Controlled Pressure Difference Source (2P)
The source of the pressure drop.
blockType: AcausalFoundation.TwoPhaseFluid.Sources.PressureDifference
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Controlled Pressure Difference Source (2P) Path in the library: |
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Pressure Difference Source (2P) Path in the library: |
Description
Block Controlled Pressure Difference Source (2P) It is an ideal source of mechanical energy in a two-phase liquid network. The source can maintain a constant pressure drop at its ports regardless of the mass flow through the source. At the same time, there is no hydraulic resistance and no heat exchange with the environment.
Ports A and B represent the input and output of the source. If the check box is selected Controlled, then the pressure drop is controlled by the input scalar signal on port P. If the check box Controlled if not set, then the pressure drop is constant and is set by the parameter Pressure differential. A positive differential pressure value means that the pressure at port B is greater than the pressure at port A.
Conservation of mass
The volume of liquid in the source is considered negligible and is ignored in the model. There is no accumulation of liquid between the ports, so the sum of all mass flow rates entering the source should be zero.:
where — mass flow rate at the source through the appropriate port. The unit accepts the input of the mass flow in port A. If the mass flow value at port A is positive, then the flow is directed from port A to port B.
Energy conservation
By default, the source maintains the set flow rate by performing isentropic work on the incoming liquid, although the block provides the option to ignore this term. If the model takes into account the speed at which the source performs work, then it is equal to the sum of the energy flows through the ports.:
where indicates the flow of energy to a source through a port or through work. The energy flow due to work is equal to the power generated by the source. Its value is calculated from the values of the specific total enthalpy at the ports:
Specific total enthalpy defined as
where
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the asterisk indicates the port (A or B);
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— specific internal energy;
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— pressure;
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— the area of the stream.
The value of the specific internal energy is determined taking into account the fact that the work performed by the source is isentropic. Then the specific entropy, which is a function of the specific internal energy, should have the same value at ports A and B:
where — specific entropy. If the check box Isentropic power added removed, the specific total enthalpies in the ports have the same value ( ), and the work done by the source is zero ( ).
Ports
Input
#
P
—
differential pressure control signal, Pa
scalar
Details
The input value of the pressure drop at the source.
Dependencies
To use this port, check the box Controlled.
| Data types |
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| Complex numbers support |
I don’t |
Conserving
#
A
—
Input to the source
two-phase liquid
Details
Non-directional port of two-phase liquid. If the flow rate is positive, the liquid flows from port A to port B.
| Program usage name |
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#
B
—
exit from the source
two-phase liquid
Details
Non-directional port of two-phase liquid. If the flow rate is positive, the liquid flows from port A to port B.
| Program usage name |
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Parameters
Parameters
# Controlled — is the pressure drop set by the input signal
Details
Determines how the pressure drop will be set:
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If the flag is checked, the pressure drop is set by the input signal P;
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If the flag is unchecked, the constant pressure drop is set by the parameter Pressure differential.
| Default value |
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| Program usage name |
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| Evaluatable |
No |
# Isentropic power added — is the source doing the job
Details
Sets whether the source is working with the liquid flow.:
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If the check box is selected, the source performs isentropic work on the liquid to maintain the set 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.
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If unchecked, the source does not perform any work on the flow, neither adding nor subtracting energy, regardless of the pressure drop created by the source. Use this option to set the desired flow mode at the system entrance without affecting the flow temperature.
| Default value |
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| Program usage name |
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| 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 |
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| Default value |
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| Program usage name |
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| 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 |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Pressure differential —
constant pressure drop through the source
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 at the source ports.
Dependencies
To use this option, uncheck the box. Controlled.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |