.Annex60.Fluid.HeatExchangers.HeaterCooler_T

Information

Model for an ideal heater or cooler with a prescribed outlet temperature.

This model forces the outlet temperature at port_b to be equal to the temperature of the input signal TSet, subject to optional limits on the heating or cooling capacity Q_flow_max and Q_flow_min. For unlimited capacity, set Q_flow_maxHeat = Modelica.Constant.inf and Q_flow_maxCool=-Modelica.Constant.inf.

The output signal Q_flow is the heat added (for heating) or subtracted (for cooling) to the medium if the flow rate is from port_a to port_b. If the flow is reversed, then Q_flow=0. The outlet temperature at port_a is not affected by this model.

If the parameter energyDynamics is not equal to Modelica.Fluid.Types.Dynamics.SteadyState, the component models the dynamic response using a first order differential equation. The time constant of the component is equal to the parameter tau. This time constant is adjusted based on the mass flow rate using

τ_eff = τ |ṁ| ⁄ ṁ_nom

where τ_eff is the effective time constant for the given mass flow rate ṁ and τ is the time constant at the nominal mass flow rate ṁ_nom. This type of dynamics is equal to the dynamics that a completely mixed control volume would have.

Optionally, this model can have a flow resistance. If no flow resistance is requested, set dp_nominal=0.

For a model that uses a control signal u ∈ [0, 1] and multiplies this with the nominal heating or cooling power, use Annex60.Fluid.HeatExchangers.HeaterCooler_u

Limitations

This model only adds or removes heat for the flow from port_a to port_b. The enthalpy of the reverse flow is not affected by this model.

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 examples Annex60.Fluid.HeatExchangers.Validation.HeaterCooler_T and Annex60.Fluid.HeatExchangers.Validation.HeaterCooler_T_dynamic.

Revisions

• December 1, 2016, by Michael Wetter:
  Updated model as use_dh is no longer a parameter in the pressure drop model.
  This is for #480.
• November 11, 2014, by Michael Wetter:
  Revised implementation.
• March 19, 2014, by Christoph Nytsch-Geusen:
  First implementation.