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Heat Transfer In Agitated Vessels With Multiple Turbines

heat transfer; agitated vessels multiple turbines heat transfer coefficient

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#1 Shashidhara

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Posted 11 August 2021 - 03:21 AM

In the article "Agitated Vessel Heat Transfer"  by K J Carpenter correlations given are for Single impellers. How does the correlation get affected for Multiple Turbines?. Most of the Bioprocesses use Three Turbine impellers. Is there any correlation available for multiple turbines?

When I use the standard correlation available in the above article I end up with a large heating time for the batch. Please advise.



#2 breizh

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Posted 11 August 2021 - 03:50 AM

Hi ,

You may find pointers in the document attached .

 

Note :

let you try to find copy of the work done by Nagata on the subject . 

In the expression of the Nusselt number there is a ratio ( HA/HL ) powered with a number between  (0.12 - 0.20 ) ;

HA is an average value for the location of the agitators = Sum (HAi )/n 

 

HAi :location of the individual impeller ,

n:number of impellers 

HL : Height of the liquid in the vessel 

*reference point being the bottom of the vessel for HAi and HL  

 

 

 

Thanks to share with us the correlation used by the author in the article mentioned .

 

Good luck 

 

Breizh 



#3 Shashidhara

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Posted 11 August 2021 - 10:38 AM

Dear Breizh,

 

Thanks for the article and suggestion regarding the height of impellers. Could you give me the title of the paper by Nagata or some more detail on the paper so that it makes my search for the paper easy?

 

Regards,

 

Shashidhara



#4 breizh

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Posted 11 August 2021 - 08:26 PM

Hi,

I have attached an extract of my notes about Agitated vessel , with the correlation I mentioned above . Underneath I will define the terms of the correlation (5-11) related to a vessel  with a jacket . Unfortunately the document is in French .

 

correlation valid for jacketed vessel with or without coil inside , with baffles, Rea >100 (Reynolds number agitator) Nagata & collaborators

 

Nul= Nusselt jacket 

T :diameter of the tank

Vis = viscosity at wall /viscosity of the mass 

D:diameter of the agitator 

qi: width of each blade , Sum qi = summation of the width of all the impellers

np :number of blades per impeller 

teta :inclination angle of the blade

HA = average location of the impeller = Sum (HAi) /number of impellers 

HL = height of the liquid 

 

Good luck

Breizh 

 






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