Cooling Coil Calculations

[jfont]

Hello:
I'm trying to make a model to size AHU cooling coils. Reading an article posted in the Air Conditioning and Refrigeration Journal, I found that for 5/8in tubes, staggered pitch 1.5in, with 8 fpi and a 52.5 x 75 coil, they use an outside to inside surface atio R=18.3 and 22 sqft/row/face area. I follow the attached procedure to calculate those parameters (attached file) but I came up with different results.
I would appreciate if anybody could help me to understand the reason?
Thanks!

 

[gepman]

jfont
since you have not received any replies I will take a look at it. Please post or give a link to the original paper.

 

[jfont]

Thanks gepman for your reply. You can find the original article using this link

http://www.hvacindia.org.in/journals/2002oct/article01.html

 

[gepman]

jfont
I have not reviewed your calculations and the linked paper in detail but my first guess is that each fin has two sides (even though it is very thin) and therefore you did not consider the surface area of both sides. I will have to review the heat transfer theory of thin fins to see if this statement applies. It has been a while since I have done anything with heat transfer on extended surfaces.

 

[imok2]

jfont, I thought this might be of interest to you, free software.

http://www.colmaccoil.com/coilsoft.asp