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Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 1:27 PM

Dear All

I want to ask why only circular tube is used for heat transfer in boilers or heat exchangers. Why not other sections like rectangular or square sections?

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#1

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 1:52 PM

strength with no stress points....

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#2

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 2:10 PM

Round tube is easier to work with...

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#4
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Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 2:16 PM

who wants to broach a square hole in a boiler plate?....

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#6
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Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 5:31 PM

There is a device called a Rouleaux bit that can drill a nearly square hole (small corner radius). I don't know if it has ever been used for metal drilling.

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#10
In reply to #6

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 7:01 PM

I use a rotary broach... they can do squares, hexes,... any type of geometry.

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#11
In reply to #6

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 7:12 PM

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#12
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Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 7:43 PM

Waterjet will be less heat.

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#5
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Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 2:19 PM

And easier to clean too!

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#3

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 2:14 PM

Clue, get the ratio of perimeter and cross section of each geometry. Start from there and come back for a follow up question. Or may be the product of both perimeter and cross section.

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#7

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 5:41 PM

Flat surfaces offer weak resistance to pressure differentials.

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#8

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 6:12 PM

Why are you certain only circular cross sections are used?

Some heat exchangers use twisted tunes with noncircular cross section. Some use oval cross section tubing, some use floval, others use shapes for which I know of no common name,

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#9

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 7:00 PM

Whilst circular tubes have the lowest surface area/volume ratio for a linear heat-transfer device, this disadvantage is offset by ease-of-fabrication and minimum use of material. Other shapes (as mentioned) are used to increase this ratio for improved efficiency but at the cost of increased complexity and structural weakness. TANSTAAFL.

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#13

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/13/2017 10:25 PM

Cost will be a big one.

Little loss of area with a hex geometry.

And as others have mentioned, strength, easier to make, easier to keep clean.

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#14

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/14/2017 6:45 AM

hi

the flow in circular tube is more stable and steady state, less pressure drop and better heat transfer rate beside fabrication of circular tube is less cost in fabrication

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#15
In reply to #14

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/14/2017 6:55 AM

sounds like laminar flow,... if your product is shear sensitive,... maybe,... but to get an efficient thermal exchange you need a turbulent flow.

Without getting into viscosity which plays a big part in determining Reynolds Number or boundary layers.

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#16
In reply to #14

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/14/2017 7:22 AM

How pressure drop will be less and heat transfer will better compared to square and rectangular profiles.

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#17

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/14/2017 12:04 PM

Dear Mr.pradeep4u,

For a given pressure, the circular shape, gives material required is less, than the square or rectangle. This is mainly due to the hoop stress in circular shape.

In rectangle or square - eddys will be formed at the corners where as it will not in the circular tube.

However, other shapes also used.

DHAYANNADHAN.S

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#18

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/14/2017 12:25 PM

Fluid dynamics.

Its the difference between laminar flow and turbulent flow.

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#19

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/15/2017 3:57 PM

Because Robert Stephenson used them in "Rocket" in 1829, and nearly everybody has been doing so ever since.

Think about the resistance to crushing of a circular cross-section tube. Now do the same with a rectangular cross-section one.

See?

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#20

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/16/2017 6:23 AM

Consider the possibility of flat plate heat exchangers, and scraped-surface heat exchangers.

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#21

Re: Circular Tube For Heat Transfer In Boiler Or Other Heat Exchangers

04/16/2017 3:43 PM

Consider the possibility of a nonfinite quality of possibility and the implications there of.

Perhaps then it might be more productive to consider the probabilities.

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Andrew Westman (2); Brave Sir Robin (1); dhayanandhan (1); gutmonarch (1); monam (1); phoenix911 (5); pradeep4u (1); PWSlack (2); ronc (1); SolarEagle (1); Stuart21 (1); Tornado (2); truth is not a compromise (2)

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