S'charger Intercooler Cooling

[finman]

Are Supercharger Intercoolers (Water - Air) usually cooled by the engine Jacket water or a seperate closed circuit system?

It's accepted that the seperate closed circuit system would perform marginally better due to a lower coolant temp but is it worth it for all the extra plumbing and wieght etc etc.

 

[spereira]

hi again

I don't think you can use the engine jacket water as a cooling medium for the after cooler since its normal temperature is around 90ºC and there's no way you can cool down the compreesed air temperature to a temperature lower than this i.e intake temperature would always be higher than 90ºC. Water to air IC kits come with a small air-to-water radiator to further decrease the coolant temperature. I'm sure it's a separate closed circuit but I'm not sure if there's a bypass to the original engine water circuit or if it's a completely isolated circuit.
try looking for water-to-air after cooler kits in the net.I'm sure that you'll get a good idea of what is really needed for a set up like this.

Regards,

Susana

 

[finman]

Hi Susana, thanks for the input, but are you sure that the charge air is cooled to lower than 90C ? !!!!

The other point that concerns me is that the temperature difference between a Closed circuit system with a small rad and the Jacket water system is not that great compared to the 300C air temp. Is the benefit that great?

 

[spereira]

Hi Finman,

As for your first question, I’ve seen logs from TDi engines where intake air temperatures drops to 50ºC…this with an air-to air IC.
As for your second question, I’m not sure what you mean by it but with a closed system and a small rad you can bring the cooling medium to a temperature well below jacket water hence increase the driving force that determines IC efficiency.

IC efficiency is given by

Efficiency = (T compressor discharge-T cooling medium)/(T compressor discharge-T IC discharge)

Suppose a 75% efficiency and T compressor discharge of 300ºC

If you have jacket water, hence 90ºC as cooling medium, IC outelt temperature will be 142.5ºC
If you have coolant temperature down to 30ºC by the small rad, IC outlet temperature will be 97.5ºC,
the question here being able to design an IC core that can perform the job.

Hope this helps,
Regards,
Susana

 

[finman]

Hi Susana,

Thankyou for your input, it's invaluable.

The company I work for certainly believes that our intercooler is one of the best around and has the advantage that it self calibrates the charge across all cylinders (when used close coupled to the inlet stubs).

I've been in engine cooling for years but never had to deal with a water/air CAC. hence all the dumb questions!

I assume your in UK automotive business, possibly LR?

 

[spereira]

Hi Finman,

I'm not in the automotive business, though I would like to ;-)! I work in a chemical plant. Part of my job is to design process heat transfer equipment, mostly shell and tube HE, nevertheless, the same HT principles applies to charge air intercooling. Anyway, I'm interested in this because I would like to improve intercooling on my car. Does your company specialize in passenger vehicles or is it bigger engines? what do you mean by "self calibrates the charge across all cylinders"? sometihng to do with an even charge air distribution between all cylinders?
why are you thinking on using water-to-air IC? space restrictions or this application isn't for a vehicle? air-to-air IC should give you a better efficiency without all the extra plumbing!

Regards,
Susana

 

[finman]

Hi Susana,

We are a Heat Exchanger manufacturer and have a vast range of "Fin and Tube" matrices, Our production method ensures higher fin to tube joint efficiency and a lower pressure drop than normal "Bulletted" fin and tube matrices. Our products are not suitable for Air-to-air.

We currently supply into the Marine charge air, Chemical, Automotive, traction and industrial markets. We can put any material of fin onto any material of tube!

The charge to all cylinders is evenly distributed assuming that the intercooler housing is close coupled to the intake ports of each cylinder.

We have already had our product trialled by a major uk car manufacturer and it was superior to all the other competitors.

We now want to expand into small volume automotive intercooler production. I have little experience of the application and needed a reliable Tube-to-header joint but, had no idea of what temperatures I would be seeing downstream of the supercharger.

I spent ages browsing the web and there seems to be alot of people who are using water-to-air cooling although I would agree with you that air-to-air maybe more compact.

Applications are found on Mazda miata which is a fairly small and compact vehicle although our trials were done on a large sports car.

Thankyou for your input, If I can assist with you intercooling requirements drop me a line at devans@elfin.co.uk