Heat Transfer

[mcglade]

Hi,

I have a material that sits at 100 degrees for 1 minute. The material is aluminium and has an area of 7600mm². I need to work out how high off the surface it would be suspended over so that the surface would not reach over 40 degrees. The surface is the same area as the aluminium and is made of wood. The room temp is 20 degrees.

This is way to advanced for my knowledge of thermodynamics. Is this possible to work out?

Can anyone help?

Thanks

 

[Tunalover]

So your initial condition is that you have a sheet of aluminum, preheated in 100 degree air for one minute then suspended over a wood surface initially at 25 degrees having the same dimensions? You want to know how high to suspend the aluminum sheet so that the wood surface does not exceed 40 degrees? How thick is the wood?

This sounds like a combination radiation/natural convection problem. What are the finishes on the surfaces, or, in other words, what are the IR emittances of the wood and aluminum surfaces? You know a picture is worth a thousand words. What are the rest of the boundary conditions?



Tunalover

 

[IRstuff]

How thick is the aluminum? How does it "sit" and 100C, i.e., how is the heat transferred in?

This is a transient problem, and non-trivial. Nevertheless, if it started at 25C and is heated in 100C air, without massive forced convection, it's likely that the aluminum itself hasn't even gotten to 40C yet.

Rather than coming up with such a problem, solve the problem of how long it takes to get the aluminum up to 100C in the first place.



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Of course I can. I can do anything. I can do absolutely anything. I'm an expert!

 

[chicopee]

I don't know about the above responders but as far as I am concerned the OP is badly written. I've read the OP half a dozen time and I still have a hard time discerning what's doing what between the wood and the Al. A sketch would be helpful.

 

[racookpe1978]

Well, a poorly written problem is typical of homework problems. No basis in reality. No data and no geometry.

No supports. No environment factors (air flow, speed, support system, plate thickness, etc.)

 

[Tunalover]

Agreed. This sounds like a college heat transfer problem that has no place in this forum.


Tunalover