Temp drop over distance in large size duct

[chunk1227]

I have never had experience in working with ducting of this size or temp and was wondering if anyone here could give me a quick and dirty number. I have a thin wall metal duct measuring 30 inches in diameter. Dry air enters the duct at 210 deg. C. The air will travel roughly 100 meters, then exit. I need to know what the temp will be at the exit. It is ok to assume stagnant 25C air around the outside of the pipe. The one variable I am guessing on is the flow rate in the pipe. I am guessing velocity is around 10ft/sec.

 

[IRstuff]

You have convection and radiation. You can do the calculations piecewise, say every 10 m. Calculate the loss for the 1st 10 m, adjust the temp, do it for the next 10 m, etc.

TTFN

FAQ731-376

 

[KernOily]

What's the pressure at the duct inlet?

 

[dvd]

10 ft/sec (600 ft/min) is pretty slow for industrial ducting. If you have to convey any dust or particles it is going to settle out and may cause cleanout issues. By not insulating the ductwork and running slow air velocity are you trying to cool the air down? There may be other ways to cool the airstream.