What color should your intercooler be?

[FE 065]

I often see those shiny silver intercoolers grinning from behind the facia of lucky s/c or turbo Viper owners... The gleam brings to mind the heat something-or-other theory (dynamics?) that popped up as the lastest trick some years ago in drag racing.


Black painted engine blocks, white painted piston domes etc..


A black object lying in the sun will be hotter than an identical white object in the sun, no?


Anyway, I think it went something like so in this application: If the surrounding air is cooler than the temperature of the intercooler (which it is) the intercooler should be painted black to assist in heat transfer to the cooler air. I've read where intercoolers are really heat sinks (don't know how precisely true that is), soooo?


Likewise, if the surrounding air is hotter than say, an intake manifold, painting it white will impede heat transfer to the intake manifold.


It was all a very big subject back then.. Radiators are usually painted black aren't they?


Should intercoolers mounted behind Viper facias be painted black to extract a few extra BTUs?


Some engineers will chime in I'm sure

 

[Chuck 98 RT/10]

I always thought that paint was like insulation and therefore would not be good on something that needs to dissipate heat.

 

[HOdbleFman]

Anytime that color would come in to play would be with heat transmitted through radiation. In which case the surface with the highest emissivity constant would be the best. Black has a low emissivity constant and a high absorbtivity constant. Color doesn't affect heat transfer by convection or conduction, however the composition of the surface or coating would affect heat transfer by those modes. Everything has a constant that can be found in some book that rates the absorptivity and emissivity of the material between 0 and 1. For instance by definition a perfect blackbody has an aborptivity constant of 1 indicating that it absorbs all of the heat that it receives. In real life, even though something is black doesn't mean it's absorbing 100% of the heat it is receiving. Breaking out the ol' heat transfer book, the amount of heat emmitted from an object is

Q(heat per unit area)= (a constant named after some dude "Stefan Boltzman") * (emmissivity constant)* (Temperature of the surface)^4.

Likewise the amount of heat absorbed by a surface is
Q(heat per unit area)= (a constant named after some dude "Stefan Boltzman") * (absorptivity constant)* (Temperature of the surface)^4.

An intercooler is a "heat exchanger". I sucked at heat transfer in college so don't take my word for it, but I'd say an intercooler made from a high thermally conductive material with thin sidewalls and a polished or highly emissive outside surface would be the best. Oh and the more surface area that the air is exposed to while passing through the intercooler the better for cooling purposes, yet you don't want to restrict the flow of the intake air through the intercooler. I would guess the design of the intercooler would have substantially more impact on the performance of the intercooler than the color of it.

Hey guess who doesn't have a life.

 

[FE 065]

I'm sure the design would have the biggest effect.


Doing a simple search I saw a lot of references to painting a radiator with a light coat of black wrinkle paint to increase heat radiation. That could just be wishful thinking..


There are varied theories: "black surfaces have a higher radiation coefficient (alfa I believe) then shiny/reflective surfaces. the perfect "black" radiation body has a coefficient of 1 (it will absord 100% of energy radiated onto it), while a polished (mirrorlike) metal surface can have alfa of 0,1. black surfaces absorb heat (transfered as radiation energy) faster .."



I also found something that suggested black anodizing could increase emmissivity. "Anodizing is a process to create a aluminum oxide layer on the surface to help prevent degredation of the surface, at the same time you can add dye to color the aluminum (black, red, blue, etc...). Making the surface a black anodize will help the radiative properties by increasing the emissivity of the surface. Higher emissivity means greater heat will transfer off of the surface."


Since there probably aren't alot of choices for intercoolers made to fit in the front of a Viper, increasing heat transfer through anodizing or painting might be of interest to someone with an intercooler looking to lower intake temperatures.


There really was a lot of performance magazine discussion on it like 20yrs ago..backed by scientific explanation.