6 replies to this topic

[Sanjayr126]

1. What should be the L/D ratio assumption in Heat Exchanger Design/Rating in HTRI for below systems ?

     a. Liquid-Liquid

     b. Gas-Liquid

     c. Gas-Gas

 

2. How to reduce the overdesign in HTRI?

[Pilesar]

There is no standard L/D ratio assumption in Heat Exchanger Design/Rating in HTRI. Tubes come in standard sizes, so choose one that seems reasonable and then optimize the design. Reducing surface area is one way to reduce heat exchanger overdesign. 

[breizh]

Hi,

Consider these documents support your work .

To me nothing is related to software , only good engineering practices .

Good luck

Breizh 

[lnbsak]

I you have access to Aspen EDR. It can provide you an estimate of optimized STHE based on a few factors. But you can surly design based on Engineering judgment, vendor communications etc.

[Prim]

In thermal design, the L/D ratio (Tube Length ÷ Shell ID) isn’t just a number—it’s the sweet spot between performance, cost, and practicality.

???? Too Low (L/D < 3): Oversized shell, poor heat transfer efficiency, higher material cost.
???? Too High (L/D > 12–15): Vibration risks, high pressure drop, fabrication & transport difficulties.
???? Optimum (L/D ~ 6–10): Balanced heat transfer, manageable pressure drop, cost-effective design.

[deft clay]

In thermal design, the L/D ratio (Tube Length ÷ Shell ID) isn’t just a number—it’s the sweet spot between performance, cost, and practicality.

???? Too Low (L/D < 3): Oversized shell, poor heat transfer efficiency, higher material cost.
???? Too High (L/D > 12–15): Vibration risks, high pressure drop, fabrication & transport difficulties.
???? Optimum (L/D ~ 6–10): Balanced heat transfer, manageable pressure drop, cost-effective design.

 

Is this an AI response?

 

 

When I am starting a new S&T exchanger in HTRI, I use 12:1 as a starting ratio to get the design going. That is, 1 foot of length for 1 inch of diameter.

 

A few points:

• The easiest and cheapest way to add surface area is to increase the length. There is a limit to that of course.
• Higher shell lengths tend to increase undesirable bypass. 
• Extremely small shell diameters (under 8") tend to have high bypass% built-in because the tolerances don't scale down.

[breizh]

Hi,

Even this is an old thread, I share with you a document issued by Art Montemayor based on works from Dale Gulley.

Note: Every chemical engineer should have a copy of: Process heat transfer by D.Q Kern. 1rst edition.

 

Additional documents added.

 

Breizh

Attached Files

•  process_heat_transfer_hof_master.xlsx   2.51MB   18 downloads
•  Shell Pressure Drop.pdf   6.64MB   25 downloads
•  John H. Lienhard IV, John H. Lienhard V - A Heat Transfer Textbook, Solutions Manual-Phlogiston Press (2020).pdf   12.57MB   14 downloads
•  heat_exch_design.pdf   1.18MB   23 downloads
•  EXXON MOBIL - Heat Transfer & Heat Exchangers.pdf   812.53KB   14 downloads
•  TEMA_Designations.xls   96.5KB   12 downloads
•  TP - heat exchanger design basis.ppt   1.55MB   10 downloads
•  Donohue_Article heat transfer and pressure drop.pdf   3.84MB   15 downloads
•  Shell & tube HX course.pdf   838.59KB   28 downloads