Air Cooler Fin tubes - Minimum Thickness of fins

[m.wasif]

We are using CS tubes with extruded type aluminum fins for Air Coolers. Our specifications for tube are:
Tube: OD 1", 14BWG, CS
Fin: OD 2 1/4", Pitch 3.175mm, thickness at crest 0.2-0.3mm, Aluminum B221-6063-0
Some suppliers are quoting for fin thickness of 0.4mm.
May i cross reference the quoted thickness with some material / design standard or should i remain firm with design specifications?

 

[EmmanuelTop]

GPSA Databook quotes two types of fin height/fin density per meter, for 1" tubes: 12.7 mm by 354 and 15.9 mm by 394. Your device appears to be of the second type.

Dejan IVANOVIC
Process Engineer, MSChE

 

[m.wasif]

Thanks for your answer ,through this data how may i know that fin thickness of 0.4mm is acceptable or not compare to our design fin thickness of range 0.2-0.3mm??

 

[IRstuff]

How can we possibly know whether a thicker fin is acceptable to your heat exchanger design? What is the traceability of your design requirements? What does the engineer who came up with these requirements say? What does the supplier say about how much better or worse is the heat exchange?

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[EmmanuelTop]

Fin thickness 0.4mm (0.016") is standard size for many air cooler suppliers - to name a few: Hudson, Harsco/Hammco, Thermal etc. If you are asking if it is OK to have 0.4mm fin thickness, the answer is yes.

Dejan IVANOVIC
Process Engineer, MSChE

 

[IRstuff]

Looking at the fin thickness by itself is not necessarily a valid thing to do. You have a system that consists of fins and spaces. While a thicker fin means increased thermal conductivity, it also lessens the air gap between the fins, which might have a more drastic impact on the convective transfer coefficient.

While the OP's fin pitch is seemingly large, relative to the fin thickness, I don't know for certain that increasing the fin thickness won't decrease the overall heat transfer coefficient, since the added thickness is increasing the thermal conductivity of a component that potentially already has a decent thermal conductivity, while the reduced gap might noticeably drive down the convective heat transfer.

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