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solid to solid radiation
Posted May 3, 2011, 6:50 a.m. EDT Heat Transfer & Phase Change Version 4.1 4 Replies
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I model a furnace. It is a tube. A part of this tube's wall is the heated area of the furnace. The temperature of inside of the tube reads 900 C, so that the heat transfer mechanism from tube's internal wall to all components inside the tube (two beams and cups) is radiation.
For this modeling, I am using Conjugate Heat Transfer module (because inside the tube there is a laminar air flow passing, and I am interested in both velocity and temperature profiles inside the furnace).
In order to include radiation heat transfer from tube's wall to tube's internal parts, should I add a surface cylinder to my geometry then say the radiation is from this surface to .... (but in this way no material I could add to this surface [to be able to count for view factor and so ...]), or I should make two solid cylinder and substract them from each other to make a shell then it is possible to add material of construction to this wall, or even none of above mentioned ways but just work with workplace ?
I attached my geometry for better understanding here.
I really appreciate any kind help.
Attachments:
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if you have a tube inside a tube and you are interested in the heat exchange by radiation between the tubes, AND the tubes are "long" compared to their diameter a radiation to ambient should do since you have a nice symmetric case and the view factors will cancel out. This is valid for a starting simulation.
If you need to go further into details, then you could consider drawing the external exchange surfaces.
Anyhow it's worht to do a little hand calculations too, to check your model
--
Good luck
Ivar
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Many thanks for your kind reply.
I think I didn't explain my case well or maybe you misunderstood.
There are no "two tubes" here !
I have only a tube which you can see in both pictures, and a part of the wall of this tube is getting hot and radiates the heat to the internal components (two beams and cups at the end of them).
Now I want to introduce this radiation from this part of tube wall to internal tube. This is while inside the tube I have laminar air flow+two beams (from Alumina)+two cups at the end of the beams (from Alumina)+a carbon sample inside one of the cups. (I attach my model to see it better). So that each of these parts (air,beams,cups, carbon) will adsorb the radiated heat from the wall according to its own view factor compare to wall material of construction.
But how to add material of the construction to wall?? This is the challenge for me!
Shall I make a solid shell? shal I make a surface cylinder? shall I not make any wall (cylinder) but work with my work place wich is the same position as the tube wall?
I attach you two works, one I made a surface cylinder, another I made a solid shell.
Attachments:
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Because when I click right "Conjugate Heat Trasfer" I can just see "Surface to ambient radiation" but no "surface to surface radiation" !!!
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Nagi Elabbasi
Veryst Engineering