Natural Convection of Pipe fitted with fin

[devaxrayz]

Dear Colleague and Guru,

I would like to get some opinion for natural convection of a finned pipe.

I was trying to calculated how much temperature can be dropped by simple natural convection of a pipe which is attached with radial fins. The pipe is 16" dia and the pipe length is about 500 ft (any kind of cooler is not a choice).

I've search all my references and found in Perry about what so called "fin area efficiency". This term refer to fraction of fin area that efectively added to the bare surface for heat transfer. however, nothing about heat transfer coefficient for finned surface in a natural convection so i guess it will be roughly the same as bare pipe natural convection.

So in my thought, i have to know the additional fin area, calculate the fin area efficiency and then added the effective fin area to the bare pipe surface and then calculate the heat transfer using bare pipe natural convection model by adding additional pipe length proportionally. In other word if i have "A" area of pipe and "A" area of fin with 0.5 efficiency so the heat transfer area is 1.5 "A". So if the pipe length is "B", i should calculate the bare pipe natural convection with 1.5 "B" pipe length.

What do you think about that?

thanks before for any comments and opinion,

regards,

-RAYZ-

 

[jte]

Rayz-

One question: How do you plan to inspect this 500' length of pipe?

I recall seeing the remnants of a similar brilliant idea which had to be discarded due to not being able to get thickness readings on it. Keep it practical not only for the initial installation, but for the inspection and maintenance folks as well. Anything less is inconsiderate and will lead to the early demise of the system.

Perhaps you could achieve the heat transfer you seek through several smaller bore pipes with more surface area. Without fins they are easy to inspect. Add block valves and each pipe can be repaired or replaced on the run.

jt

 

[devaxrayz]

Jte,

I also don't like the idea for problem that will be arise, including handling and installation... However, i still curious with the heat transfer issues..

regards,

-bay-