modelTemperatureWetBulbTwoPort

Ideal wet bulb temperature sensor
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Extends from Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor (Partial component to model sensors that measure flow properties using a dynamic model).

Information

This sensor outputs the wet bulb temperature of the medium in the flow between its fluid ports. The sensor is ideal, i.e., it does not influence the fluid. If the parameter tau is non-zero, then its output is computed using a first order differential equation. Setting tau=0 is not recommend. See Buildings.Fluid.Sensors.UsersGuide for an explanation.

Parameters

TypeNameDefaultDescription
Modelica.Units.SI.Timetau (from PartialDynamicFlowSensor)1Time constant at nominal flow rate (use tau=0 for steady-state sensor, but see user guide for potential problems)
Assumptions
BooleanallowFlowReversal (from PartialTwoPort)true= false to simplify equations, assuming, but not enforcing, no flow reversal
Nominal condition
Modelica.Units.SI.MassFlowRatem_flow_nominal (from PartialFlowSensor)Nominal mass flow rate, used for regularization near zero flow
Advanced
Modelica.Units.SI.MassFlowRatem_flow_small (from PartialFlowSensor)1E-4*m_flow_nominalFor bi-directional flow, temperature is regularized in the region |m_flow| < m_flow_small (m_flow_small > 0 required)
Initialization
Modelica.Blocks.Types.InitinitType (from PartialDynamicFlowSensor)Modelica.Blocks.Types.Init.InitialStateType of initialization (InitialState and InitialOutput are identical)
Modelica.Units.SI.TemperatureTWetBul_startMedium.T_defaultInitial or guess value of wet bulb temperature (used to compute initial output signal))

Connectors

TypeNameDefaultDescription
Modelica.Fluid.Interfaces.FluidPort_aport_a (from PartialTwoPort)Fluid connector a (positive design flow direction is from port_a to port_b)
Modelica.Fluid.Interfaces.FluidPort_bport_b (from PartialTwoPort)Fluid connector b (positive design flow direction is from port_a to port_b)
Modelica.Blocks.Interfaces.RealOutputTWet bulb temperature in port medium

Revisions

  • June 25, 2026, by Michael Wetter:
    Added nominal attribute to state variable.
    This is for IBPSA, #2132.
  • October 24, 2022, by Michael Wetter:
    Improved conversion from Xi to X so that it also works with media that have reducedX=true.
    See #1650.
  • February 21, 2020, by Michael Wetter:
    Changed icon to display its operating state.
    This is for #1294.
  • January 18, 2016 by Filip Jorissen:
    Using parameter tauInv since this now exists in Buildings.Fluid.Sensors.BaseClasses.PartialDynamicFlowSensor. This is for #372.
  • September 10, 2013 by Michael Wetter:
    Set start attribute for wetBulMod to use consistent start values within this model.
  • June 3, 2011 by Michael Wetter:
    Revised implementation to add dynamics in such a way that the time constant increases as the mass flow rate tends to zero. This significantly improves the numerics.
  • February 18, 2010, by Michael Wetter:
    Revised model to use new block for computing the wet bulb temperature.
  • September 10, 2008, by Michael Wetter:
    Renamed output port to have the same interfaces as the dry bulb temperature sensor.
  • May 5, 2008, by Michael Wetter:
    First implementation. Implementation is based on Buildings.Fluid.Sensors.Temperature.