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Shell & Tube Heat Exchanger

heat exchanger shell & tube chemical engineering

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#1 Molla Jafar Sadique

Molla Jafar Sadique

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Posted 04 November 2014 - 08:21 AM

SHELL & TUBE HEAT EXCHANGER
 
Shell and tube heat exchangers are the most widely used type of heat exchanger.


GENERAL INFORMATION
The inside of the exchanger contains many tubes and baffles, as shown in the picturebelow. These tubes and baffles help direct the two streams flowing through the exchanger.
 
shell-tube-heat-exchanger-schematic-3163 STRAIGHT TUBE SHELL & TUBE HEAT EXCHENGER 8ae2d5b90e272ae4ccecbf072a50466c87170ab4 STRAIGHT TUBE SHELL & TUBE HEAT EXCHENGER

 

shell and tube heat exchanger consists of several tubes enclosed in a shell. One fluid flows through the tubes while the other fluid is conducted through the shell. Flow through the shell and tubes can be countercurrent, cocurrent, or cross flow. In countercurrent flow, the shell fluid flows in the opposite direction of the tube fluid. In cocurrent flow the shell fluid flows in the same direction as the tube fluid. Lastly, in cross flow the shell fluid flows perpendicular to the flow of the tube fluid. In general, countercurrent flow results in the most efficient heat transfer.
 
 
 
products_shelltube_drawing_LG.jpg U TUBE SHELL & TUBE HEAT EXCHENGER

 

The baffles serve two functions: Their strategic positioning supports the tubes, preventing vibration and sagging, and they also channel the fluid in the shell side, resulting in more efficient heat transfer.
heatexhanim.gif U TUBE SHELL & TUBE HEAT EXCHENGER
 
Static mixers are sometimes placed in the tubes of the shell and tube exchangers to help dissipate heat. Mixing of the fluids in the tube removes temperature, velocity, and material composition gradients. Static mixers also allow fluids to be cooled near their freezing temperature without plugging the tubes.
stat.jpg Static mixer
The diagram below shows the mixing that occurs as the flow in the tube encounters the static mixer. The mixer itself does not move.
kenicsmixer.jpg Static mixer
 
ADVANTAGES DISADVANTAGES
  • Can handle fluids at hightemperatures and pressures.
  • Can handle fluids of all states.
  • Easy to dismantle for cleaning or repairs.
  • Design can be adapted to meet operating conditions.
  • One unit can only be used for one duty.
  • High amounts of heat loss occur, soinsulation is required.
  • Larger space requirements and more expensive than plate and frame.
  • Over time vibrations may damage the heat exchanger. Baffle placement may be optimized to reduce vibrations and help the heat exchanger last longer.

 



#2 tung.kstnhd

tung.kstnhd

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Posted 23 November 2014 - 09:30 AM

Thank you,.

I have a question.

Can you answer it for me?

What is main reason for different between hand calculation result and HTRI calculation result?

Thank you so much!



#3 Chinmoy_ChE

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Posted 24 November 2014 - 04:01 AM

tung.kstnhd

 

HTRI calculation is done on segment by segment basis.

 

Like in hand calculation we use bulk temperature and calculate properties of fluid at this temperature. But in real situation temperature changes along the path of STHE and even in same cross section of the STHE. So HTRI calculates heat transfer coefficient rigorously means segment by segment. 

 

Hope my reply answers your query.



#4 tung.kstnhd

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Posted 25 November 2014 - 08:57 AM

Thank you so much!






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