BuildSysPro.IBPSA.Fluid.Humidifiers.SprayAirWasher_X

# .BuildSysPro.IBPSA.Fluid.Humidifiers.SprayAirWasher_X

Spray air washer with leaving water mass fraction as input

## Information

Model for a spray air washer 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 liquid water at 10°C times the mass of water that was added. Therefore, the temperature of the leaving fluid is below 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 IBPSA.Fluid.Humidifiers.Humidifier_u

#### Limitations

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.

This model does not affect the enthalpy of the air. Therefore, if water is added, the temperature will decrease, e.g., the humidification is adiabatic.

## Revisions

- March 8, 2022, by Michael Wetter:
  Renamed parameter `massDynamics` to `energyDynamics` for consistency with other models.
- December 14, 2018, by Michael Wetter:
  Restricted base class for medium to one that implements the function `enthalpyOfLiquid`.
  This is for #1057.
- May 3, 2017, by Michael Wetter:
  First implementation.

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