Equivalent Thermal Conductivity of Bi-metal Heat Exchanger Tubes

[DK44]

In a typical Shell & Tube Heat Exchanger, the tubes are of Bi-metal, having different Thickness and different Thermal Conductivity.
Tube OD = 19.05 mm
Outer Tube MOC X Thk = Incoloy 825 X 0.84 mm
Inner Tube MOC X Thk = 70/30 Cu Ni X 1.22 mm

I guess,
If resistance of composite tube = t/K,
Outer Tube resistance = t1 / K1
Inner Tube resistance = t2 / K2
Then adding the resistances serially.
t/K = (t1/K1)+ (t2/K2)

Is my approach correct or is there some other method?

 

[IRstuff]

That depends on your desired accuracy; the OD is only about 20x the layer thickness, which will affect the actual thermal resistance.

see page 4 of

https://web2.clarkson.edu/projects/...es/Conduction in the Cylindrical Geometry.pdf

for calculation that accounts for the circular geometry

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm