Chemical Engineering - Heat Transfer - Discussion

35. 

Air is to be heated by condensing steam. Two heat exchangers are available (i) a shell and tube heat exchanger and (ii) a finned tube heat exchanger. Tube side heat transfer area are equal in both the cases. The recommended arrangement is

[A]. finned tube heat exchanger with air inside and steam outside.
[B]. finned tube heat exchanger with air outside and steam inside.
[C]. shell and tube heat exchanger with air inside tubes and steam on shell side.
[D]. shell and tube heat exchanger with air on shell side and steam inside tubes.

Answer: Option B

Explanation:

No answer description available for this question.

Saurabh said: (Dec 21, 2014)  
Why finned tube? Why not shell and tube heat exchange? Please explain the difference.

Bajwa said: (Dec 26, 2014)  
A finned tube heat ex-changer usually gives 5 to 8 time more heat transfer as compare to other types, we will use air outside the tube bundles and stream inside the tubes because air may also contains some some impurities (solid particles) and it can damaged the tubes in form of clogging, fouling etc.

Faraz Ahmed said: (Dec 5, 2015)  
Fins may also be fouled, and it is rather difficult to clean fins than tubes, so why we can't prefer flow of air inside the tube ?

Saiyam Patel said: (Jul 16, 2016)  
Air may also contains some some impurities (solid particles) and it can damaged shell in form of clogging, fouling etc so it costly to replace hole shell. So I think that air is pass through tube side.

Shriman Dave said: (Sep 20, 2017)  
But with steam in tubes, it may lead to hammering as well as fouling, also with steam in shell, we could get better htc so why steam in tubes?

Sukhdeep said: (Jan 11, 2018)  
Heat exchanger here is plate type heat exchanger and no case of clogging.

Parth said: (Aug 10, 2018)  
@Shriman Dave.

The temp of the steam is greater than air and generally which has greater temp is taken into the tube side because it can cause to harm the costly shell.

Fareed Khan said: (Jan 9, 2019)  
If steam is passing through shell it will cause heat loss from shell to atmosphere. That's is loss in industry.

So always try to pass high temp fluids through the tube and low temperature outside the tube.

Trushal said: (Jan 17, 2020)  
For gas-liquid system, always fin-type H E is used.

Kiran said: (May 9, 2020)  
Steam can cause corrosion. That's why steam is in tubes.

The heat transfer coefficient of air is low. That is air is taken in shell side with finned. Fins will increase the heat transfer rate.

Yadav said: (May 11, 2020)  
@All.

The heat transfer coefficient of air is low. That is air is taken in shell side with finned. Fins will increase the heat transfer rate.

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