Air side fouling resistance of Air coolers

[Sawsan311]

Dear All,

The air side fouling resistance was specified as 0.00035 W.m2/K in one of the engineering specifications. In my view, this is even almost equivalent to crude oil applications I would like to ask the basis of such specification, is this targeted to maximize the pressure drop across tube bundle as the air side pressure drop shall be at least 95% of the total pressure drop.

Thanks

Regards,

 

[pierreick]

Hi,
Attached a comparison table for air coolers, none of the vendors are considering dirt coefficient on the air side.
Make sense to me, regular cleaning of the fins is required.
Note: Brochure from Hudson

https://files.chartindustries.com/hudson/BasicsofACHEBrochure-Web.pdf

Pierre

 

[LittleInch]

This is a heat exchange ristiance, nothing to do with air resistance.

It seems to say that this allowance should be used in the overall heat transfer coefficient to allow for some level of fouling but look to me to be a very low number.

So even with 50K difference in temp this is only 0.0017 W/m2. That's nothing. Have you got the units right?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Sawsan311]

Agreed, the resistance is assigned to the tube side exposed to the air and to accommodate degree of fouling and dirt accumulation on the tube side of the air cooler. The mentioned number is confirmed with the units in m2. K / W2 and value of 0.00035 which is comparable to other process applications like gas and crude oil.

 

[pierreick]

Hi,
A link underneath with several examples, to confirm my thoughts.
By the way, the fouling coefficient seems to be for liquid inside the tubes.

https://eclass.uth.gr/modules/document/file.php/MIE_U_156/ΜΕΛΕΤΕΣ ΠΕΡΙΠΤΩΣΕΩΝ/CEP_Finned_Tube_HX.pdf

Pierre

 

[LittleInch]

You've just stated a completely different set of units...

"W.m2/K " in the OP, now "m2. K / W2"

What is it ?



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Sawsan311]

Sorry there was a typo error, the unit of the fouling resistance is 1/U = m2.K/W

 

[LittleInch]

I agree with pierre and your OP - this is more like the internal fouling factor - see

https://www.engineeringpage.com/technology/thermal/fouling_factors.html

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.