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Air to Liquid and Evaporative Cooling

Started by KJ_Lesnick, August 26, 2013, 03:45:14 PM

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KJ_Lesnick

August 26, 2013, 03:45:14 PM
These are the same right?  I was reading about british aircraft using a then new evaporative cooling system which sounds like just a air-to-liquid intercooler with the exception of the fluid vaporizing then being cooled back.
That being said, I'd like to remind everybody in a manner reminiscent of the SNL bit on Julian Assange, that no matter how I die: It was murder (even if there was a suicide note or a video of me peacefully dying in my sleep); should I be framed for a criminal offense or disappear, you know to blame.

wuzak

#1
August 26, 2013, 04:12:45 PM
Air:liquid refers to teh working fluid - air is one medium and liquid is the other.

In the case of an air:liquid intercooler, such as used by Rolls-Royce on the Merlin and Griffon, the liquid is used to cool the supercharged air, with that liquid then going through a radiator to be cooled.

As opposed toan air:air intercooler which has air as the cooling medium as well as air being cooled.

Evaporative cooling is liquid cooling where the liquid changes state (liquid to gas, ie it evaporates). The gas then has to be condensed back to a liquid and cooled so the process can continue. It requires much larger surface areas than conventional cooling.

Some racers used total loss evaporatie cooling systems. Such as the Me 209 V1.

KJ_Lesnick

#2
August 26, 2013, 04:48:24 PM
Wuzak

1.) So basically the difference between air-liquid and evaporative-cooling is that the liquid is vaporized in the evaporative cooling scheme and you need to radiate away a lot more heat? 

2.) I know air-to-air is more efficient than air-to-liquid; but is evaporative cooling better than air-to-air under all conditions?
That being said, I'd like to remind everybody in a manner reminiscent of the SNL bit on Julian Assange, that no matter how I die: It was murder (even if there was a suicide note or a video of me peacefully dying in my sleep); should I be framed for a criminal offense or disappear, you know to blame.

wuzak

#3
August 26, 2013, 05:47:56 PM
Quote from: KJ_Lesnick on August 26, 2013, 04:48:24 PM
Wuzak

1.) So basically the difference between air-liquid and evaporative-cooling is that the liquid is vaporized in the evaporative cooling scheme and you need to radiate away a lot more heat?

Yes. Heat of evaporation is usually more than the heating energy required to get up to vaporisation.

Quote from: KJ_Lesnick on August 26, 2013, 04:48:24 PM2.) I know air-to-air is more efficient than air-to-liquid; but is evaporative cooling better than air-to-air under all conditions?

I'm not sure that air to air is more efficient than liquid to air.

Liquid to air allows for a smaller radiator exposed to the air flow, but requires two heat transfers. Air to air requires that the hot air is ducted to the intercooler (ie radiator).

Evaporative cooling is not usually used for intercooling, but is for engine cooling.


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