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Is This Heat Transfer Coefficient Value Feasible?


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#1 Jackwill

Jackwill

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Posted 22 March 2016 - 02:12 PM

Hello,

 

I am using saturated steam at 6 bar on the shell side. This then condenses to water with no temperature change. Type of condensation is upon horizontal tube bundles.

 

Shell and tube heat exchanger is used.

1-2 pass.

Length of tubes is 4ft.

Outside diameter of the tubes is 16mm.

Flow rate of the steam is 0.133 kg/s

Velocity of steam is 1.5 m/s

Conductivity of steam is ~0.7 W/m.C

Number of tubes is 60

Estimated area from UAdT is 3.6 m

Fluid in the tubes is being heated from 90 to 100 degrees C.

 

Heat transfer coefficient I am getting is ~13500 W/m2.K

 

I understand this may not be all of the information required to calculate the heat transfer coefficient on the shell side but on face value, does 13500 seem right? 

 

I personally think its way too high, was expecting ~6000-7000



#2 srfish

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Posted 22 March 2016 - 02:52 PM

13500 is certainly possible. Years ago when thermal design was done with hand calculations, the shell heat transfer coefficient  was assumed a value of 11360 Wm2-K. or 2000. Btu/hr-ft-F.


Edited by srfish, 22 March 2016 - 02:52 PM.


#3 Padmakar Katre

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Posted 13 April 2016 - 02:37 AM

Hello,

 

I am using saturated steam at 6 bar on the shell side. This then condenses to water with no temperature change. Type of condensation is upon horizontal tube bundles.

 

Shell and tube heat exchanger is used.

1-2 pass.

Length of tubes is 4ft.

Outside diameter of the tubes is 16mm.

Flow rate of the steam is 0.133 kg/s

Velocity of steam is 1.5 m/s

Conductivity of steam is ~0.7 W/m.C

Number of tubes is 60

Estimated area from UAdT is 3.6 m

Fluid in the tubes is being heated from 90 to 100 degrees C.

 

Heat transfer coefficient I am getting is ~13500 W/m2.K

 

I understand this may not be all of the information required to calculate the heat transfer coefficient on the shell side but on face value, does 13500 seem right? 

 

I personally think its way too high, was expecting ~6000-7000

Hi,

In the example there is no sensible heat change i.e. desuperheating or subcooling hence no sensible film coeff which is typically no so high. There is only condensing coeff which typically remains in the same order of magnitude as you have estimated.



#4 Mahdi1980

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Posted 16 April 2016 - 07:00 AM

Jackwill

 

Hi,

 

Here is a useful link:

http://www.hcheattra...efficients.html

 

Heat transfer coefficient for condensing steam could be between 1000 and 3000 Btu/h.ft2.F (5700 ~17000 w/m2.k)

 

Mahdi






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