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Old   June 28, 2009, 05:13
Default Need help simulating heat exchanger
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Hi there,
I am currently trying to simulate a 3-D concentric tube heat exchanger and im using gambit and fluent as my simulation tool. The cold fluid is flowing through the outer tube and hot fluid through the inner tube. However the simulation result always show that no heat transfer between those two medium. I've searched online and one possible solution maybe using shadow walls, but i have no idea how to create one.

Can anyone please help me and guide me through how to create a shadow wall using gambit??
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Old   June 28, 2009, 07:45
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Quote:
Originally Posted by veronicayeo View Post
Hi there,
I am currently trying to simulate a 3-D concentric tube heat exchanger and im using gambit and fluent as my simulation tool. The cold fluid is flowing through the outer tube and hot fluid through the inner tube. However the simulation result always show that no heat transfer between those two medium. I've searched online and one possible solution maybe using shadow walls, but i have no idea how to create one.

Can anyone please help me and guide me through how to create a shadow wall using gambit??
1- Is it possible to attache your mesh to the post
2- can you describe your BC
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Old   June 28, 2009, 09:20
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Hi, thx for replying.... I'm trying out first with a basic concentric tube. It's like a countercurrent heat exchanger. So, i'll have inlet and outlet flow. And the inner and outer walls. But, problem is i dunno how to let the heat transfer from the inner tube to the outer tube.

I've uploaded the mesh file to the following link, see if it's ok:
http://www.mediafire.com/?bv3w5wwmwzm


Thanks.
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Old   June 29, 2009, 03:25
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Quote:
Originally Posted by veronicayeo View Post
Hi, thx for replying.... I'm trying out first with a basic concentric tube. It's like a countercurrent heat exchanger. So, i'll have inlet and outlet flow. And the inner and outer walls. But, problem is i dunno how to let the heat transfer from the inner tube to the outer tube.

I've uploaded the mesh file to the following link, see if it's ok:
http://www.mediafire.com/?bv3w5wwmwzm


Thanks.
I do not know what to do with the file you uploaded, sorry for that fellow (can not download it or see its content, needed an image of the mesh not the mesh file which you seem to have uploaded).
I just wanted to check the mesh quality and how it is structured.
Look, what I gather from your description, I guess your mesh is not internally connected, that is to say, you have two regions that are not connected. go back to Gambit, join the different regions and form one mesh then export it. Good luck
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Old   June 29, 2009, 08:09
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do you have the energy equation turned on?
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Old   June 29, 2009, 09:46
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yes, i've turned the energy equation on. Sorry ahmed, im not sure wat u meant by joining both regions together. Could u pls advise? btw, i've uploaded the image of my mesh file.
Attached Images
File Type: jpg grid.jpg (91.0 KB, 29 views)
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Old   June 29, 2009, 11:43
Default That is exactly what I wanted
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Quote:
Originally Posted by veronicayeo View Post
yes, i've turned the energy equation on. Sorry ahmed, im not sure wat u meant by joining both regions together. Could u pls advise? btw, i've uploaded the image of my mesh file.
That is much better, now you have read your case in Fluent, so do this
Display ---> Grid
a pop up panel will show up, in the Surfaces list, how many surfaces with wall label you have, and where they are located (you can select and deselect the surfaces you want to display), do you have a wall between the Red colored region and the blue one?
If so, go back to Gambit
Good Luck
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Old   June 30, 2009, 09:02
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thx for the advice... i'll try to eliminate the extra wall and see if it works. Thx a lot =)
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