Controlled Pressure Difference Source (G)
Source of differential pressure.
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Description
The Pressure Difference Source (G) unit represents an ideal source of mechanical energy in a gas network. The source can maintain a constant pressure differential at its ports regardless of the mass flow rate through the source. There is no gas resistance and no heat exchange with the environment. A positive value of the pressure drop causes the pressure at port B to be greater than the pressure at port A.
If Controlled source type is enabled, the differential pressure is controlled by the input scalar signal at port P. If Controlled source type is disabled, the pressure drop is constant and is set by Pressure difference, Pa.
You can choose whether or not the source performs gas flow operation:
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If the source is isentropic (parameter Isentropic power added is on), the isentropic ratio depends on the gas property model.
Gas model Equation Ideal gas
Semi-ideal gas
Real gas
The power given to the gas flow is based on the specific total enthalpy associated with the isoentropic process.
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If the source does no work (the Isentropic power added parameter is off), the basic equation is written assuming that the specific total enthalpy is the same on both sides of the source. This is equally true for all three gas property models.
Power applied to the gas flow .
The following notations are used in the equations:
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- specific heat capacity at constant pressure, J/(kg∙K);
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- specific enthalpy, J;
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- mass flow rate, kg/s (the flow rate associated with a port is positive when gas enters the unit through that port);
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- pressure, Pa;
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- universal gas constant, J/(mol∙K);
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- specific entropy, J/(kg∙K);
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- temperature, K;
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- flow velocity, m/s;
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- compressibility coefficient;
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- power supplied to the gas flow through the source, W.
The indices A and B indicate the corresponding port.
Ports
Parameters
Controlled source type - whether the differential pressure is set by the input signal
On (by default) | Off
Defines how the differential pressure will be set:
-
on- the differential pressure is set by the P input signal. -
Disabled - constant pressure drop is set by the parameter Pressure difference, Pa.
Isentropic power added - whether the source is performing work
On (By default) | Off - constant pressure difference set by parameter Pressure difference Pa
Sets whether the source performs work on the gas flow:
-
on- the source performs isoentropic gas work to maintain a given mass flow rate regardless of pressure drop. Use this parameter to represent an ideal pump or compressor and to properly account for energy input and output, especially in closed loop systems. -
`Disabled' - the source does not perform any work on the flow, either adding or taking away power, regardless of the mass flow rate generated by the source. Use this option to set the desired flow regime at the system inlet without affecting the flow temperature.
Cross-sectional area at port A, m² - cross-sectional area normal to the flow path at port A
0.01 m² (by default).
Cross-sectional area normal to the flow path at port A.
Cross-sectional area at port B, m² - cross-sectional area normal to the flow path at port B.
`0.01 m² (by default).
Cross-sectional area normal to the flow path at port B.
Pressure difference, Pa - constant pressure difference
0 (By default).
Gas pressure difference at the source ports.
Dependencies
Used when Controlled source type is disabled.