Gas Pump

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Navigation: Models ➔ Pressure Changing Models ➔ Gas Pump


General Description

The gas pump model will add pressure boost to the stream or operates at a specified pressure.

Diagram

Models-Pump-Image001.gif

The diagram shows the default drawing of the Gas Pump, with the required connecting streams. The unit will not operate unless all of the above streams are connected.

The physical location of the connections is not important, the user may connect the streams to any position on the drawing.

Inputs and Outputs

Label Required
Optional
Input
Output
Number of Connections Description
Min Max.
Input Required In 1 1 Input stream to pump.
Output Required Out 1 1 Output stream from pump.

Model Theory

From the first law of thermodynamics, the energy balance is:

[math]\mathbf{\mathit{Work=Enthalpy_{in}-Enthalpy_{out}}}[/math]

From the second law of thermodynamics:

[math]\mathbf{\mathit{Entropy_{in} = Entropy_{out}}}[/math]

Calculating Work:

Step 1) Enthalpy and Entropy in is calculated from the inlet stream Temperature and Pressure.

Step 2) Outlet Temperature and Enthalpy is calculated based on the Entropy and outlet pressure.

Step 3) Work is calculated from the difference in enthalpy.

Assumptions

  1. The process is in steady state and steady flow.
  2. The process is adiabatic.
  3. The change in Potential and Kinetics energy is ignored.
  4. Process is reversible and adiabatic

Data Sections

Summary of Data Sections

  1. GasPump1 tab - Contains general information relating to the unit.
  2. VLE - Optional tab, only visible if the VLEquilibrium is enabled in the Evaluation Block.
  3. Info tab - Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.
  4. Links tab, contains a summary table for all the input and output streams.
  5. Audit tab - Contains summary information required for Mass and Energy balance. See Model Examples for enthalpy calculation Examples.

Gas Pump Page

Unit Type: GasPump1 - The first tab page in the access window will have this name.

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
Tag Display This name tag may be modified with the change tag option.
Condition Display OK if no errors/warnings, otherwise lists errors/warnings.
ConditionCount Display The current number of errors/warnings. If condition is OK, returns 0.
GeneralDescription / GenDesc Display This is an automatically generated description for the unit. If the user has entered text in the 'EqpDesc' field on the Info tab (see below), this will be displayed here.
If this field is blank, then SysCAD will display the unit class ID.

Requirements

PressMethod None No pressure change
Boost The user specifies a pressure increase. Therefore, Pout = Pin + Pboost
Fixed The user specifies a fixed outlet pressure from the unit.
PressBoostReqd / PBoostReqd Input The required pressure increase. Visible if the Boost method is selected.
PressureReqd / P_Reqd Input The required outlet pressure. Visible if the Fixed method is selected.
VLEquilibrium Off Vapour Liquid Equilibrium is off.
On Vapour Liquid Equilibrium (VLE) is enabled. The associated section, VLE becomes visible and may be configured.
Note: This option may automatically adjust the species make-up in Qo.

Results

Work Calc The work done.
MassFlow / Qm Calc The total mass of material flowing through the gas pump.
TemperatureIn / Ti Calc The temperature of material at the inlet of the gas pump.
TemperatureOut / To Calc The temperature of material at the outlet of the gas pump.
PressureIn / Pi Calc The actual pressure at the inlet of the gas pump.
PressChange / dP Calc The pressure change in the gas pump.
PressureOut / Po Calc The actual pressure at the outlet of the gas pump.
DensityIn / Rhoi Calc The density of material at the inlet of the gas pump.
DensityOut / Rhoo Calc The density of material at the outlet of the gas pump.
VapourFracIn / Vfi Calc Vapour Mass Fraction at the inlet of the gas pump.
VapourFracOut / Vfo Calc Vapour Mass Fraction at the outlet of the gas pump.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

  DLL:
Piping1.dll
Units/Links Piping: GasPump - General
or Group:
Mass Transfer
Units/Links Piping: GasPump - General

See Model Selection for more information on adding models to the configuration file.


Insert into Project

  Insert Unit Piping GasPump - General

See Insert Unit for general information on inserting units.