Painting Intercooler Black - Better heat dissipation?

[Z2TT]

Hello,

I was reading Cypher Industries website and found the FAQ/TECH area very informative.

What interests me though is this Question and answer :


Can I paint my intercooler black?

Yes. We prefer to coat an intercooler black, for improved heat dissipation. It is known that black effectively radiates heat better than a polished surface. Having a black intercooler core only increases its efficiency. The reason behind leaving an intercooler unpainted is only for aesthetics.

So is it true that if I painted my intercooler black it will be more efficient and cool the compressed air inside even more than an intercooler that is not black?

I see that the question mentions "Paint" but the answer mentions "Coat", so will painting it with black paint still work? Or does it have to be anodized?

[ed]

only way to tell is to test it

black annodising will be much better than clear annodisong

paint though, despite being black, is in itself a thermal insulator, and will also decrease the open flow area for air to pass through due to its thickness... so despite being able to radiate more heat (through being black) it may work out a neutral gain situation due to these other losses

[Z2TT]

only way to tell is to test it

black annodising will be much better than clear annodisong

paint though, despite being black, is in itself a thermal insulator, and will also decrease the open flow area for air to pass through due to its thickness... so despite being able to radiate more heat (through being black) it may work out a neutral gain situation due to these other losses

Thats what I thought too. I havent seen a black anodized aftermarket intercooler, I have only seen stock ones that are black anodized. If there is a benefit from black anodized intercoolers shouldn't all aftermarket onces be black anodized?

Also wouldn't black intercoolers be less efficient? because they cant radiate their heat as good as silver ones?

[Mos]

There was a thread on this ages ago.
Basically uncoated and unpainted is the best for conduction of heat from one material to another.
Black surface radiates heat better than polished surface at the expense of decreased heat transfer by conduction.
The compromise is the max for the sum of both, and black anodising is the best compromise in providing radiated heat transfer without impeding conduction too much. Black paint is not a good compromise, and the thicker the paint the worse it will be.

Why are all coolers not anodised? Because it's relatively expensive.
I wouldn't be betting that black factory coolers are anodised...

Mos.

[Z2TT]

Mos do you think that switching to an anodized intercooler will provide any worthwhile benefits for the cost?

[SeptemberSquall]

this has been done before

[old_mr2]

Mos do you think that switching to an anodized intercooler will provide any worthwhile benefits for the cost?

Im not MOS, but my guess is you will gain nothing here. except a painted look.

[af300e]

Since anodizing is effectively corrosion, how does it effect the fins which are very thin to begin with?

I had some spoked motorcycle rims coloured black and one of the effects of the process is that the spoke holes become smaller due to the thickness of the oxide layer vs metal. There is a significant chance that the holes will fill enough that the spoke nipples can no longer fit so, I ran a very slightly larger drill through the holes before I had the rims anodized.

Therefore, the layer formed is obviously quite thick. I wonder how many microns thickness of the metal is sacrificed in the production of this oxide layer? Enough to weaken the fins significantly?

I'd not be happy having a radiator anodized due to the very low integrity of the fins, but I suppose intercooler fins are generally stronger/thicker than those of radiators?

EDIT: Found this---> "Simple aluminium colouring method:
Oil it very ,very sparingly with any edible oil or fat(olive oil is best for aluminium according to old books) ,then heat it slowly to max.400 C temp.Instead oil you can use 20% shellac solution. Good luck!"

I wonder what colour it goes? Darkish?

Or perhaps a chemical bluing/blacking method such as that found on guns etc would work? It gives a very dark finish if required. Standard bluing requires oxides, but chemical blues may not.................

EDIT: Found this too, more research required on this product "Birchwood Casey Aluminum Black"
http://www.gunaccessories.com/Birchw...ey/Blueing.asp

[ProjectSleeper]

I did it on my car for no other reason than to hide the intercooler behind the grille.

I enquired about anodising, but the cost was stupidly high. In the end, I went for paint - etch primer and mat black - if I lost a few kW by doing it this way - I'm ok with that - I saved $300

[Mos]

Since anodizing is effectively corrosion, how does it effect the fins which are very thin to begin with?

Since your post is so "significantly" scientific can I answer with "Not much"?
Note that I never said coolers *were* anodised, just that black anodising provides the best compromise.

Mos.

[oldcorollas]

fwiw, an anodised layer, or even the thin aluminium layer, is very good at radiating heat..
i vaguely remember reading somewhere that the efficiency of the aluminium oxide at radiating heat is very efficient but i can't remember the exact efficiency....

anyway, the point is that any paint will reduce the effectiveness of the oxide at radiating heat, as you are providing another insulating layer (however small)..

anothe rpoint is.. that at these temperatures, you are not realyl radiating heat, it is being transferred by direct contact with the air molecules..
i forget if you call it conduction to gas, or convection.. one of them.. but point is that if only 100deg or so, radiated heat maybe be a small % of the lost heat, so blackbody or not makes little difference.
what makes a difference is the direct heat transfer to air from either paint of aluminium oxide....

i think uncoated is better, and no need to try to get anodised. painting the forward facing surfaces for non-visibility should not significantly affect heat transfer, but dipping the whole thing in thick paint 8or from spray can) WILL decrease transfer a tiny bit...


edit, scroll a bti down this thead
http://www.audifans.com/pipermail/s-...ly/042433.html
and the quote from this book
"The Surface Treatment And Finishing Of Aluminum And Its Alloys" by
S. Wernick, R. Pinner, and P.G. Sheasby, Fifth Edition published by ASM
International and Finishing Publications LTD

"It should be noted that anodized aluminum is an excellent radiating surface which approaches to within 80% of a 'black boy' regardless of its optical colour and there is no advantage to be derived from dyeing it black."

[SeptemberSquall]

convection, like a convection oven

[brett_celicacoupe]

it may work but you may want to ask yourself if you can achieve better gains for the same price/amount of work.

ie spend the $300 on a water spray system or get an intercooler twice as big...

more gains could be had for the same price by adding extra material to the intercooler. ie make it a larger heatsink.... new front bar with improved air flow...

[GasedT18]

I recall many years ago asking one of my physics teachers whether a black surface or reflective surface is a better radiator - that is emitter of radiation mostly in the infra red range. He said, somewhat counter to my intuition, that the reflective surface is a better radiator. I never followed the matter up to my satisfaction and I think he is (generally) wrong.

In the case of opposing inter-cooler tubular elements one could assume thermal radiation emitted from one tube being absorbed by an adjacent tube if not absorbed by the air. One wants to maximise the transfer to air. I haven't the figures on hand to determine the rate of airflow and/or distance between two emitters to ensure all radiation is absorbed by the air. If opposing IC elements were reflective, photons on the rebound would have increased chance of hitting a gas molecule. So there could be a trade-off.

Absorbtion and emission of infra red radiation does not correlate with visual colour. Some white substances emit more IR than dark ones.

If objects appear white (reflective in the visual spectrum), they are not necessarily equally reflective (and thus non-emissive) in the thermal infrared; e. g. most household radiators are painted white despite the fact that they have to be good thermal radiators. Acrylic and urethane based white paints have 93% blackbody radiation efficiency at room temperature (meaning the term "black body" does not always correspond to the visually perceived color of an object).

http://en.wikipedia.org/wiki/Thermal_radiation

This information supports some claims made for the following specialised anodising treatment and alloy:

http://www.fujikura.co.uk/speciality...hokka/faq.html

Being of practical mind I'd be inclined to set an IC up on a bench with a constant heated air stream through it (both ways i.e., a fan blowing through the IC as well) at the rates and temperatures dictated by your application and take a thermal photo. Then take another after having it anodised (or painted - I really doubt that very thin epoxy would make very much difference given the relative thickness of it to the aluminium substrate. It would no doubt need to be etched before painted).
If you take the photo's in exactly the same location - fixed tripod, same ambient temp & lights etc. The two images can be digitally subtracted to show the difference.

This would make a nice little practical experiment. If you could keep the variables constant (e.g., coolant temp in radiator) taking a thermal photo of the IC in your car before and after treatment might be illustrative.

Someone on Toymods has access to a thermal camera - I spotted some photo's somewhere/when?

Not to take the fun out of it, and there is a certain appeal to visual proof, a thermocouple on the input and output of the IC will show any efficiency gains or losses.

I wonder how much engineering goes into common ICs?
Has anyone bench tested them?

D

[PlacentaJuan]

for what its worth, i agree that there would be a minuscule amount of difference, but only while the cooler is flowing its maximum amount of air at the max expected temperature for the max amount of time ; a condition which you are not likely to see even on the track, let alone the street.

maybe something to consider if you were building a drag car for 1000m events.