Heat dissipation

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SWR
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Heat dissipation

Post by SWR »

Just curious if anyone knows what the optimum airflow speed is for air to aid in heat dissipation through an intercooler or radiator..?
-Bjørn

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Post by John Wallace »

This may be interesting?

Radiator Cooling Design
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Post by Warpspeed »

Air speed is less relevant than getting the highest mass, or volume of air through the core. It is the moving air that carries away the heat, so the more air movement there is, the higher the heat transfer rate into the outside air.

Getting more air through the core is the trick. The best way to do that is to measure the air pressure drop directly across the core from front to rear. Anything that increases this pressure difference indicates there is more flow through the core.

Easiest way to measure this low pressure is with a differential magnehelic air pressure gauge. These gauges are not expensive, check out e-bay, they come up very frequently. Something that measures a very few inches of water would be about right. What you actually have, and road speed makes a big difference, so it is difficult to be specific about the pressure to initially expect.

http://www.dwyer-inst.co.uk/htdocs/PDFF ... 00_cat.pdf

Start out by sealing the intercooler so air cannot flow around it, instead of through it. If you still need more air, try to lower the pressure behind the cooler by fitting a front air dam, side skirts, or whatever.

Some intercooler installations can be pretty inefficient, and very little work can often make a very worthwhile improvement.
Cheers, Tony.
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Post by Bubstr »

I agree that the separation of intake and engine bay is usually the hero or zero on cooling. On circle track applications, the newer style nose pieces have smaller intake openings than the older ones, but better air dam and flares at the front of wheel opening, creating low pressure in the engine bay. All you have to do is keep them separate except for the radiator opening.
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Post by Greezer »

Have a nice day
Last edited by Greezer on Mon Jun 29, 2009 1:39 am, edited 1 time in total.
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Post by SWR »

Greezer wrote:Would there be a diference between an air to air and water to air, if that's the correct terminology?
I hear people say that since the heat transfer isn't a 100% efficient deal,you get maybe 80% of the heat going into the water,and you then have the same problem getting the heat out of the water again,which lessens the efficiency of water-air setups unless you run ice to cool it more (it will heat up,negating heat transfer)..and when the ice is gone,you have less efficiency than an air-air intercooler,since the efficiency percentages for each heat transfer "add up" to a net lower efficiency.

Where I fail to see that logic is if you run a radiator on the water-air's circuit sufficiently big to always stay at ambient water temps...wouldn't then the water cool the compressed air better,given that water has much faster heat transfer than air? I.e,if you stay away from having a heat rise in the water going back to the IC,why isn't it more effective with water as the conductor?
-Bjørn

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Post by Warpspeed »

You still lose because instead of air/air you have an air/water/air heat conduction path. Water based systems are heavier, more complicated, less reliable, much more prone to heat soak, and do not work as well.

Given the same space to work with, money spent, and total weight, an air to air system will out perform a water based system, unless there is some very unusual other design criteria, like maybe a rear mounted engine. Or very short term use such as drag racing using iced water.

I have tried both in several installations, and have had far more success with a large front mounted air/air intercooler.
Cheers, Tony.
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