LMTD for CROSS-CURRENT Heat Exchanger

[Phani Y]

Hi All,

Can someone please let me know how to get dT1 and dT2 for LMTD calculation for a CROSS-CURRENT Heat Exchanger? Is it the same as that of a Counter-Current Heat Exchanger? If it is different, please explain and post any useful links for it.

 

[georgeverghese]

For cross current flow HX, to get corrected LMTD, see diagram (h), fig 11-4 on page 11-6, chapter of heat transfer equipment, in Perry Chem Engg Handbook, 7th edition.

 

[Phani Y]

George,

I don't have it with me. Can you please share the book with me? If not the entire book, at least the pages that you mentioned?

 

[IRstuff]

It's different; a counter-flow HX has pipes running parallel, but the flows are in opposite directions, while a cross-current HX has pipes running perpendicular to each other.

There are a lot of configuration choices, even for cross-flow, so you need to describe your configuration in detail --> number of shells, number of rows, number of passes.

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[georgeverghese]

You can also look up Perry 6th edition for the same. A more detailed illustration may be found in the ever popular "Process Heat Transfer " book by DQ Kern in Fig 16.17 in the chapter on Extended Surfaces.

 

[IRstuff]

Seems like Kern goes into a little more detail on the derivation than Perry

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[moideen]

the same counter flow formula is using for cross flow calculation. i attached a excel file of counter flow and co-current. and go to the link cross flow online calculator. the online cross flow calculator follow the same formula to find the LMTD of counter flow.you can check. if something i missed , you can correct me
Link

 

[Phani Y]

Guys! I need to calculate LMTD for Kettle Type Reboler (TEMA Type - BKU)... Can someone please help me?