12 replies to this topic

[Said Salim]

Greetings,
I am having a problem in estimating the correction factor of MTD (FT) for the attached heat exchanger configuration. The known parameters are t1, t2, T1 & T2.
Any one can guide me to the approperiate FT chart or formula?.

Attached Thumbnails

• 

[Said Salim]

Sorry for multiposting that was by mistake while clicking post topic I thought it was not posted.

[cea]

I am not sure whether you have understood significance of Ft factor and where it is to be used.

 

However, in order to calculate Ft factor, you are required to calculate LMTD & caloric temperature. Based on graph as per exchanger geometry, you can get Ft factor.

 

Forum may be able to help you, if  you describe your problem in detail & your understanding clearly about the assignment.

[breizh]

http://checalc.com/s...LMTD_Chart.html

 

A resource to support your work.

 

Breizh

[srfish]

You can find LMTD correction factor charts  for unusual shell types in the following EXCEL spreadsheet:

Process Heat Transfer by Art Montemayor. IT is downloadable and is It s located in the file library.on this website.

[breizh]

Hi Said ,

As per Srfish'advice , consider the great resource attached .

 

 

 

Breizh

[Said Salim]

Thank you Srfish and Breizh

3 series-2 tube pass arrangement in the excel sheet is close to my configuration.

[Bobby Strain]

Maybe, maybe not. The arrangement you show suggests that the shell side is condensing vapor, and the tube side a single phase cooling media. You need to see the shell baffle detail to get the right configuration. It seems to be primarily cross flow on the shell side.

 

Bobby

[Said Salim]

Dear Bobby,
The shell side is a process gas and the tube side is Boiler feed water. Please find more details in the attached datasheet of the exchanger.

Attached Files

•  HE-Datasheet3.pdf   687.41KB   359 downloads
•  HE-Datasheet2.pdf   1.37MB   323 downloads
•  HE-Datasheet1.pdf   1.45MB   369 downloads

[srfish]

HE-Datasheet1.pdf shows that they are TEMA type DXU heat exchangers. The X indicates cross-flow heat exchangers. You can find LMTD correction factor charts for cross-flow in the Heat Exchanger Design Handbook.

[cea]

Many thanks to srfish for taking my attention towards points mentioned in his post. Hence, I have removed my earlier post.

 

As a academic curiosity, I run HTRI for given datasheet & noted below.

No. of exchanger in series : 3

Exchanger No.  : Hot Inlet, ºC: Hot Outlet, ºC : Cold Inlet, ºC : Cold Outlet, ºC

1                        : 340ºC         : 280.8ºC           : 257.2ºC         : 310ºC

2                        : 280.8ºC      : 235.4ºC           : 216.6ºC         : 257.5ºC

3                        : 235.4ºC      : 200ºC              : 185ºC            : 216.6ºC

 

I guess, in absence of above data, Said Salim was experiencing problem of estimating Ft factor. Please correct me if I am wrong.

 

However, concern still remains is how to estimate these terminal temperatures for DXU type configuration, without help of HTRI.

[Said Salim]

Cea you are right I have a problem estimating Ft factor.Anybody can suggest how evaluate the performance of this exchanger?

[cea]

Well. Now when you have terminal temperature with you for each exchanger in series, you may refer to applicable graphs for exchanger geometry wherein you can read Ft factor directly based on terminal temperature. Well known source can be Kern Book.