Controlled Mass Flow Rate Source (G)

A source of mass or volume flow.

blockType: AcausalFoundation.Gas.Sources.FlowRate

Controlled Mass Flow Rate Source (G)

Path in the library:

/Physical Modeling/Fundamental/Gas/Sources/Controlled Mass Flow Rate Source (G)

Controlled Volumetric Flow Rate Source (G)

Path in the library:

/Physical Modeling/Fundamental/Gas/Sources/Controlled Volumetric Flow Rate Source (G)

Mass Flow Rate Source (G)

Path in the library:

/Physical Modeling/Fundamental/Gas/Sources/Mass Flow Rate Source (G)

Volumetric Flow Rate Source (G)

Path in the library:

/Physical Modeling/Fundamental/Gas/Sources/Volumetric Flow Rate Source (G)

Description

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

A positive flow rate causes gas to flow from port A to port B. If the parameter Controlled source type If enabled, the mass or volume flow rate is controlled by an input signal on the M or V ports, respectively. If the parameter Controlled source type if turned off, the mass or volume flow rate will be constant and set by the parameters Mass flow rate or Volumetric flow rate accordingly.

Volumetric flow and mass flow are related by the expression

where

— mass flow rate from port A to port B, kg/s;
and — densities at ports A and B, respectively, kg/m³;
— volumetric flow rate, m3/s.

The flow type is switched using the parameter Flow type, which by default has the value Mass, which corresponds to the mass flow rate. To switch to volume flow, select the value Volumetric.

You can choose whether the source does work with the gas flow.:

If the source is isentropic (the check box is selected Isentropic power added), then the isentropic ratio depends on the model of gas properties.

The gas model The equation

The ideal gas

Semi-ideal gas

Real gas

The power given to the gas flow is based on the specific total enthalpy associated with the isentropic process.
If the source is not doing any work (parameter Isentropic power added off), then the basic equation is written based on the fact that the specific total enthalpy is the same on both sides of the source. This is equally true for all three models of gas properties.

Power supplied to the gas stream .

The gas model	The equation
The ideal gas
Semi-ideal gas
Real gas

The following notation is used in the equations:

— specific heat capacity at constant pressure, J/(kg*K);
— specific enthalpy, J;
— mass flow rate, kg/s (the flow rate associated with the port is positive when gas enters the unit through this port);
— pressure, Pa;
— specific gas constant, J/(mol*K);
— specific entropy, J/(kg*K);
— temperature, K;
— flow rate, m/s;
— the coefficient of compressibility;
— the power supplied to the gas flow through the source, W.

The A and B indexes indicate the corresponding port.

Assumptions and limitations

There are no irreversible losses.
There is no heat exchange with the environment.

Ports

Conserving

# A — Source Input
gas

Details

Gas inlet port. A positive mass flow rate causes gas to flow from port A to port B.

Program usage name

inlet

# B — source outlet
gas

Details

Gas outlet port. A positive mass flow rate causes gas to flow from port A to port B.

Program usage name

outlet

Input

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

Details

The input port that determines the mass flow of gas through the source.

Dependencies

To use this port, check the box Controlled source type and set for the parameter Flow type value Mass.

Data types	`Float64`
Complex numbers support	I don’t

# V — the signal for setting the volumetric flow rate, m3/s
scalar

Details

The input port that determines the volume flow of gas through the source.

Dependencies

To use this port, check the box Controlled source type and set for the parameter Flow type value Volumetric.

Data types	`Float64`
Complex numbers support	I don’t

Parameters

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

Details

Determines how the flow rate will be set:

If this option is selected, the mass or volume flow rate is set by the input signals M or V, respectively.
If this option is not selected, then the mass or volume flow rate is constant and is set by the parameters Mass flow rate or Volumetric flow rate accordingly.

Default value	`—`
Program usage name	`controlled`
Evaluatable	No

# Flow type — the mass or volume flow is set
Mass | Volumetric

Details

Determines which type of flow is set:

Mass — the mass flow rate is set.
Volumetric — the volume flow is set.

Values	`Mass` \| `Volumetric`
Default value	`—`
Program usage name	`flow_type`
Evaluatable	No

Details

Constant mass flow of gas through the source.

Dependencies

Used if the parameter Controlled source type disabled for the parameter as well Flow type the value is set Mass.

Units	`kg/s` \| `kg/hr` \| `kg/min` \| `g/hr` \| `g/min` \| `g/s` \| `t/hr` \| `lbm/hr` \| `lbm/min` \| `lbm/s`
Default value	`0.0 kg/s`
Program usage name	`mdot_const`
Evaluatable	Yes

# Volumetric flow rate — constant volume flow through the source
m^3/s | mm^3/s | cm^3/s | m^3/hr | m^3/min | l/hr | l/min | l/s | gal/hr | gal/min | gal/s | ft^3/hr | ft^3/min | ft^3/s

Details

Constant volume flow of gas through the source.

Dependencies

Used if the parameter Controlled source type disabled for the parameter as well Flow type the value is set Volumetric.

Units	`m^3/s` \| `mm^3/s` \| `cm^3/s` \| `m^3/hr` \| `m^3/min` \| `l/hr` \| `l/min` \| `l/s` \| `gal/hr` \| `gal/min` \| `gal/s` \| `ft^3/hr` \| `ft^3/min` \| `ft^3/s`
Default value	`0.0 m^3/s`
Program usage name	`Vdot_const`
Evaluatable	Yes

# Specified flow rate conditions — should the volume flow be calculated under standard or actual operating conditions
Actual conditions | Standard conditions

Details

Select whether the source calculates the flow rate under actual operating conditions or at standard pressure and temperature.:

Actual conditions — the source calculates the volumetric flow rate using the gas density under the actual operating conditions of the system.
Standard conditions — the source calculates the volumetric flow rate using the gas density under standard conditions. When this option is selected, additional parameters are available that allow you to set the standard pressure and temperature.

Dependencies

To use this parameter, set for the parameter Flow type meaning Volumetric.

Values	`Actual conditions` \| `Standard conditions`
Default value	`Actual conditions`
Program usage name	`volumetric_flow_conditions`
Evaluatable	No

# Standard pressure — gas pressure under standard 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

Gas pressure under standard conditions.

Dependencies

To use this parameter, set for the parameter Specified flow rate conditions meaning Standard conditions.

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	`0.101325 MPa`
Program usage name	`p_standard`
Evaluatable	Yes

Details

Gas temperature under standard conditions.

Dependencies

To use this parameter, set for the parameter Specified flow rate conditions meaning Standard conditions.

Units	`K` \| `degC` \| `degF` \| `degR` \| `deltaK` \| `deltadegC` \| `deltadegF` \| `deltadegR`
Default value	`20.0 degC`
Program usage name	`T_standard`
Evaluatable	Yes

# Isentropic power added — is the source doing the job

Details

Sets whether the source is working with the gas flow.:

If this option is selected, the source performs isentropic work with the gas to maintain the set mass flow rate regardless of the pressure drop. Use this parameter to represent the ideal pump or compressor and to properly account for energy consumption and output, especially in closed-loop systems.
If this option is unchecked, the source does not perform any work with the flow, neither adding nor subtracting power, regardless of the mass flow rate generated by the source. Use this option to set the desired flow mode at the system entrance without affecting the flow temperature.

Default value	`true (switched on)`
Program usage name	`isentropic`
Evaluatable	No

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

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	`inlet_area`
Evaluatable	Yes

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

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	`outlet_area`
Evaluatable	Yes

Useful links

Modeling of gas systems

Examples

Simulation of a ventilation system in a building with a temperature control system