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Air-Oil Heat Exchanger trouble

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Old   September 8, 2008, 08:37
Default Air-Oil Heat Exchanger trouble
  #1
Gabriele Ansaloni
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Hi all! I'm trying to solve a problem in which a Heat Excanger (made of aluminium) cools hot Oil using fresh forced air.

I have noticed that if i set the fluid in the air side at "Air at 25 C", CFX-Pre automatically sets "Air at 25 C" also as the oil side fluid; and if I set "Oil" in the oil side, CFX sets "Oil" also in the air one.

It seems that CFX acept only ONE fluid in the same simulation. In my opinion it's impossible that CFX does'n allow to simulate a simply Heat Exchanger, so I thing I'm doing something wrong.

I have tryed also whid bifasic fluid and mixtures, but unsuccesfully.

Does anyone have a suggestion to solve my problem?

Thank you all in advance Gabriele Ansaloni
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Old   September 8, 2008, 12:36
Default Re: Air-Oil Heat Exchanger trouble
  #2
F S
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Hi Gabriele

Yes you are doing something wrong. Go through some basic tutorials if you have access to them.

Good luck
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Old   September 8, 2008, 18:19
Default Re: Air-Oil Heat Exchanger trouble
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Glenn Horrocks
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Hi,

By default CFX only allows one fluid for a single phase simulation. To do what you are trying to do and stay as a single phase simulation you have to activate an expert parameter, I can't remember its name. You might be able to find it in the documentation or ask CFX support.

Glenn Horrocks
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Old   September 9, 2008, 01:56
Default Re: Air-Oil Heat Exchanger trouble
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sumedh
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Hi Gabriele

Yes,CFX allows only one fluid, by default, for single phase simulation. To change it, create an environment variable named CFX5_NO_CONSTANT_PHYSICS and set the variable value = T, and then restart the machine.

Sumedh

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Old   September 9, 2008, 03:42
Default Re: Air-Oil Heat Exchanger trouble
  #5
F S
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Hi

Or you can go to EDIT,click on OPTIONS, then click on CFX Pre and unclick on Enable Beta features to disable it.

BOL
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Old   September 9, 2008, 05:15
Default Re: Air-Oil Heat Exchanger trouble
  #6
Gabriele Ansaloni
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YOU ARE A GENIUS!

Thank you all!

Gabriele Ansaloni
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Old   September 9, 2008, 21:59
Default Re: Air-Oil Heat Exchanger trouble
  #7
HekLeR
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This env. var is replaced by a GUI option in 11.0. No need to restart.
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