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-   -   Heat Transfer in a pipe flow(hot air) (http://www.cfd-online.com/Forums/main/83972-heat-transfer-pipe-flow-hot-air.html)

Saima January 17, 2011 08:08

Heat Transfer in a pipe flow(hot air)
 
Hello,

I am working on a pipe flow(hot air, compressible)for which i have boundary conditions:
Pin = 533 Kpa
Tin = 700 K
mass flow rate: 0.68 kg/sec (outlet)

This pipe is insulated witha another material. I know k =0.70, and outside temperature in 343 K. , its like convection...conduction ...and then convection

Now i have to figure out wat will be the surface temperature after applying this insulation.

I did some basic calculation from heat transfer book (conduction+convection) for pipe in radia direction and found TSur = 400K.

But when i tried this in CFX by giving the above boundary conditions plus wall with heat transfer coefficient (h = 1/R: from analytical convection+conduction), it gave me surface temperature 698K.

1. Am i applying the right boundary condition for Heat Transfer on wall?

2. Do i have to do meshing for insulation material as well?

What will be the right way to applying heat transfer boundary condition for hot air inside pipe pluse insulated wall and then natural convection?


Kindly guide me.

Regards,


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