joule thomson effect

sunilpatil · April 14, 2014, 03:36

Hello every one,
I am trying to simulate joule thomson effect by sending nitrogen vapor at high pressure (80 bar) in pipe with sudden expansion. for this which multiphase model i have to select in CFX (please see the attached image)

Thank you

JuPa · April 14, 2014, 07:16

Although not directly the same as what you're doing, Dr Thomas Frank from Ansys did the Edwards test for pressurised water (80 MPa) which suddenly decompressed to atmospheric pressure causing sudden flashing. Have a look at his papers to gauge how you'll get your problem to be numerically stable.

ghorrocks · April 14, 2014, 08:18

Why is this multiphase? Is the inlet Nitrogen a liquid at 80 bar?

sunilpatil · April 15, 2014, 11:23

No sir, at inlet nitrogen is in vapor state only due to sudden expansion it changes its phase

sunilpatil · April 15, 2014, 11:25

Thanks for providing material i will look into it

ghorrocks · April 16, 2014, 07:04

Have you seen the equilibrium phase change model? Look it up in the documentation.

Opaque · April 17, 2014, 00:39

ANSYS CFX uses very specific terminology to differentiate between material and phase modeling. When multiple materials are used within a single phase, it is termed "multicomponent material model", and "Eulerian multiphase" when multiple Eulerian phases are used. It is very important to understand the differences before selecting a modeling approach.

You seem to be trying to model the phase change of a single material from vapor to liquid under "thermodynamic equilibrium conditions". Theoretically, this is a process through the equation of state for the given material.

ANSYS CFX provides the "Homogeneous Binary Mixture" material to model the "thermodynamic phase change" of a pure substance modeled as a "single CFX Eulerian phase". This is the appropriate material to use "Equlibrium Phase Change" Glenn suggested.

Hope the above helps..

April 14, 2014, 03:36	joule thomson effect	#1
sunilpatil Senior Member sunil Join Date: Jul 2012 Location: Bangalore Posts: 179 Rep Power: 14	Hello every one, I am trying to simulate joule thomson effect by sending nitrogen vapor at high pressure (80 bar) in pipe with sudden expansion. for this which multiphase model i have to select in CFX (please see the attached image) Thank you

April 14, 2014, 07:16		#2
JuPa Senior Member Mr CFD Join Date: Jun 2012 Location: Britain Posts: 361 Rep Power: 15	Although not directly the same as what you're doing, Dr Thomas Frank from Ansys did the Edwards test for pressurised water (80 MPa) which suddenly decompressed to atmospheric pressure causing sudden flashing. Have a look at his papers to gauge how you'll get your problem to be numerically stable. sunilpatil likes this.

April 15, 2014, 11:23	joule thomson effect	#4
sunilpatil Senior Member sunil Join Date: Jul 2012 Location: Bangalore Posts: 179 Rep Power: 14	No sir, at inlet nitrogen is in vapor state only due to sudden expansion it changes its phase

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April 14, 2014, 08:18		#3
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	Why is this multiphase? Is the inlet Nitrogen a liquid at 80 bar?

April 15, 2014, 11:25		#5
sunilpatil Senior Member sunil Join Date: Jul 2012 Location: Bangalore Posts: 179 Rep Power: 14	Thanks for providing material i will look into it

April 16, 2014, 07:04		#6
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,854 Rep Power: 144	Have you seen the equilibrium phase change model? Look it up in the documentation.

April 17, 2014, 00:39		#7
Opaque Senior Member Join Date: Jun 2009 Posts: 1,873 Rep Power: 33	ANSYS CFX uses very specific terminology to differentiate between material and phase modeling. When multiple materials are used within a single phase, it is termed "multicomponent material model", and "Eulerian multiphase" when multiple Eulerian phases are used. It is very important to understand the differences before selecting a modeling approach. You seem to be trying to model the phase change of a single material from vapor to liquid under "thermodynamic equilibrium conditions". Theoretically, this is a process through the equation of state for the given material. ANSYS CFX provides the "Homogeneous Binary Mixture" material to model the "thermodynamic phase change" of a pure substance modeled as a "single CFX Eulerian phase". This is the appropriate material to use "Equlibrium Phase Change" Glenn suggested. Hope the above helps..