Moisture Separator (MA)

Removing water vapor and water droplets from the humid air stream.

blockType: AcausalFoundation.MoistAir.Elements.MoistureSeparator

Path in the library:

/Physical Modeling/Fundamental/Moist Air/Elements/Moisture Separator (MA)

Description

Block Moisture Separator (MA) removes a preset proportion of water vapor and water droplets from the flow passing through the unit in the humid air network. It is assumed that the method of moisture removal is mechanical, and the change in flow temperature at the ports is negligible.

If the value is the parameter Nominal density If the pressure drop is greater than zero, then the pressure drop is

where

— mass flow rate on port A;
— parameter value Nominal mass flow rate;
— the proportion of the nominal mass flow rate of the mixture for the transition to laminar flow;
— inlet pressure, or , depending on the flow direction;
— input temperature, or , depending on the flow direction;
— specific gas constant.

Proportionality coefficient equal to

where — parameter value Nominal density, and — parameter value Nominal pressure drop.

If the parameter value is Nominal density If the pressure drop is equal to zero, then the pressure drop is

where is the proportionality coefficient equal to

Since adiabatic flow resistance is assumed in the block, the specific total enthalpy of the mixture is equal to

where

and — specific enthalpies at ports A and B, respectively;
— parameter value Cross-sectional area at ports A and B.

Conservation of mass and energy

The mass conservation equations for moist air, water vapor, impurity gases, and water droplets are as follows:

where

and — mass flow rates of water vapor at ports A and B, respectively;
and — mass consumption of impurity gases at ports A and B, respectively;
and — the mass consumption of water droplets at ports A and B, respectively.

The consumption of the removed water vapor is equal to

where

— parameter value Fraction of water vapor removed;
— mass flow of humid air at port A or B;
— the mass fraction of water vapor at port A or B.

The consumption of the removed water droplets is equal to

where

— parameter value Fraction of water droplets removed;
— the mass ratio of water droplets to moist air at port A or B.

The energy conservation equation:

where and — power consumption through ports A and B, respectively, and — energy consumption from the removed water vapor and water droplets. This term does not represent heat or work and includes only the specific contribution of enthalpy from the removed water vapor and water droplets.:

where and — specific enthalpies of water vapor and water droplets at the inlet port.

Assumptions and limitations

This unit does not simulate any physical or thermodynamic effects associated with the removal of water vapor and water droplets.

Ports

Conserving

# B — input or output port
humid air

Details

The humid air port corresponds to the inlet or outlet of the pipe. This block has no internal orientation.

Program usage name

port_b

# A — input or output port
humid air

Details

The humid air port corresponds to the inlet or outlet of the pipe. This block has no internal orientation.

Program usage name

port_a

Output

# W — consumption of water vapor to be removed, kg/s
scalar

Details

The output port containing the value of the water vapor removal rate in kg/s.

Data types	`Float64`
Complex numbers support	No

# D — consumption of water droplets to be removed, kg/s
scalar

Details

The output port containing the value of the water droplet removal rate in kg/s.

Data types	`Float64`
Complex numbers support	No

Parameters

Main

# Fraction of water droplets removed — proportion of water droplets removed

Details

The proportion of water droplets removed from the humid air flow passing through the unit.

Default value	`0.5`
Program usage name	`removed_droplets_fraction`
Evaluatable	Yes

Details

The mass flow rate of the air mixture through the unit under nominal operating conditions. The unit uses nominal parameters to calculate the proportionality coefficient between pressure drop and mass flow.

Units	`kg/s` \| `kg/hr` \| `kg/min` \| `g/hr` \| `g/min` \| `g/s` \| `t/hr` \| `lbm/hr` \| `lbm/min` \| `lbm/s`
Default value	`0.1 kg/s`
Program usage name	`mdot_nominal`
Evaluatable	Yes

# Cross-sectional area at ports A and B — cross-sectional area of ports A and B
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac

Details

The cross-sectional area of the block ports. The ports are assumed to be of the same size.

Units	`m^2` \| `um^2` \| `mm^2` \| `cm^2` \| `km^2` \| `in^2` \| `ft^2` \| `yd^2` \| `mi^2` \| `ha` \| `ac`
Default value	`0.01 m^2`
Program usage name	`port_area`
Evaluatable	Yes

# Removed water vapor condensed to liquid — remote steam condensation option

Details

The possibility of condensation of the removed water vapor into a liquid. When this option is selected, the unit converts water vapor into liquid before removing it, meaning the latent heat of the water vapor will remain in the stream. In this case, the temperature change throughout the unit may be more significant.

Default value	`false (switched off)`
Program usage name	`vapor_condensed`
Evaluatable	No

# Nominal pressure drop — pressure drop under nominal operating conditions
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg

Details

Pressure drop from inlet to outlet under nominal operating conditions. The unit uses nominal parameters to calculate the proportionality coefficient between pressure drop and mass flow.

Units	`Pa` \| `uPa` \| `hPa` \| `kPa` \| `MPa` \| `GPa` \| `kgf/m^2` \| `kgf/cm^2` \| `kgf/mm^2` \| `mbar` \| `bar` \| `kbar` \| `atm` \| `ksi` \| `psi` \| `mmHg` \| `inHg`
Default value	`0.001 MPa`
Program usage name	`delta_p_nominal`
Evaluatable	Yes

# Fraction of nominal mass flow rate for laminar flow transition — the ratio of the threshold value of the mass flow to the nominal value

Details

The ratio of the threshold mass flow rate to the nominal mass flow rate of the air mixture. The unit uses this parameter to set a threshold value for linearization of the differential pressure.

Default value	`0.001`
Program usage name	`laminar_fraction`
Evaluatable	Yes

# Nominal density — density under nominal operating conditions
kg/m^3 | g/m^3 | g/cm^3 | g/mm^3 | lbm/ft^3 | lbm/gal | lbm/in^3

Details

The mass density of the moist air mixture within the flow resistance under nominal operating conditions. The unit uses nominal parameters to calculate the proportionality coefficient between pressure drop and mass flow. Set this parameter to 0 to ignore the dependence of the pressure drop on the density of the air mixture.

Units	`kg/m^3` \| `g/m^3` \| `g/cm^3` \| `g/mm^3` \| `lbm/ft^3` \| `lbm/gal` \| `lbm/in^3`
Default value	`0 kg/m^3`
Program usage name	`rho_nominal`
Evaluatable	Yes

# Fraction of water vapor removed — fraction of water vapor removed

Details

The proportion of water vapor removed from the humid air flow passing through the unit.

Default value	`0.5`
Program usage name	`removed_vapor_fraction`
Evaluatable	Yes