modelPartialThreeWayValve

Partial three way valve

Extends from AixLib.Fluid.BaseClasses.PartialThreeWayResistance, AixLib.Fluid.Actuators.BaseClasses.ActuatorSignal, AixLib.Fluid.Actuators.BaseClasses.ValveParameters.

Information

Partial model of a three way valve. This is the base model for valves with different opening characteristics, such as linear, equal percentage or quick opening. The three way valve model consists of a mixer where valves are placed in two of the flow legs. The third flow leg has no friction. The flow coefficient Kv for flow from port_1 → port_2 is a parameter. The flow coefficient for the bypass flow from port_3 → port_2 is computed as 

         Kv(port_3 → port_2)
  fraK = ----------------------
         Kv(port_1 → port_2)

where 0 < fraK ≤ 1 is a parameter with a default value of fraK=0.7.

Since this model uses two way valves to construct a three way valve, see AixLib.Fluid.Actuators.BaseClasses.PartialTwoWayValve for details regarding the valve implementation.

Parameters

TypeNameDefaultDescription
BooleanhomotopyInitializationtrue= true, use homotopy method
RealfraK0.7Fraction Kv(port_3&rarr;port_2)/Kv(port_1&rarr;port_2)
Reall{0.0001, 0.0001}Valve leakage, l=Kv(y=0)/Kv(y=1)
Nominal condition
Modelica.Units.SI.PressureDifference[2]dpFixed_nominal{0, 0}Nominal pressure drop of pipes and other equipment in flow legs at port_1 and port_3
Pressure-flow linearization
RealdeltaM0.02Fraction of nominal flow rate where linearization starts, if y=1
Advanced
Booleanlinearized{false, false}= true, use linear relation between m_flow and dp for any flow rate

Revisions

  • February 3, 2023, by Michael Wetter:
    Removed start value for dp.
    This is for Buildings, #3231.
  • November 16, 2022, by Michael Wetter:
    Propagated parameter riseTime to valves. The value is not used as the filter is disabled, but it will show in the result file. Having a consistent value for all these parameters in the result filter helps during debugging.
  • April 14, 2020, by Michael Wetter:
    Changed homotopyInitialization to a constant.
    This is for IBPSA, #1341.
  • November 5, 2019, by Michael Wetter:
    Moved assignment of leakage from AixLib.Fluid.Actuators.BaseClasses.PartialThreeWayValve to the parent classes.
    This is for #1227.
  • October 25, 2019, by Jianjun Hu:
    Improved icon graphics annotation. This is for #1225.
  • March 24, 2017, by Michael Wetter:
    Renamed filteredInput to use_inputFilter.
    This is for #665.
  • January 22, 2016, by Michael Wetter:
    Corrected type declaration of pressure difference. This is for #404.
  • December 17, 2015, by Michael Wetter:
    Removed assignment redeclare final package Medium=Medium as this is now done in the base class. This is for https://github.com/lbl-srg/modelica-buildings/issues/475.
  • November 23, 2015 by Filip Jorissen:
    Corrected valve leakage value to avoid warnings.
  • February 28, 2013, by Michael Wetter:
    Reformulated assignment of parameters. Removed default value for dpValve_nominal, as this parameter has the attribute fixed=false for some values of CvData. In this case, assigning a value is not allowed. Corrected wrong documentation of parameter fraK(min=0, max=1) = 0.7. The documenation was Fraction Kv(port_1→port_2)/Kv(port_3→port_2) instead of Fraction Kv(port_3→port_2)/Kv(port_1→port_2). Because the parameter set correctly its attributes min=0 and max=1, instances of this model used the correct value.
  • April 12, 2012 by Michael Wetter:
    Removed duplicate declaration of m_flow_nominal.
  • February 20, 2012 by Michael Wetter:
    Renamed parameter dp_nominal to dpValve_nominal, and added new parameter dpFixed_nominal=0. See AixLib.Fluid.Actuators.UsersGuide.
  • March 25, 2011, by Michael Wetter:
    Added homotopy method.
  • June 3, 2008 by Michael Wetter:
    First implementation.