modelHeaterCooler_u

Heater or cooler with prescribed heat flow rate

Extends from Buildings.Fluid.Interfaces.TwoPortHeatMassExchanger.

Information

Model for an ideal heater or cooler with prescribed heat flow rate to the medium.

This model adds heat in the amount of Q_flow = u Q_flow_nominal to the medium. The input signal u and the nominal heat flow rate Q_flow_nominal can be positive or negative. A positive value of Q_flow means heating, and negative means cooling.

The outlet conditions at port_a are not affected by this model, other than for a possible pressure difference due to flow friction.

Optionally, this model can have a flow resistance. Set dp_nominal = 0 to disable the flow friction calculation.

For a model that uses as an input the fluid temperature leaving at port_b, use Buildings.Fluid.HeatExchangers.PrescribedOutlet

Limitations

This model does not affect the humidity of the air. Therefore, if used to cool air below the dew point temperature, the water mass fraction will not change.

Validation

The model has been validated against the analytical solution in the example Buildings.Fluid.HeatExchangers.Validation.HeaterCooler_u.

Parameters

TypeNameDefaultDescription
Modelica.Units.SI.HeatFlowRateQ_flow_nominalHeat flow rate at u=1, positive for heating

Components

TypeNameDefaultDescription
Modelica.Blocks.Interfaces.RealInputuControl input
Modelica.Blocks.Interfaces.RealOutputQ_flowHeat added to the fluid

Revisions

  • October 13, 2022, by Fabian Wuellhorst:
    Added unit to instance gai.
    This is for #1642.
  • March 7, 2022, by Michael Wetter:
    Removed massDynamics.
    This is for #1542.
  • November 3, 2016, by Michael Wetter:
    Set preHea(final alpha=0) as this allows to simplify the system of equations.
    This is for #570.
  • November 19, 2015, by Michael Wetter:
    Removed assignment of parameter showDesignFlowDirection in extends statement. This is for #349.
  • May 6, 2015, by Michael Wetter:
    Set prescribedHeatFlowRate=true. This is for issue #412.
  • May 1, 2015, by Marcus Fuchs:
    Corrected typo in documentation.
  • November 12, 2014, by Michael Wetter:
    Added output signal Q_flow so that it has the same output ports as Buildings.Fluid.HeatExchangers.Validation.PrescribedOutlet.
  • September 11, 2014, by Christoph Nytsch-Geusen:
    Renaming class to HeaterCooler_u.
  • October 15, 2013, by Michael Wetter:
    Redeclared the control volume to be final so that it does not show anymore in the parameter window.
  • July 11, 2011, by Michael Wetter:
    Redeclared fluid volume as final. This prevents the fluid volume model to appear in the dialog window.
  • May 24, 2011, by Michael Wetter:
    Changed base class to allow using the model as a dynamic or a steady-state model.
  • April 17, 2008, by Michael Wetter:
    First implementation.