Engee documentation

Controlled Reservoir (MA)

Boundary conditions for a network of moist air at time-varying pressure, temperature, humidity and impurity gas levels.

blockType: AcausalFoundation.MoistAir.Elements.ControlledReservoir

controlled reservoir (ma)

Path in the library:

/Physical Modeling/Fundamental/Moist Air/Elements/Controlled Reservoir (MA)

Description

The block Controlled Reservoir (MA) sets the controlled boundary conditions in the humid air network. The volume of moist air inside the tank is assumed to be infinite. Therefore, the flow is assumed to be quasi-stationary. The humid air leaves the tank at a given pressure, temperature, specific humidity and admixture gas mass fraction. The moist air enters the tank at tank pressure, but the temperature, specific humidity and mass fraction of impurity gas are determined by the upstream moist air network.

The pressure, temperature, moisture and impurity gas quantities in the tank are set by control signals at the P, T, W/Tw and G ports respectively. The input signals are limited by their allowable ranges. For moisture quantity, the allowable range is from zero to saturation or 100% water vapour. For the amount of impurity gas, the allowable range is from zero to either the fraction remaining after water vapour or 100% impurity gas.

You can specify humidity as one of the options:

  • Relative Humidity, ;

  • Specific humidity, ;

  • Molar fraction of water vapour, ;

  • Humidity coefficient, ;

  • Humid thermometer temperature, .

You can specify impurity gas as one of the options:

  • Mass fraction of impurity gas, ;

  • Molar fraction of impurity gas, .

The amount of moisture and impurity gases are related to each other as follows:

,

,

,

,

,

,

where

  • - pressure;

  • - is the universal gas constant.

The indices , and indicate the properties of dry air, water vapour and residual gases respectively. The lower index indicates the water vapour saturation level.

The block implicitly calculates the wet-bulb temperature using the following equation:

,

where

  • - temperature;

  • - is the wet-bulb temperature;

  • - specific humidity;

  • - mass fraction of impurity gases;

  • - saturation specific humidity at wet-bulb temperature;

  • - specific enthalpy of dry air;

  • - specific enthalpy of dry air at wet-bulb temperature;

  • - specific enthalpy of impurity gas;

  • - specific enthalpy of impurity gas at wet thermometer temperature;

  • - specific enthalpy of water vapour;

  • - specific enthalpy of water vapour at wet thermometer temperature;

  • - specific enthalpy of vaporisation of water vapour at wet thermometer temperature.

Ports

Conserving

# A — humid air port
humid air

Details

Moist air port, corresponds to the tank inlet.

Program usage name

port

Input

# T — temperature, K
scalar

Details

An input port that determines the temperature value in the tank.

Data types

Float64.
Complex numbers support

No

# P — pressure, Pa
scalar

Details

An input port that determines the pressure value in the tank.

Data types

Float64.
Complex numbers support

No

# W — humidity
scalar

Details

Input port that defines the moisture value in the tank. The method of setting is defined by the parameters Reservoir moisture specification.

Dependencies

To use this port, set the Reservoir moisture specification parameters to a value other than . Wet-bulb temperature.

Data types

Float64.
Complex numbers support

No

# G — impurity gas level
scalar

Details

Input port that defines the value of the amount of impurity gases in the tank. The method of setting is defined by the parameters Reservoir trace gas specification.

Data types

Float64.
Complex numbers support

No

# Tw — wet bulb temperature setting, K
scalar

Details

An input port that monitors temperature by wet tank thermometer.

Dependencies

To use this port, set the Reservoir moisture specification parameters to Wet-bulb temperature.

Data types

Float64.
Complex numbers support

No

Parameters

Parameters

# Reservoir moisture specification — moisture measurement method
Relative humidity | Specific humidity | Water vapor mole fraction | Humidity ratio | Wet-bulb temperature

Details

Sets the measurement method:

  • Relative humidity - W port signal equals relative humidity.

  • Specific humidity - The signal on the W port equals the specific humidity.

  • Water vapor mole fraction - signal at port W is equal to molar fraction of humidity.

  • Humidity ratio - the signal on the W port is equal to the moisture content ratio.

  • Wet-bulb temperature - signal on the W port sets the temperature of the moisture thermometer.

Values

Relative humidity | Specific humidity | Water vapor mole fraction | Humidity ratio | Wet-bulb temperature
Default value

Relative humidity
Program usage name

moisture_type
Evaluatable

No

# Reservoir trace gas specification — method of measuring the amount of impurity gases
Mass fraction | Mole fraction

Details

Sets the method for measuring the composition of impurity gases:

  • Mass fraction - the signal on the G port is equal to the mass fraction of impurity gases.

  • Mole fraction - The signal on the G port is equal to the molar fraction of impurity gases.

Values

Mass fraction | Mole fraction
Default value

Mass fraction
Program usage name

trace_gas_type
Evaluatable

No

# Relative humidity at saturation — Relative humidity above which condensation occurs

Details

Relative humidity above which condensation occurs. The amount of moisture must be less than the saturation level.

Default value

1.0
Program usage name

RH_saturation
Evaluatable

Yes

# Cross-sectional area at port A — area normal to the flow direction at the tank inlet
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

The cross-sectional area of the tank inlet in the direction normal to the wet air flow path.

Units

m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2
Default value

0.01 m^2
Program usage name

port_area
Evaluatable

Yes