Interface (G-MA)

The boundary between the gas and humid air networks.

blockType: EngeeFluids.Interfaces.GasMoistAir

Path in the library:

/Physical Modeling/Fluids/Fluid Network Interfaces/Interface (G-MA)

Description

Block Interface (G-MA) It is a connection between the flows of a gas network and a humid air network. The pressure, temperature, and mass flow rate at the boundary are equal. The block does not transfer the properties of the liquid to each network across the border. To preserve the properties of the liquid, make sure that the unit Gas Properties (G) and the block Moist Air Properties (MA) they have the same settings. When moist air exits the MA port, the unit assigns parameter values to it. Interface relative humidity, Interface trace gas mass fraction and Interface mass ratio of water droplets to moist air or the values of the input signals. However, when humid air enters the MA port, the unit stores the values of the variables in the humid air flow.

You can choose whether to maintain constant humidity, the ratio of water droplets and the amount of impurity gas at the boundary, or set them using the ports W or Tw, D and TG, respectively.

Conservation of mass and momentum

The mass flow rate is maintained:

where

— mass flow of gas to the port G;
— the mass flow of moist air into the port MA.

The unit maintains equal pressures and temperatures in the ports, such that:

Energy conservation

Saving energy at the border:

where

— energy flow to port G;
— energy flow to the port MA;
— specific enthalpy in the port G;
— specific enthalpy in the port MA;
— the flow rate in the port G;
— the flow rate in the port MA.

For a given cross-sectional area of the hole , the block defines and how:

where

— specific volume in the port G;
— specific volume in the port MA:

Universal gas mixture constant At the boundary, it is a function of the fluid on both sides:

where

— specific gas constant of dry air;
— specific gas constant of water vapor;
— specific gas constant of impurity gases;
— specific humidity at the border. The block determines this value when the stream exits the MA port based on the parameter settings.:
- When the check box Provide input signal for interface humidity removed, the block calculates based on the method specified in the parameter Interface humidity specification.
- When the checkbox is selected Provide input signal for interface humidity installed, the block calculates based on the input value on port W or on port Tw.
— the mass fraction of impurity gas at the boundary. The block determines this value when the stream exits the MA port based on the parameter settings.:
- When the checkbox is selected Provide input signal for interface trace gas removed, the block calculates based on the parameter value Interface trace gas mass fraction or Interface trace gas mole fraction.
- When the checkbox is selected Provide input signal for interface trace gas installed, the block calculates based on the input value on the TG port.

Ports

Conserving

# G — gas port
gas

Details

A non-directional port connected to gas at the border.

Program usage name

gas_port

# MA — humid air port
humid air

Details

A non-directional port connected to humid air at the border.

Program usage name

moist_air_port

Input

# Tw — temperature, K
scalar

Details

The port that determines the temperature using a wet thermometer at the border, in K.

Dependencies

To use this port, check the box Provide input signal for interface humidity, and for the parameter Interface humidity specification set the value Wet-bulb temperature.

Data types	`Float64`
Complex numbers support	No

# TG — impurity gas
scalar

Details

The port that determines the proportion of impurity gas at the border.

Dependencies

To use this port, check the box Provide input signal for interface trace gas.

Data types	`Float64`
Complex numbers support	No

# W — humidity, dimensionless value
scalar

Details

The port that determines the humidity at the border.

Dependencies

To use this port, check the box Provide input signal for interface humidity, and for the parameter Interface humidity specification set the value Relative humidity, Specific humidity, Mole fraction or Humidity ratio.

Data types	`Float64`
Complex numbers support	No

# D — mass ratio of water droplets, dimensionless value
scalar

Details

A port that determines the mass ratio of water droplets and moist air at the border.

Dependencies

To use this port, check the box Provide input signal for interface water droplets.

Data types	`Float64`
Complex numbers support	No

Parameters

Main

# Inputs outside valid range — an option for monitoring or managing input data outside the acceptable range
Limit to valid values | Error

Details

Monitor or monitor invalid inputs. If the value is selected Limit to valid values, then the block saturates the input values within the set boundaries. If the value is selected Error, then the simulation stops when the block receives invalid input values.

Values	`Limit to valid values` \| `Error`
Default value	`Limit to valid values`
Program usage name	`assert_action`
Evaluatable	No

# Provide input signal for interface trace gas — the option of controlling the impurity gas at the border

Details

If this option is unchecked, the unit keeps the impurity gas constant at the boundary. If this option is selected, the impurity gas is set via the TG port.

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

# Interface specific humidity — specific humidity at the boundary

Details

Specific humidity at the border. The unit uses this value to calculate humidity.

Dependencies

To use this option, uncheck the box. Provide input signal for interface humidity, and for the parameter Interface humidity specification set the value Specific humidity.

Default value	`0.01`
Program usage name	`x_w_const`
Evaluatable	Yes

# Provide input signal for interface humidity — humidity control option at the border

Details

If this option is unchecked, the unit maintains constant humidity at the border. If this option is selected, the humidity is set via the W port.

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

# Interface mass ratio of water droplets to moist air — the ratio of water droplets to moist air at the boundary

Details

The ratio of the mass of water droplets and moist air at the boundary.

Dependencies

To use this option, uncheck the box. Provide input signal for interface water droplets.

Default value	`0.0`
Program usage name	`r_d_const`
Evaluatable	Yes

# Interface water vapor mole fraction — molar fraction of water vapor at the boundary

Details

The molar fraction of water vapor at the interface. The unit uses this value to calculate humidity.

Dependencies

To use this option, uncheck the box. Provide input signal for interface humidity, and for the parameter Interface humidity specification set the value Mole fraction.

Default value	`0.01`
Program usage name	`y_w_const`
Evaluatable	Yes

# Interface relative humidity — relative humidity at the border

Details

Relative humidity at the border. The unit uses this value to calculate humidity.

Dependencies

To use this option, uncheck the box. Provide input signal for interface humidity, and for the parameter Interface humidity specification on Relative humidity.

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

Details

The temperature of the wet thermometer at the interface. The unit uses this value to calculate humidity.

Dependencies

To use this option, uncheck the box. Provide input signal for interface humidity, and for the parameter Interface humidity specification set the value Wet-bulb temperature.

Units	`K` \| `degC` \| `degF` \| `degR` \| `deltaK` \| `deltadegC` \| `deltadegF` \| `deltadegR`
Default value	`287 K`
Program usage name	`T_wb_const`
Evaluatable	Yes

# Cross-sectional area at ports G and MA — the cross-sectional area of the openings for gas and humid air
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 openings for gas and humid air.

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

# Interface humidity ratio — humidity coefficient at the boundary

Details

Humidity coefficient at the boundary. The unit uses this value to calculate humidity.

Dependencies

To use this option, uncheck the box. Provide input signal for interface humidity, and for the parameter Interface humidity specification set the value Humidity ratio.

Default value	`0.01`
Program usage name	`HR_const`
Evaluatable	Yes

# Interface humidity specification — humidity parameterization
Relative humidity | Specific humidity | Mole fraction | Humidity ratio | Wet-bulb temperature

Details

Choose how to calculate humidity: using relative humidity, specific humidity, molar fraction, humidity coefficient, or the temperature of a wet thermometer.

Values	`Relative humidity` \| `Specific humidity` \| `Mole fraction` \| `Humidity ratio` \| `Wet-bulb temperature`
Default value	`Relative humidity`
Program usage name	`moisture_type`
Evaluatable	No

# Relative humidity at saturation — relative humidity at the saturation point

Details

Relative humidity at the saturation point.

Default value	`1.0`
Program usage name	`RH_ws`
Evaluatable	Yes

# Interface trace gas mole fraction — molar fraction of impurity gas at the boundary

Details

The molar fraction of the impurity gas at the boundary.

Dependencies

To use this option, uncheck the box. Provide input signal for interface trace gas, and for the parameter Interface trace gas specification set the value Mole fraction.

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

# Interface trace gas specification — parameterization of impurity gas
Mass fraction | Mole fraction

Details

Choose how to parameterize the impurity gas at the boundary: using a mass fraction or a molar fraction.

Values	`Mass fraction` \| `Mole fraction`
Default value	`Mass fraction`
Program usage name	`trace_gas_type`
Evaluatable	No

# Provide input signal for interface water droplets — water droplet control option at the border

Details

If this option is unchecked, the ratio of water droplets to moist air at the boundary is set using the parameter Interface mass ratio of water droplets to moist air. If this option is selected, the ratio of water droplets to moist air at the border is set via port D.

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

# Interface trace gas mass fraction — mass fraction of impurity gas at the boundary

Details

The mass fraction of impurity gas at the boundary.

Dependencies

To use this option, uncheck the box. Provide input signal for interface trace gas and set for the parameter Interface trace gas specification meaning Mass fraction.

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