Valve (ProBal)

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Navigation: Main Page -> Models -> Pressure Changing Models


General Description

The valve model will add pressure drop to the stream or operates at a specified pressure.

Diagram

Valve image001.gif

The diagram shows the default drawing of the Valve, 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 Input / Output No. of Connections Description
    Min Max  
Input In 1 1 Input stream to valve.
Output Out 1 1 Output stream from valve.

Model Theory

The valve is a constant enthalpy process.

Step 1) Enthalpy can be calculated from the inlet conditions.

Step 2) Outlet temperature can be calculated from enthalpy and outlet pressure.

Data Sections

The default access window consists of four sections,

  1. The first tab has the same name as the model tag, contains the main configuration information relating to the unit.
  2. Optional tab Vapour Liquid Equilibrium (VLE)
  3. The section, Info, fully described in Info Tab Page Section.
  4. The section, Links, contains a summary table for all the input and output streams. See Links Table.
  5. The last section is the Audit. See Model Examples for enthalpy calculation Examples.


Tag / Symbol
Input / Calc
Options
Description/Calculated Variables

Common Data on First Tab Page

Requirements

PressureMethod

List Box

None

No pressure change across the unit.

Drop

The user specifies a pressure drop. Therefore, Pout = Pin - Pdrop

Fixed

The user specifies a fixed outlet pressure from the unit.

Atmos

The outlet pressure from the unit is set to atmospheric pressure.

PDrop

Input

 

The required pressure drop. Visible if the Drop method is selected.

PRqd

Input

 

The required outlet pressure. Visible if the Fixed method is selected.

VLEquilibrium

List Box

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

Qm

Calc

 

The mass flow rate through the unit.

Ti

Calc

 

The inlet temperature to the unit.

To

Calc

 

The outlet temperature from the unit.

Pi

Calc

 

The inlet pressure to the unit.

dP

Calc

 

The pressure change across the unit.

Po

Calc

 

The outlet pressure from the unit.

Vfi

Calc

 

The Inlet vapour fraction.

Vfo

Calc

 

The outlet vapour fraction.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

 

DLL:

Basic1.dll

Units/Links

Process: Piping: Valve(1)

or

Group:

Mass Transfer

Units/Links

Process: Piping: Valve(1)

See Project Configuration for more information on adding models to the configuration file.


Insert into Project

 

Insert Unit

Process

Piping

Valve(1)

See Insert Unit for general information on inserting units.