3 replies to this topic

[nathandoog]

I would like to know how you go about calculating the temperature of air inside a duct at various locations along it, say you have a duct with 600C air flowing through it at 2430CFM and want to know the temperature of the air 10 ft down the duct. Any help that is given would be highly appreciated.

[tarafdar]

Dear Mr. Nathandoog,
You have given air flow rate and its temp.Only with this data it is impossible to calculate temp.drop along the duct .
The followig informations are missing:
1.Duct shape and size.
2.Ducting material.
3.Insulation.
4.Outside temp..

[sheiko]

I would like to know how you go about calculating the temperature of air inside a duct at various locations along it, say you have a duct with 600C air flowing through it at 2430CFM and want to know the temperature of the air 10 ft down the duct. Any help that is given would be highly appreciated.

Generally, compressible fluids cool upon hydraulic expansion (because of the drop in pressure). This is the case for air.
Besides, if you consider heat exchange between the duct and its environment (non-adiabatic flow in the duct), heat loss will additionnaly reduce the temperature of the fluid.
On the other hand, heat gain will obviously increase the fluid temperature.

You might find a complete solution to your problem in any textbook on Heat Transfer.

Edited by sheiko, 20 July 2011 - 08:03 PM.

[kkala]

Attached "pipe.xls" is a try to give a way to estimate inside air temperature along the duct. Steady state and simple case was considered, without heat exchanger or expansion. Estimate does not seem quite easy, hopefully the present helps.

Attached Files

•  pipe.xls   19.5KB   345 downloads