) of the recovery coefficient can be specified as a given function of the valve opening by customising the Flfun function.
If the flow coefficient is specified in terms of a nominal operating point, this should be in non-chocked conditions.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | fixedAv (from ValveBase) | (if CvData == ThermoPower.Choices.Valve.CvTypes.Av then true else false) | |
| Boolean | CheckValve (from ValveBase) | false | Reverse flow stopped |
| Real | b (from ValveBase) | 0.01 | Regularisation factor |
| Boolean | allowFlowReversal (from ValveBase) | system.allowFlowReversal | = true to allow flow reversal, false restricts to design direction |
| Real | Flnom | 0.9 | Liquid pressure recovery factor |
| Flow Coefficient | |||
| ThermoPower.Choices.Valve.CvTypes | CvData (from ValveBase) | ThermoPower.Choices.Valve.CvTypes.Av | Selection of flow coefficient |
| SI.Area | Av (from ValveBase) | Av (metric) flow coefficient | |
| Real | Kv (from ValveBase) | 0 | Kv (metric) flow coefficient |
| Real | Cv (from ValveBase) | 0 | Cv (US) flow coefficient [USG/min] |
| Valve Opening | |||
| Boolean | useThetaInput (from ValveBase) | true | Use the input connector for the valve opening |
| SI.PerUnit | theta_fix (from ValveBase) | 1 | Fixed opening value when the input connector not used |
| Nominal operating point | |||
| Medium.AbsolutePressure | pnom (from ValveBase) | Nominal inlet pressure | |
| SI.PressureDifference | dpnom (from ValveBase) | Nominal pressure drop | |
| Medium.MassFlowRate | wnom (from ValveBase) | Nominal mass flowrate | |
| Medium.Density | rhonom (from ValveBase) | 1000 | Nominal density |
| SI.PerUnit | thetanom (from ValveBase) | 1 | Nominal valve opening |
| SI.Power | Qnom (from ValveBase) | 0 | Nominal heat loss to ambient |
| Initialisation | |||
| Medium.AbsolutePressure | pin_start (from ValveBase) | pnom | Inlet pressure start value |
| Medium.AbsolutePressure | pout_start (from ValveBase) | pnom - dpnom | Inlet pressure start value |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| FlangeA | inlet (from ValveBase) | ||
| FlangeB | outlet (from ValveBase) | ||
| Modelica.Blocks.Interfaces.RealInput | theta (from ValveBase) | Valve opening in per unit |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Medium.ThermodynamicState | fluidState (from ValveBase) | ||
| ThermoPower.System | system (from ValveBase) | System wide properties | |
| Medium.MassFlowRate | w (from ValveBase) | Mass flow rate | |
| Units.LiquidDensity | rho (from ValveBase) | Inlet density | |
| Medium.Temperature | Tin (from ValveBase) | ||
| SI.PressureDifference | dp (from ValveBase) | Pressure drop across the valve | |
| SI.PerUnit | theta_act (from ValveBase) | Actual valve opening | |
| SI.PerUnit | Ff | Ff coefficient (see IEC/ISA standard) | |
| SI.PerUnit | Fl | Pressure recovery coefficient Fl (see IEC/ISA standard) | |
| Medium.AbsolutePressure | pv | Saturation pressure | |
| SI.Pressure | dpEff | Effective pressure drop |
Contents
| Name | Description |
|---|---|
 Flfun |
Revisions
- 15 Mar 2005
by Francesco Casella:
Rewritten with sqrtReg.
< - 16 Dec 2004
by Francesco Casella:
Standard medium definition added.
li>1 Jul 2004
by Francesco Casella: - 1 Oct 2003
by Francesco Casella:
First release.
Valve model restructured using inheritance.
Adapted to Modelica.Media.