Painting Intercooler?
 

Anyone had ever spray painted their intercooler Black? Is it possible to coat the intercooler with some sort of high temperature spray paints?

I don't have data to back this up so it may be far fetched. I think that painting the IC would decrease efficiency because the aluminum would not be able to conduct heat transfer as well. Not that the paint would hold heat in(which it might) but the air would not "cool" as much as it passes through the IC fins.
Get a bar and plate IC they look awesome, if you don't like the way it looks you could put some sort of grill in front of it like a honeycomb or something similar that you could paint to color. I'm all about open flow though and would rather not have anything in the way of my IC.

Whenever you change the thickness of the material, heat transfer goes down. Also, paint does not have a very ideal heat transfer coefficient. I would never do it. Just keep it bare aluminum, and enjoy the wonders of modern engineering.

Well .. I know alot of people actually powdercoat theirs black.. more for a sleeper look. As a matter of fact alot of intercoolers came from the factory black. I believe the RX7 one did? As with the post above.. no proof numbers here sorry :(

buick national,supra mk3 mk4,dont those saab or volvos come black.

I have a black rx-7 and I have had no problems with it. It really adds to the sleeper effect!

but aluminum has an oxide layer anyway. oxide = bad heat transfer.

just get some radiator paint from eastwood and do it.

yup radiatior paint. still i love the the look of an intercooler, i'm not trying to hide it

I love getting stomped. I personally like the IC alum glow from the front. I'd spend my money on alumashine and make her even more radiant if I was gonna do anything.
I've never seen radiator paint, if it's good enough for a radiator then i see no reason why it wouldn't be ok. Then again i've also never seen an IC any other color. Make sure you take pics, I might change my mind.

Increasing area increases heat transfer, thats why insulation on pipes sometimes makes things worse (greater surface area). The heat transfer coeffcient would be greatest with aluminum (i would think)

I wouldnt recommend doing it, unless you can find the heat transfer coeffcient. If you want get a sample piece of alumnium paint it and we can do some tests and figure out if it would be detrimental to the performance.

You sure oxide has a worse coeffcient than regular aluminum?

Seriously, does it matter if efficency suffers a little? Will the end result actually make a difference how much power the car can make?

If someone really wants to know, dyno the car before the paint and then immediately after the paint dries. I'm willing to bet that there will be no difference beyond the typically % of error on the dyno.

Paint it pink!

What I would be concerned about would be the flow through the intercooler mainly. Convective heat transfer is what that heat exchanger does.

thermal conductivities in W/m-K:

Aluminum: 250
Aluminum Oxide: 30
Stainless Steel: 16

BUT! thin is in. since it's thin it doesn't take much to overcome its low thermal conductivity. same with paint. or plastic. or whatever...

fun science experiment time:
get an ice cube
touch it for 2 seconds (one thousand one, one thousand two, brr!)
then put saran wrap around it and touch it again. Does it feel just as cold? The plastic wrap has a heat xfer coeff of about 0.30-0.50 or so, but it's pretty damn thin... so it doesn't stop the heat flow into the ice.

wow, but still better than stainless. Where did you get those values? My heat transfer book doesn't have those (I think)

I sprayed a very light misting of Krylon flat black over the I/C, the end caps and the mounting hardware to take away from the shine and make it more stealth. I really don't think it hurt more than a layer of road dust.

I did not, however, remove the overspray on one side of the mouth which is the subject of constant harrassment.

I'll be doing a very light mist of flat black on my saab, just because I don't want to "show off" a 9" wide FMIC, lol.

i just googled and ended up at engineeringtoolbox.com

Even if you paint it, its not like the paint is going to permiate the entire thickness of the core. Spray a thin coat of radiator paint at an angle so you don't get any drips down inside the fins, and the effect should be near zero.

Although to be honest, as low as the miata air intake area is, and shrouded by the bumper, I think its kind of rare for anyone to notice whats inside.

The thing about spray paint and most paints is that it acts as an insulator. Factory intercoolers are usually powder coated, which does very little to the heat transfer coefficient because it actually bonds with the metal. The government did a lot of research for these kinds of things for the reactor plants that are in the submarines. I can't give out any more specifics for the tests, but painting is definately worse. A very light powder coat is very acceptable for the standards, and that is why everything is "supposed" to be powdercoated on the sub.

yeah, i mentioned that above... it's just thin so it doesn't really matter. even aluminum can be an insulator if its thick enough.

That is the key though, thin layer. I would not do anymore than one layer if I was going to do it. When it is layered on there, air pockets form which become super insulators, if you paint it, take your time and make sure you are not just layering it on there. Good luck.

FWIW, on my old turbo setup I datalogged before and after when I spray painted my intercooler. intake temps were the same.

That is what we needed, some evidence of someone that had done it, did you just put a real thin layer on there.

Not necessiarly he could have done this at -30 and it wouldnt have made a difference if he had an intercooler or not. But yes i would say it settles the argument, but i still wouldnt do it.

I'm tellin you... the amount of paint/AlO2/whatever on your intercooler is so small it doesn't really matter! I'll break out the theory and equations for you.
There you go. I did forget the second layer of AlO2 on the inside but honestly it's so meaningless in terms of heat transfer because it's like 800 angstroms thick.

Painting your intercooler will reduce the effective heat transfer by roughly 0.65% in this case. Just keep the paint thin or use conductive paint. Or you could shell out for anodizing in black. That would increase the Alo2 layer to roughly 0.00003m or so which would contribute less to the degradation in thermal transfer but cost you a brazillion dollars.


Matt


Equations and data from engineering toolbox.

well that is the heat transfer coefficient (i don't have my book with me so ill take your word and link), it does not accurately represent the rate heat transfer from a material because it doesn't take into account radiation.

Man i wish it was that easy to really calculate the heat transfer coefficient, but thats assuming perfect materials.

Yeah, I just put a few really light coats on it. Just enough make the IC a little less obvious.
FWIW, I used radiator paint. Got it at a ma&pa auto parts store. Ambient temps were around 95 when I tested it.

We are also considering that these are light coats, that is all that I was saying, do not just dump the shit on there, and you will be ok. Paint becomes an excellent insulator when put in a thicker application, and the thicker the layers, the more air bubbles get trapped in there, so now you also have an extra insulation blanket around the intercooler. Of course, when you have enough air flowing across the surface, the paint becomes less and less of a factor.

I bet even knowing exactly the h and k of the materials, you'd still find it was only half a percent decrease in efficiency.

As for radiation, it's probably insignificant since the ambient temp is so close to the surface temp of the intercooler but painting it black would improve radiation heat transfer anyway. ;)

fun fact sidenote: the term "radiator" for the thing in the front of your car is a misnomer. it does most of its work through convection.


Matt

Not from what Ive read, or from the heat transfer equations theres quite a bit of lose through radiation (the greater the delta t the greater the radiation loss).

But whatever, Ive taken heat transfer and did all those god forsaken derivations, I think everyone has enough information to make thier own decisions.

talk to the AMS shop from the evo forums.. they always have designs on their IC

I feel your pain... BSME Cal Poly '98.

Anyway... if it is heavily radiation heat transfer, then you should absolutely paint the thing. emissivity of paint: .9something. of ALO2: .2something. Curiously, emissivity of skin is really high too, near blackbody. I guess that's how we can feel an object's temperature so well without touching it.

But...even without the math, I'm paintin mine for stealth and so it matches my black 01 :cool:

y8s what are you doing? Im looking for jobs and theres just so many options its overwhelming

sr design engineer here: http://www.nvisinc.com

Guess with that stuff you can see yourself coming and going at the same time.:gay:

Hey ill be in DC in feb, any good places to drink?

does howdy doody have wooden balls??

hells yes, there are plenty.


feb eh? you can buy me a bday beverage.

buy you a drink? I'm a broke college student, so unless your a blonde with big tits..... jk

no but seriously you a hot blonde?

dark blonde? and the ladies think I'm hot. how bout if I FIND you some to buy drinks for. then you can buy me one.

tough negotiater, but DEAL!

Yea I dont think that painting the intercooler would make a big difference or any difference for that matter