modelValveVap
Valve for steam flow
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, compressible fluid.
Extends the ValveBase model (see the corresponding documentation for common valve features).
The product Fk*xt is given by the parameter Fxt_full, and is assumed constant by default. The relative change (per unit) of the xt coefficient with the valve opening can be specified by customising the xtfun function.
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 |
| SI.PressureDifference | dpMin (from ValveBase) | 0 | minimum dp to be used for reversal flow calculation |
| Boolean | allowFlowReversal (from ValveBase) | system.allowFlowReversal | = true to allow flow reversal, false restricts to design direction |
| SI.Volume | V (from ValveBase) | 0 | Valve Internal Volume |
| Boolean | useNoEvent (from ValveBase) | false | =true, to avoid events in case of chattering in zero-flow condition |
| Real | Fxt_full | 0.5 | Fk*xt critical ratio at full opening |
| 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 | |||
| Choices.Init.Options | initOpt (from ValveBase) | system.initOpt | Initialisation option |
| Medium.AbsolutePressure | pin_start (from ValveBase) | pnom | Inlet pressure start value |
| Medium.AbsolutePressure | pout_start (from ValveBase) | pnom - dpnom | Inlet pressure start value |
| Medium.SpecificEnthalpy | hstart (from ValveBase) | 1e5 | Specific Enthalpy 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) | ||
| Medium.SpecificEnthalpy | h (from ValveBase) | Fluid specific enthalpy | |
| Medium.SpecificEnthalpy | hin (from ValveBase) | Enthalpy of entering fluid | |
| Medium.SpecificEnthalpy | hout (from ValveBase) | Enthalpy of outgoing fluid | |
| SI.PressureDifference | dp (from ValveBase) | Pressure drop across the valve | |
| SI.PerUnit | theta_act (from ValveBase) | Actual valve opening | |
| Real | x | Pressure drop ratio | |
| Real | xs | Saturated pressure drop ratio | |
| Real | Y | Compressibility factor | |
| Real | Fxt | Fxt coefficient | |
| Medium.AbsolutePressure | p | Inlet pressure |
Contents
| Name | Description |
|---|---|
 xtfun |
Revisions
- 15 Mar 2005
by Francesco Casella:
Rewritten with sqrtReg. - 16 Dec 2004
by Francesco Casella:
Standard medium definition added. - 1 Jul 2004
by Francesco Casella:
Valve model restructured using inheritance.
Adapted to Modelica.Media. - 1 Oct 2003
by Francesco Casella:
First release.