Plain Tubing Vs. Fin Tubing
Plain Tubing Vs. Fin Tubing
(OP)
Hello,
I am currently investigating the redesign of a heat exchange unit that uses SS helical coil for heat transfer purposes. One avenue of investigation I am reviewing is to use fin coils instead of the standard 1.25" tubing to reduce the overall length of the required coil whilst giving similar sq.ft of heat transfer area. I have had an extensive search online but cannot find anything to give a comparison between fin and non-fin pipe. Does anyone have any info on this subject or could point me in the right direction please?
I am currently investigating the redesign of a heat exchange unit that uses SS helical coil for heat transfer purposes. One avenue of investigation I am reviewing is to use fin coils instead of the standard 1.25" tubing to reduce the overall length of the required coil whilst giving similar sq.ft of heat transfer area. I have had an extensive search online but cannot find anything to give a comparison between fin and non-fin pipe. Does anyone have any info on this subject or could point me in the right direction please?





RE: Plain Tubing Vs. Fin Tubing
Start here, it's more complicated that just thinking "5 ft of finned coil = the surface area of 20 ft of plain coil so my heat transfer will be the same". How successful fins will be will depend on the fluids and the anticipated heat transfer coefficients on each side. Process air coolers for example use fins on the outside because the heat transfer you get with air is relatively poor so the additional area of the fins compensates for the low heat transfer coefficient.
Now if you had steam condensing on the outside of tubes to heat say molasses, fins on the outside likely aren't going to help you since the steam side is likely going to have a far greater heat transfer coefficient than the molasses side.
Fouling is another factor to consider. If the outside isn't a clear service, fins may not be a good idea.
RE: Plain Tubing Vs. Fin Tubing
RE: Plain Tubing Vs. Fin Tubing
It may require a pump change if fluid. Probably not a fan change if gas, but that's a possibility.
RE: Plain Tubing Vs. Fin Tubing
Thanks for the responses. To shed a bit more light the heat transfer is for hot water to cold water inside of a tank with hot water flowing through the pipe in question. I understand that it is not just a case of matching sq. footage, as the fins cannot be treated as direct heat exchange surface, but I had thought there would be some measure of conversion rate to standard pipe of the same dimensions.
As I am dealing with the same medium with decent heat transfer and also there being no issue with the added flow resistance of the fin tube I would consider the design of merit. It is more a case of how the two compare to each other in terms of performance.
Thanks
RE: Plain Tubing Vs. Fin Tubing
If you are looking to replace an existing heat exchanger with a smaller foot print, consider using a "flat-plate" heat exchanger.
RE: Plain Tubing Vs. Fin Tubing
Any chance you could elaborate further on your opinion as to why you don't see a benefit? I have been looking around and seen that fin tubes are used in water heat exchangers commercially but they dont seem to be the norm. This may be what you're eluding to in that it is not an overall cost effective method but still cant find anything definitive.
Currently reading through the suggest texts and from what I can see it would be a method of reducing the footprint. Unfortunately the plate HE wouldn't really be in line with the avenues I have been asked to explore at the moment so wouldn't really be an option.
RE: Plain Tubing Vs. Fin Tubing
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RE: Plain Tubing Vs. Fin Tubing
RE: Plain Tubing Vs. Fin Tubing
With SS coils in aerated hot water service, check with a materials selection engineer if chlorides will influence materials.
RE: Plain Tubing Vs. Fin Tubing