modelHumidifier_u

Ideal humidifier or dehumidifier with prescribed water mass flow rate addition or subtraction

Extends from Buildings.Fluid.Interfaces.TwoPortHeatMassExchanger.

Information

Model for an air humidifier or dehumidifier.

This model adds (or removes) moisture from the air stream. The amount of exchanged moisture is equal to

ṁwat = u ṁwat,nom,

where u is the control input signal and ṁwat,nom is equal to the parameter mWat_flow_nominal. The parameter mWat_flow_nominal can be positive or negative. If ṁwat is positive, then moisture is added to the air stream, otherwise it is removed.

If the heat port heatPort is unconnected, then the enthalpy of the air that flows through the device remains unchanged, e.g., the humidification is adiabatic. To change the enthalpy of the air, add heat flow to the connector heatPort.

Parameters

TypeNameDefaultDescription
Modelica.Units.SI.MassFlowRatemWat_flow_nominalWater mass flow rate at u=1, positive for humidification

Components

TypeNameDefaultDescription
Modelica.Blocks.Interfaces.RealInputuControl input
Modelica.Blocks.Interfaces.RealOutputmWat_flowWater added to the fluid
Modelica.Thermal.HeatTransfer.Interfaces.HeatPort_aheatPortHeat port for total heat exchange with the control volume

Revisions

  • February 9, 2023, by Michael Wetter:
    Removed access to parameter use_T_in which does not exist in this model.
    This is for #1697.
  • March 7, 2022, by Michael Wetter:
    Removed massDynamics.
    This is for #1542.
  • April 12, 2017, by Michael Wetter:
    Removed parameters use_T_in and T. This removes the optional specification of temperature through the parameter T or the input connector T_in. Exposed the heat port of the control volume to allow adding heat, for example, to use the model as a steam humidifier.
    This is for issue Buildings #704.
  • May 6, 2015, by Michael Wetter:
    Set prescribedHeatFlowRate=true. This is for issue #412.
  • May 29, 2014, by Michael Wetter:
    Removed undesirable annotation Evaluate=true.
  • February 11, 2014 by Michael Wetter:
    Corrected issue #197 which led to twice the amount of latent heat being added to the fluid stream.
  • October 14, 2013 by Michael Wetter:
    Constrained medium to be a subclass of Modelica.Media.Interfaces.PartialCondensingGases, as this base class declares the function enthalpyOfCondensingGas.
  • July 30, 2013 by Michael Wetter:
    Updated model to use new variable mWat_flow in the base class.
  • May 24, 2011, by Michael Wetter:
    Changed base class to allow using the model as a dynamic or a steady-state model.
  • April 14, 2010, by Michael Wetter:
    Converted temperature input to a conditional connector.
  • April 17, 2008, by Michael Wetter:
    First implementation.