Package Modelica.​Fluid.​Valves
Components for the regulation and control of fluid flow

Information

Extends from Modelica.​Icons.​VariantsPackage (Icon for package containing variants).

Package Contents

NameDescription
BaseClassesBase classes used in the Valves package (only of interest to build new component models)
ValveCompressibleValve for compressible fluids, accounts for choked flow conditions
ValveDiscreteValve for water/steam flows with linear pressure drop
ValveIncompressibleValve for (almost) incompressible fluids
ValveLinearValve for water/steam flows with linear pressure drop
ValveVaporizingValve for possibly vaporizing (almost) incompressible fluids, accounts for choked flow conditions

Model Modelica.​Fluid.​Valves.​ValveIncompressible
Valve for (almost) incompressible fluids

Information

Valve model according to the IEC 534/ISA S.75 standards for valve sizing, incompressible fluids.

The parameters of this model are explained in detail in PartialValve (the base model for valves).

This model assumes that the fluid has a low compressibility, which is always the case for liquids. It can also be used with gases, provided that the pressure drop is lower than 0.2 times the absolute pressure at the inlet, so that the fluid density does not change much inside the valve.

If checkValve is false, the valve supports reverse flow, with a symmetric flow characteristic curve. Otherwise, reverse flow is stopped (check valve behaviour).

The treatment of parameters Kv and Cv is explained in detail in the User's Guide.

Extends from Modelica.​Fluid.​Valves.​BaseClasses.​PartialValve (Base model for valves).

Parameters

TypeNameDefaultDescription
BooleanallowFlowReversalsystem.​allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
AbsolutePressuredp_startdp_nominalGuess value of dp = port_a.p - port_b.p
MassFlowRatem_flow_startm_flow_nominalGuess value of m_flow = port_a.m_flow
MassFlowRatem_flow_smallif system.use_eps_Re then system.eps_m_flow * m_flow_nominal else system.m_flow_smallSmall mass flow rate for regularization of zero flow
Booleanshow_Ttrue= true, if temperatures at port_a and port_b are computed
Booleanshow_V_flowtrue= true, if volume flow rate at inflowing port is computed
CvTypesCvDataModelica.​Fluid.​Types.​CvTypes.​OpPointSelection of flow coefficient
AreaAv Av (metric) flow coefficient
RealKv0Kv (metric) flow coefficient [m3/h]
RealCv0Cv (US) flow coefficient [USG/min]
Pressuredp_nominal Nominal pressure drop
MassFlowRatem_flow_nominal Nominal mass flowrate
Densityrho_nominalMedium.density_pTX(Medium.p_default, Medium.T_default, Medium.X_default)Nominal inlet density
Realopening_nominal1Nominal opening
BooleanfilteredOpeningfalse= true, if opening is filtered with a 2nd order CriticalDamping filter
TimeriseTime1Rise time of the filter (time to reach 99.6 % of an opening step)
RealleakageOpening0.001The opening signal is limited by leakageOpening (to improve the numerics)
BooleancheckValvefalseReverse flow stopped
Booleanuse_Resystem.​use_eps_Re= true, if turbulent region is defined by Re, otherwise by m_flow_small

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
input RealInputopeningValve position in the range 0..1
output RealOutputopening_filteredFiltered valve position in the range 0..1

Model Modelica.​Fluid.​Valves.​ValveVaporizing
Valve for possibly vaporizing (almost) incompressible fluids, accounts for choked flow conditions

Information

Valve model according to the IEC 534/ISA S.75 standards for valve sizing, incompressible fluid at the inlet, and possibly two-phase fluid at the outlet, including choked flow conditions.

The parameters of this model are explained in detail in PartialValve (the base model for valves).

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.

This model requires a two-phase medium model, to describe the liquid and (possible) two-phase conditions.

The default liquid pressure recovery coefficient Fl is constant and given by the parameter Fl_nominal. The relative change (per unit) of the recovery coefficient can be specified as a given function of the valve opening by replacing the FlCharacteristic function.

If checkValve is false, the valve supports reverse flow, with a symmetric flow characteristic curve. Otherwise, reverse flow is stopped (check valve behaviour).

The treatment of parameters Kv and Cv is explained in detail in the User's Guide.

Extends from Modelica.​Fluid.​Valves.​BaseClasses.​PartialValve (Base model for valves).

Parameters

TypeNameDefaultDescription
BooleanallowFlowReversalsystem.​allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
AbsolutePressuredp_startdp_nominalGuess value of dp = port_a.p - port_b.p
MassFlowRatem_flow_startm_flow_nominalGuess value of m_flow = port_a.m_flow
MassFlowRatem_flow_smallif system.use_eps_Re then system.eps_m_flow * m_flow_nominal else system.m_flow_smallSmall mass flow rate for regularization of zero flow
Booleanshow_Ttrue= true, if temperatures at port_a and port_b are computed
Booleanshow_V_flowtrue= true, if volume flow rate at inflowing port is computed
CvTypesCvDataModelica.​Fluid.​Types.​CvTypes.​OpPointSelection of flow coefficient
AreaAv Av (metric) flow coefficient
RealKv0Kv (metric) flow coefficient [m3/h]
RealCv0Cv (US) flow coefficient [USG/min]
Pressuredp_nominal Nominal pressure drop
MassFlowRatem_flow_nominal Nominal mass flowrate
Densityrho_nominalMedium.density_pTX(Medium.p_default, Medium.T_default, Medium.X_default)Nominal inlet density
Realopening_nominal1Nominal opening
BooleanfilteredOpeningfalse= true, if opening is filtered with a 2nd order CriticalDamping filter
TimeriseTime1Rise time of the filter (time to reach 99.6 % of an opening step)
RealleakageOpening0.001The opening signal is limited by leakageOpening (to improve the numerics)
BooleancheckValvefalseReverse flow stopped
RealFl_nominal0.9Liquid pressure recovery factor
Booleanuse_Resystem.​use_eps_Re= true, if turbulent region is defined by Re, otherwise by m_flow_small

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
input RealInputopeningValve position in the range 0..1
output RealOutputopening_filteredFiltered valve position in the range 0..1

Model Modelica.​Fluid.​Valves.​ValveCompressible
Valve for compressible fluids, accounts for choked flow conditions

Information

Valve model according to the IEC 534/ISA S.75 standards for valve sizing, compressible fluid, no phase change, also covering choked-flow conditions.

The parameters of this model are explained in detail in PartialValve (the base model for valves).

This model can be used with gases and vapours, with arbitrary pressure ratio between inlet and outlet.

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 replacing the xtCharacteristic function.

If checkValve is false, the valve supports reverse flow, with a symmetric flow characteristic curve. Otherwise, reverse flow is stopped (check valve behaviour).

The treatment of parameters Kv and Cv is explained in detail in the User's Guide.

Extends from Modelica.​Fluid.​Valves.​BaseClasses.​PartialValve (Base model for valves).

Parameters

TypeNameDefaultDescription
BooleanallowFlowReversalsystem.​allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
AbsolutePressuredp_startdp_nominalGuess value of dp = port_a.p - port_b.p
MassFlowRatem_flow_startm_flow_nominalGuess value of m_flow = port_a.m_flow
MassFlowRatem_flow_smallif system.use_eps_Re then system.eps_m_flow * m_flow_nominal else system.m_flow_smallSmall mass flow rate for regularization of zero flow
Booleanshow_Ttrue= true, if temperatures at port_a and port_b are computed
Booleanshow_V_flowtrue= true, if volume flow rate at inflowing port is computed
CvTypesCvDataModelica.​Fluid.​Types.​CvTypes.​OpPointSelection of flow coefficient
AreaAv Av (metric) flow coefficient
RealKv0Kv (metric) flow coefficient [m3/h]
RealCv0Cv (US) flow coefficient [USG/min]
Pressuredp_nominal Nominal pressure drop
MassFlowRatem_flow_nominal Nominal mass flowrate
Densityrho_nominalMedium.density_pTX(Medium.p_default, Medium.T_default, Medium.X_default)Nominal inlet density
Realopening_nominal1Nominal opening
BooleanfilteredOpeningfalse= true, if opening is filtered with a 2nd order CriticalDamping filter
TimeriseTime1Rise time of the filter (time to reach 99.6 % of an opening step)
RealleakageOpening0.001The opening signal is limited by leakageOpening (to improve the numerics)
BooleancheckValvefalseReverse flow stopped
AbsolutePressurep_nominal Nominal inlet pressure
RealFxt_full0.5Fk*xt critical ratio at full opening
Booleanuse_Resystem.​use_eps_Re= true, if turbulent region is defined by Re, otherwise by m_flow_small

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
input RealInputopeningValve position in the range 0..1
output RealOutputopening_filteredFiltered valve position in the range 0..1

Model Modelica.​Fluid.​Valves.​ValveLinear
Valve for water/steam flows with linear pressure drop

Information

This very simple model provides a pressure drop which is proportional to the flowrate and to the opening input, without computing any fluid property. It can be used for testing purposes, when a simple model of a variable pressure loss is needed.

A medium model must be nevertheless be specified, so that the fluid ports can be connected to other components using the same medium model.

The model is adiabatic (no heat losses to the ambient) and neglects changes in kinetic energy from the inlet to the outlet.

Extends from Modelica.​Fluid.​Interfaces.​PartialTwoPortTransport (Partial element transporting fluid between two ports without storage of mass or energy).

Parameters

TypeNameDefaultDescription
BooleanallowFlowReversalsystem.​allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
AbsolutePressuredp_start0.01 * system.p_startGuess value of dp = port_a.p - port_b.p
MassFlowRatem_flow_startsystem.​m_flow_startGuess value of m_flow = port_a.m_flow
MassFlowRatem_flow_smallif system.use_eps_Re then system.eps_m_flow * system.m_flow_nominal else system.m_flow_smallSmall mass flow rate for regularization of zero flow
Booleanshow_Ttrue= true, if temperatures at port_a and port_b are computed
Booleanshow_V_flowtrue= true, if volume flow rate at inflowing port is computed
AbsolutePressuredp_nominal Nominal pressure drop at full opening
MassFlowRatem_flow_nominal Nominal mass flowrate at full opening
final HydraulicConductancekm_flow_nominal / dp_nominalHydraulic conductance at full opening

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
input RealInputopening=1: completely open, =0: completely closed

Model Modelica.​Fluid.​Valves.​ValveDiscrete
Valve for water/steam flows with linear pressure drop

Information

This very simple model provides a (small) pressure drop which is proportional to the flowrate if the Boolean open signal is true. Otherwise, the mass flow rate is zero. If opening_min > 0, a small leakage mass flow rate occurs when open = false.

This model can be used for simplified modelling of on-off valves, when it is not important to accurately describe the pressure loss when the valve is open. Although the medium model is not used to determine the pressure loss, it must be nevertheless be specified, so that the fluid ports can be connected to other components using the same medium model.

The model is adiabatic (no heat losses to the ambient) and neglects changes in kinetic energy from the inlet to the outlet.

In a diagram animation, the valve is shown in "green", when it is open.

Extends from Modelica.​Fluid.​Interfaces.​PartialTwoPortTransport (Partial element transporting fluid between two ports without storage of mass or energy).

Parameters

TypeNameDefaultDescription
BooleanallowFlowReversalsystem.​allowFlowReversal= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
AbsolutePressuredp_start0.01 * system.p_startGuess value of dp = port_a.p - port_b.p
MassFlowRatem_flow_startsystem.​m_flow_startGuess value of m_flow = port_a.m_flow
MassFlowRatem_flow_smallif system.use_eps_Re then system.eps_m_flow * system.m_flow_nominal else system.m_flow_smallSmall mass flow rate for regularization of zero flow
Booleanshow_Ttrue= true, if temperatures at port_a and port_b are computed
Booleanshow_V_flowtrue= true, if volume flow rate at inflowing port is computed
AbsolutePressuredp_nominal Nominal pressure drop at full opening=1
MassFlowRatem_flow_nominal Nominal mass flowrate at full opening=1
final HydraulicConductancekm_flow_nominal / dp_nominalHydraulic conductance at full opening=1
Realopening_min0Remaining opening if closed, causing small leakage flow

Connectors

TypeNameDescription
FluidPort_aport_aFluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_bport_bFluid connector b (positive design flow direction is from port_a to port_b)
input BooleanInputopen 

Generated 2018-12-12 12:13:25 EST by MapleSim.