modelTwoWayButterfly

Two way valve with the flow characteristic of a typical butterfly valve

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Extends from Buildings.Fluid.Actuators.Valves.TwoWayPolynomial (Two way valve with polynomial characteristic).

Information

Two way valve with the flow characteristic of a typical butterfly valve as listed below.

Butterfly valve characteristic

Implementation

The model assigns a Kv based on the table at mydatabook.org. The Kv values listed in the parameter Kvs are reasonable assumptions, but the actual value can depend much on the design of the specific valve. Moreover, the Kv values for DN value smaller than DN 150 are a quadratic extrapolation from the value at DN 150.

Parameters

Type	Name	Default	Description
Boolean	homotopyInitialization (from PartialResistance)	true	= true, use homotopy method
Modelica.Units.SI.MassFlowRate	m_flow_turbulent (from PartialResistance)		Turbulent flow if \|m_flow\| >= m_flow_turbulent
Real	l (from PartialTwoWayValve)	0.0001	Valve leakage, l=Kv(y=0)/Kv(y=1)
Real	kFixed (from PartialTwoWayValve)	if dpFixed_nominal > Modelica.Constants.eps then m_flow_nominal/sqrt(dpFixed_nominal) else 0	Flow coefficient of fixed resistance that may be in series with valve, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2).
Real	c (from TwoWayPolynomial)		Polynomial coefficients, starting with fixed offset
Real	Kvs		Kv value at fully open valve
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	dp_nominal (from PartialResistance)		Pressure drop at 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 (from PartialTwoWayValve)	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 (from PartialResistance)	false	= true, use m_flow = f(dp) else dp = f(m_flow)
Real	n (from PartialResistance)	2	Flow exponent, n=1 for laminar, n=2 for turbulent
Boolean	linearized (from PartialResistance)	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
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
Dynamics › Actuator position
Boolean	use_strokeTime (from ActuatorSignal)	true	Set to true to continuously open and close valve using strokeTime
Modelica.Units.SI.Time	strokeTime (from ActuatorSignal)	120	Time needed to fully open or close actuator
Modelica.Blocks.Types.Init	init (from ActuatorSignal)	Modelica.Blocks.Types.Init.InitialOutput	Type of initialization (no init/steady state/initial state/initial output)
Real	y_start (from ActuatorSignal)	1	Initial position of actuator

Connectors

Type	Name	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)
Modelica.Blocks.Interfaces.RealInput	y (from ActuatorSignal)	Actuator position (0: closed, 1: open)
Modelica.Blocks.Interfaces.RealOutput	y_actual (from ActuatorSignal)	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
Real	phi (from PartialTwoWayValve)		Ratio actual to nominal mass flow rate of valve, phi=Kv(y)/Kv(y=1)
Real	kVal (from PartialTwoWayValve)		Flow coefficient of valve, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2).
Real	k (from PartialTwoWayValve)		Flow coefficient of valve and pipe in series, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2).

Revisions

June 10, 2021, by Michael Wetter:
Changed implementation of the filter and changed the parameter order to a constant as most users need not change this value.
This is for #1498.
December 22, 2020 by Michael Wetter:
Add parameter Kvs.
December 20, 2020 by Filip Jorissen:
Revised implementation with default Kv computation.
July 8, 2018 by Filip Jorissen:
First implementation.