Engee documentation

Volumetric Flow Rate Source (MA)

A source of mass or volumetric flow.

blockType: AcausalFoundation.MoistAir.Sources.FlowRate

controlled mass flow rate source (ma)

Controlled Mass Flow Rate Source (MA)

Path in the library:

/Physical Modeling/Fundamental/Moist Air/Sources/Controlled Mass Flow Rate Source (MA)

controlled volumetric flow rate source (ma)

Controlled Volumetric Flow Rate Source (MA)

Path in the library:

/Physical Modeling/Fundamental/Moist Air/Sources/Controlled Volumetric Flow Rate Source (MA)

mass flow rate source (ma)

Mass Flow Rate Source (MA)

Path in the library:

/Physical Modeling/Fundamental/Moist Air/Sources/Mass Flow Rate Source (MA)

volumetric flow rate source (ma)

Volumetric Flow Rate Source (MA)

Path in the library:

/Physical Modeling/Fundamental/Moist Air/Sources/Volumetric Flow Rate Source (MA)

Description

The Volumetric Flow Rate Source (MA) unit is an ideal source of mechanical energy in a humid air network. The source can maintain a given mass or volume flow rate regardless of pressure drop. There is no flow resistance and no heat exchange with the environment.

A positive flow rate causes moist air to flow from port A to port B. If the parameter Controlled source is enabled, the mass or volume flow rate is controlled by the input signal at ports M or V respectively. If Controlled source is disabled, the mass or volume flow rate is controlled by the parameters Mixture mass flow rate or Mixture volumetric flow rate respectively.

Volumetric flow rate and mass flow rate are related by the expression:

если ,

where

  • - is the mass flow rate from port A to port B;

  • and are densities at ports A and B, respectively;

  • - volumetric flow rate.

The lower indices and indicate the corresponding port.

Mass conservation

,

,

,

where

  • - mass flow rate;

  • Lower indices and are ports A and B respectively;

  • Lower indices and indicate water vapour and gas impurity properties respectively.

Energy balance

,

where and are the energy flow through ports A and B respectively.

If the source does not perform any work (for the parameter Isentropic power added) switched off, then .

If the source is isoentropic (for the parameter Isentropic power added) turned on, then:

,

where

;

.

The enthalpies of the mixtures, and , are bounded by isoentropic dependence, i.e., there is no entropy change:

.

If the parameters Flow type are set to the value of Mass and unchecked parameter Controlled source, the mass flow rate is determined by parameter Mixture mass flow rate and is equal to

.

Assumptions and limitations

  • There are no irreversible losses.

  • No heat exchange with the environment.

Ports

Conserving

# A — source input
moist air

Details

Moist Air Port. Positive mass flow rate causes moist air to flow from port A to port B.

Program usage name

inlet

# B — source output
`humid air

Details

Moist Air Port. Positive mass flow rate causes moist air to flow from port A to port B.

Program usage name

outlet

Input

# M — mass flow control signal, kg/s
scalar

Details

An input port that determines the mass flow rate of moist air through the source.

Dependencies

Used when the Controlled source checkbox is selected and the Flow type parameters are set to Mass.

Data types

Float64
Complex numbers support

No

# V — volume flow control signal, m3/sec
scalar

Details

An input port that determines the volumetric flow rate of moist air through the source.

Dependencies

Used when the Controlled source checkbox is selected and the Flow type parameters are set to Volumetric.

Data types

Float64
Complex numbers support

No

Parameters

Parameters

# Controlled source — whether the flow rate is set by the input signal

Details

Defines how the flow rate will be set:

  • If checked, the mass or volume flow rate is set by the input signals on the M or V ports, respectively.

  • If unchecked, the mass or volume flow rate is set by the parameters Mixture mass flow rate or Mixture volumetric flow rate, respectively.

Default value

—
Program usage name

controlled
Evaluatable

No

# Flow type — mass or volume flow rate
Mass | Volumetric

Details

Determines which type of flow rate is set:

  • Mass - mass flow rate is set.

  • Volumetric - The volume flow rate is set.

Values

Mass | Volumetric
Default value

—
Program usage name

flow_type
Evaluatable

No

# Isentropic power added — whether the source is doing isoentropic work

Details

Sets whether the source performs isoentropic work with moist air flow:

  • If checked, the source performs isoentropic work with moist air to maintain the specified mass or volumetric flow rate. Use this parameter to represent an ideal pump or compressor and to properly account for energy input and output, especially in closed loop systems.

  • If unchecked, the source does not perform any work on the flow, either adding or removing power, regardless of the mass or volumetric flow rate generated by the source. Use this option to set the desired flow condition upstream of the system without affecting the flow temperature.

Default value

true (switched on)
Program usage name

isentropic
Evaluatable

No

# Mixture mass flow rate — constant mass flow rate through the source
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)

Details

Constant mass flow rate of moist air through the source.

Dependencies

To use this parameter, clear the Controlled source checkbox and the Flow type parameters are set to Mass.

Units

kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)
Default value

0.0 kg/s
Program usage name

mdot_const
Evaluatable

Yes

# Mixture volumetric flow rate — constant volume flow rate through the source
m^3/s | m^3/h | cm^3/s | mm^3/s | ft^3/s | lpm | l/s | gpm | gal/s | gal/h

Details

Constant volumetric flow rate of moist air through the source.

Dependencies

To use this parameter, clear the Controlled source checkbox and set the Flow type parameters to . Volumetric.

Units

m^3/s | m^3/h | cm^3/s | mm^3/s | ft^3/s | lpm | l/s | gpm | gal/s | gal/h
Default value

0.0 m^3/s
Program usage name

Vdot_const
Evaluatable

Yes

# Specified flow rate conditions — conditions for calculating the volumetric flow rate
Actual conditions | Standard conditions

Details

Sets whether the source calculates the volumetric flow rate under actual operating conditions or at standard pressure, temperature, and relative humidity:

  • Actual conditions - the source calculates the volumetric flow rate using the density of moist air under actual system operating conditions.

  • Standard conditions - the source calculates the volumetric flow rate using the density of moist air under standard conditions.

Dependencies

To use this parameter, set the Flow type parameters to . Volumetric.

Values

Actual conditions | Standard conditions
Default value

Actual conditions
Program usage name

volumetric_flow_conditions
Evaluatable

No

# Standard pressure — Humid air pressure at standard conditions
Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar

Details

Humid air pressure at standard conditions.

Dependencies

To use this parameter, set the Flow type parameters to and the parameters to . Volumetric`and set the Specified flow rate conditions parameters to. `Standard conditions.

Units

Pa | GPa | MPa | atm | bar | kPa | ksi | psi | uPa | kbar
Default value

0.101325 MPa
Program usage name

p_standard
Evaluatable

Yes

# Standard temperature — Humid air temperature at standard conditions
K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR

Details

Humid air temperature at standard conditions.

Dependencies

To use this parameter, set the Flow type parameters to and the parameters to . Volumetric, and set the Specified flow rate conditions parameters to. Standard conditions.

Units

K | degC | degF | degR | deltaK | deltadegC | deltadegF | deltadegR
Default value

20.0 degC
Program usage name

T_standard
Evaluatable

Yes

# Standard relative humidity — relative humidity at standard conditions

Details

Relative air humidity at standard conditions.

Dependencies

To use this parameter, set the Flow type parameters to and the parameters to . Volumetric, and set the Specified flow rate conditions parameters to. Standard conditions.

Default value

0.65
Program usage name

RH_standard
Evaluatable

Yes

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

Details

Cross-sectional area normal to the flow path at port A.

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

inlet_area
Evaluatable

Yes

# Cross-sectional area at port B — cross-sectional area normal to the flow path at the port B
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2

Details

Cross-sectional area normal to the flow path at port B.

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

outlet_area
Evaluatable

Yes