Model for a steam humidifier with a prescribed outlet water vapor mass fraction in kg/kg total air.
This model forces the outlet water mass fraction at port_b to be
no lower than the
input signal X_wSet, subject to optional limits on the
maximum water vapor mass flow rate that is added, as
described by the parameter mWatMax_flow.
By default, the model has unlimited capacity.
The output signal mWat_flow ≥ 0 is the moisture added
to the medium if the flow rate is from port_a to port_b.
If the flow is reversed, then mWat_flow = 0.
The outlet specific enthalpy at port_b is increased by
the enthalpy of steam at 100°C times the mass of steam that was added.
Therefore, the temperature of the leaving fluid is slightly above the inlet temperature.
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
τeff = τ |ṁ| ⁄ ṁnom
where τeff is the effective time constant for the given mass flow rate ṁ and τ is the time constant at the nominal mass flow rate ṁnom. 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 model that uses a control signal u ∈ [0, 1] and multiplies this with the nominal water mass flow rate, use Buildings.Fluid.Humidifiers.Humidifier_u
This model only adds water vapor for the flow from
port_a to port_b.
The water vapor of the reverse flow is not affected by this model.
massDynamics to energyDynamics for consistency with other models.