.AixLib.Fluid.HeatExchangers.SensibleCooler_T

Information

Model for an ideal sensible-only cooler that controls its outlet temperature to a prescribed outlet temperature.

This model forces the outlet temperature at port_b to be no higher than the temperature of the input signal TSet, subject to optional limits on the capacity. By default, the model has unlimited cooling capacity.

The output signal Q_flow ≤ 0 is the heat added to the medium if the mass flow rate is from port_a to port_b. If the flow is reversed, then Q_flow=0.

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

If the parameter energyDynamics is different from 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. Set dp_nominal = 0 to disable the flow friction calculation.

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

Limitations

If the flow is from port_b to port_a, then the enthalpy of the medium 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 AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet and AixLib.Fluid.HeatExchangers.Validation.PrescribedOutlet_dynamic.

Revisions

• September 10, 2018, by Michael Wetter:
  Corrected missing propagation of initial conditions.
  This is for AixLib, #1016.
• May 3, 2017, by Michael Wetter:
  First implementation.
  This is for AixLib, #763.