Pressure Difference Source (MA)
The source of the pressure drop.
blockType: AcausalFoundation.MoistAir.Sources.PressureDifference
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Controlled Pressure Difference Source (MA) Path in the library: |
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Pressure Difference Source (MA) Path in the library: |
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Description
Block Pressure Difference Source (MA) It is an ideal source of mechanical energy in a humid air network. The source can maintain a constant or variable pressure drop at its ports regardless of the mass flow through the source. There is no gas resistance and no heat exchange with the environment. A positive pressure drop value means that the pressure at port B is greater than the pressure at port A.
Conservation of mass
where
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— mass consumption;
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Lower indexes and specify ports A and B respectively;
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Lower indexes , and They indicate the properties of water vapor, gas impurities, and water droplets, respectively.
Energy balance
where and — energy flows through ports A and B respectively.
If the source is not doing any work (for the disabled parameter Isentropic power added), then .
If the source is isentropic (for the enabled parameter Isentropic power added), then:
where
Enthalpy of mixtures, and , are limited by the isentropy dependence, i.e. there is no change in entropy:
The value set by the parameter Pressure differential or the input signal of the P source, has the form:
Ports
Conserving
#
A
—
source input
moist air
Details
Wet air port. Positive pressure drop causes the pressure at port B to be greater than the pressure at port A.
| Program usage name |
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#
B
—
source input
moist air
Details
Wet air port. Positive pressure drop causes the pressure at port B to be greater than the pressure at port A.
| Program usage name |
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Input
#
P
—
differential pressure setting signal, Pa
scalar
Details
An input port that determines the wet air pressure differential at the source. A positive signal at port P causes the pressure at port B to be greater than the pressure at port A.
Dependencies
To use this port, select the checkbox Controlled source.
| Data types |
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| Complex numbers support |
No |
Parameters
Main
#
Pressure differential —
constant pressure drop
Pa | uPa | hPa | kPa | MPa | GPa | kgf/m^2 | kgf/cm^2 | kgf/mm^2 | mbar | bar | kbar | atm | ksi | psi | mmHg | inHg
Details
The pressure drop of the moist air mixture at the source ports.
Dependencies
To use this parameter, uncheck Controlled source.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# 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 differential pressure. Use this parameter to represent an ideal pump or compressor and to properly account for energy input and output, especially in closed loop systems.
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If unchecked, the source does not perform any work on the flow, either adding or removing power, regardless of the pressure drop generated by the source. Use this option to set the desired flow condition upstream of the system 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 B —
cross-sectional area normal to the flow path at the port B
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac
Details
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 |
#
Cross-sectional area at port A —
cross-sectional area normal to the flow path at the port A
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac
Details
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 |
# Controlled source — whether the differential pressure is set by the input signal
Details
Defines how the differential pressure is set:
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If the checkbox is selected, the differential pressure is set by the input signal P.
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If unchecked, the constant differential pressure is set by the parameters Pressure differential.
| Default value |
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| Program usage name |
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| Evaluatable |
No |