8 replies to this topic

[Mojo142]

Hello everyone,

 

I am designing a heat exchanger for the cooling of concentrated sulfuric acid using a shell and tube exchanger, and I was wondering what are the typical overall coefficients for the cooling concentrated sulfuric acid, with water being the cold fluid. I am unable to find any mineral acid values in the books by TEMA, Ludwig, or Richardson.

 

 

Kind regards,

 

M

[Pilesar]

Unless you find a more specific reference, I would assume behavior similar to hydrocarbons. Temperature and concentration both affect viscosity which will be a big influence. For cooling liquid with no phase change and without other info, I would estimate overall heat transfer coefficient of 40 BTU/hr-ft2-F for 5 cP. I would use double that for 1 cP and use half that value for 10 cP. But you know more about your fluid conditions so don't take my word for it. For a student project, you have references and you should probably use them. Which referenced fluid is most like the fluid you have? Are their several fluids that might be similar? Is there no conservative value that would give you a reasonable design if you are incorrect about the heat transfer coefficient? Cite your references and state your reasons for your professor. Document your assumptions and perform the design.

  If you were taught a method to use fluid characteristics to calculate heat transfer coefficients, then use that. The calculation method may not available until after the initial exchanger design so there will probably be some design iteration required. That is part of the engineer's world, so allow time for it.

[Napo]

Mojo142,

 

I send related information.

 

Napo.

Attached Files

•  Sulphuric acid 1.pdf   173.14KB   95 downloads
•  Sulphuric acid 2.pdf   240.68KB   83 downloads

[Napo]

Mojo142,

A recommendation:"The use of air cooling instead of water cooling
is not just due to limited water resources. Often air cooling is much more economical than water cooling." of: USE OF AIR COOLING APPARATUS IN SULFURIC ACID by L. Ya. Zhivaikin, V. M. Shmerkovich, et. al. (November 1971, Chemical and Petroleum Engineering 7(11):1013-1015).

Napo.

[Muhammad 345]

Hello everyone,

 

I am designing a heat exchanger for the cooling of concentrated sulfuric acid using a shell and tube exchanger, and I was wondering what are the typical overall coefficients for the cooling concentrated sulfuric acid, with water being the cold fluid. I am unable to find any mineral acid values in the books by TEMA, Ludwig, or Richardson.

 

 

Kind regards,

 

M

 

Hello everyone,

 

I am designing a heat exchanger for the cooling of concentrated sulfuric acid using a shell and tube exchanger, and I was wondering what are the typical overall coefficients for the cooling concentrated sulfuric acid, with water being the cold fluid. I am unable to find any mineral acid values in the books by TEMA, Ludwig, or Richardson.

 

 

Kind regards,

 

M

hi i am facing the same issue can you please let me what is heat transfer coeffecient 

[gegio1960]

Dear Napo,

just for my fun, I tried to put the figures reported by att #1 in a simple spreadsheet.

Surprisingly, the results are different of an order of magnitude.

On the other side, the U calculated is in line with the advice of Pilesar but very different from the ones cited in att #2.

Moreover, I think the conversion factor used in att #2 (from btu/h/ft2/F to kcal/h/m2/C) is not correct: it should be 4.884 instead of 4.086).

The spreadsheet (in Italian, sorry) is attached...if someone would like to play with it, maybe some mistakes could be found :-)

Good luck!

gegio

[attachment deleted, see revised spreadsheet below]

Edited by gegio1960, 08 January 2021 - 05:12 AM.

[breizh]

Hi gegio 1960,

Thanks for sharing 

Agree with your comment about unit conversion .

Now I found  the resistance due to metal thermal conductivity very different from your calculation # 50 times higher !

based on external diameter , the heat transfer coefficient should be the following 

 

1/U dirt =1/(hi*Di/Do)  +1/(hdi*Di/Do) + e /(k *(Di+Do)/2 Do)+ 1 /hde +

1/he 

 

hi : internal convection heat transfer coefficient

he : external convection heat transfer coefficient

hdi : fouling internal heat transfer coefficient

hde : fouling external heat transfer coefficient 

e :pipe thickness (Do-Di)/2

Di :internal pipe diameter

Do :external pipe diameter

k : pipe thermal conductivity 

 

please check .

 

Thanks 

Breizh 

Edited by breizh, 07 January 2021 - 12:42 AM.

[gegio1960]

Thank you, Breizh.

Very good!.I'll see, correct and revert...

[gegio1960]

the file revised according breizh advice is attached.

the only difference is the calculation of the metal resistance.

the original equation was taken from GPSA, but it has been substituted by the one suggested by breizh.

the revised U is still in line with Pilesar figures.

good luck!

Attached Files

•  sulfuric acid cooler .xlsx   31.22KB   44 downloads