I am working on a line which is running at temperature 500 degree C. I want to calculate the temperature at the bottom of shoe. I have done some calculation but I am not sure about the value used for h (free convective heat transfer coefficient). Is someone here can guide me of any proven way to find out accurate value of h?

Read this:

http://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=42504&Searchpage=1&Main=9325&Words=%2Btemperature+%2Bkellog&Search=true#Post42504

Hi danb

I checked the link and it is very useful for designing trunnion support.
My concern is , my line is resting on concrete and according to my company standard the temperature at the bottom of shoe should not exceed 120 degree C. So I need exact temperature at the bottom of my support. for that calculation I need to find out exact value of h so that I can calculate the temperature at bottom..
According to MSS SP-58, a temperature drop of 100deg F/in can be used for strength calculations and material requirement. So could we used this to justify client that by using his method the temperature at bottom is accurately calculated?

I do not think is very accurate. In addition, this temperature drop is only for uninsulated part I guess, so even if you use the MSS SP-58 indication, you will end up with an very big shoe. Maybe is better to use preinsulated pipe supports.

Hi danb...

Thanks for your help.. In this particular line I can go with preinsulated pipe support. but I have a lot more lines which are running at temperature lower than this line.. So I need to calculate exact temperature at bootom of support so as to find out the need of preinsulated support or bigger support..

Hi Rajeev,

For 500 C 8" pipe with 50mm CS insulation, the support temperature is around 246 C. I've used 2D heat transfer software and here is a snapshot. You may provide more information for more accurate temperature. There are many heat transfer tools and software, just use them.

Hi Farhad, Could you please provide me the exact theory behind this (equations to be used) for calculating this temperature drop?

Rajeev,
Here are 2 attachments for conduction and convection heat transfer equations.

Thanks for your help Farhad!!!!!!

Rajeev,
Here is more accurate and detailed model.