Valve

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Navigation: Models ➔ Pressure Changing Models ➔ Valve 1

Valve 1 in Steady State and Dynamic Transfer Push Mode Valve 1 in Dynamic Transfer Pull Mode

Related Links: Setting up Transfer Pull Network, Dynamic Transfer Simulation Mode


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 Required
Optional
Input
Output
Number of Connections Description
Min Max.
Input Required In 1 1 Input stream to valve.
Output Requered 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

Summary of Data Sections

  1. Valve-1 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.

Valve Page

Unit Type: Valve-1 - 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 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.
PressDropReqd / PDropReqd Input The required pressure drop. Visible if the Drop 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

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

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

  DLL:
Piping1.dll
Units/Links Piping: Valve(1)
or Group:
Mass Transfer
Units/Links Piping: Valve(1)

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


Insert into Project

  Insert Unit Piping Valve(1)

See Insert Unit for general information on inserting units.