convection cofficient

[engbassbosa]

how to calculate convection cofficient on vertical cylinder
and cone shape is there aprogram to calculate
or equation

 

[TD2K]

heat transfer equations for gain/loss from a vertical cylinder should be in any heat transfer textbook.

I don't know if I've seen one for a cone. You might have to look at the correlations for a cylinder and flat surfaces and depending on the dimensions of the cone, estimate the heat transfer coefficient. The Wolverine heat transfer book with their correlations for heat transfer from a studded tube might be another source of information.

 

[ione]

For natural convection across a thick vertical cylinder where

D/L >= 35/(Gr)^0.25 (effect of curvature negligible)

you can use the same correlation as that of a vertical plate:

Nu = {0.825 + (0.387Ra^(1/6))/[1+(0.492/Pr)^(9/16)]^(8/27)}^2

For slender cylinders you can take a look to this paper

http://deepblue.lib.umich.edu/bitstream/2027.42/22237/1/0000672.pdf

While for a cone....... I sincerely don't know.

 

[ione]

I've found the document in the attachment, but have not taken time to read it carefully. Maybe it could be of some help.

 

[engbassbosa]

i want to calculate heat loss from vertical tank diameter 20 m height = 12 m
the roof are cone shape

i will use your formal is it best for these case is there is better formals or there is a program to calculate it

 

[ione]

Google "predict storage tank heat transfer precisely xls" and you'll get a spreadsheet based on an article written by J.D. Kumana and S.P. Kothari (Chemical Engineering, March 22, 1982, P-127). I warmly suggest you to get the article in order to understand this stuff.

 

[TD2K]

Some cone roof tanks are quite shallow (small rise relative to the horizontal distance). If that's the case for you I would just approximate it as a flat surface in terms of the heat transfer coefficient but use the actual area for heat transfer.