RKD in OKC

Careful, that is exactly what LR did with their intercoolers and no-one believes their numbers.

Motohead

I haven't posted here much, but this thread caught my attention since I am currently taking Heat and Mass transfer here at Oregon State.

First off, black is the worst color to paint anything when heat is concerned. Black absorbs the most radiation energy of any color, and a matte finish is much worse on top of that. If the intercooler is in direct line of anything warmer than it (i.e engine, exhaust, turbo or the sun) it is going to receive radiation thermal energy.

Second, any coating that I know of is going to increase the resistance for the heat to conduct out of the aluminum into the outside air. The coating may somehow increase the convective cooling on the outside of the intercooler due to air flow, but is that increase going to overcome the added resistance to conduction? Without knowing the properties, I don't know for sure.

Either way, try a test. Chances are it will be very hard to be accurate enough to get a real answer, but it would be fun to try nonetheless.

Blackwater

What happens from this post forward is going to be fun to watch.

Laust Pedersen

Yeah that search thing can be difficult and who wants to read old stuff anyway which could contradict carefully acquired opinions ... thinking of it though, thermodynamics and fluid mechanics hasn’t changes much in the past half century, so anybody wanting to dig deeper on the theory has to read “old stuff”.

Meanwhile:

Ben Z.

I was just going from the title of the post "exothermic ceramic coatings". Also, I mostly kept my nose out of the heat transfer stuff since I don't know a lot about it. Just wanted to point out the potential limitations of laser thermometers.

billthe3

Touche. Didn't even notice that.

FSAEracer03

Hahaha... you guys are silly. Instead of bench testing the intercoolers, or claiming to have omniscient knowledge on the given subject, why not try the only real way of testing them. Install thermocouples onto a car before and after the intercooler, make a set of standardized runs, and log delta t's with both intercoolers. I'm pretty sure people would take said empirical evidence as true knowledge of gains or losses.

2bridges

Apparently we think alike -
guessing you missed my post stating exactly the same

FSAEracer03

Sure did

Laust Pedersen

A bench test will answer the question whether or not the coating increases the IC efficiency and it certainly is easier than installing and removing the IC’s as well as making sure that the “standardized runs” are adhered to each time while recording the temperatures.
If the coating does improve the IC efficiency during a bench test, then comes the more difficult question of “is the coating effort worthwhile”.

Getting results from “standardized runs” still does not fully answer how it performs during daily driving, which obviously is different from person to person.

FSAEracer03, Instead of laughing about other's efforts followed by loose suggestions, how about posting a constructive suggesting for a “standardized run” that is easy to perform (and repeat) while reading the temperatures?

Laust

ausgeflippt951

That's actually not true. The reason diamond works well is because of its crystal structure. The complex "diamond crystal structure" allows for a very high thermal conductivity due to the heat capacity (assuming relatively constant temperature -- around the Dulong-Petit Limit) and phonon-phonon and phonon-electron interactions.

Honestly, I'd use any carbon material to coat an intercooler; graphite is cheapest and still possesses a very high thermal conductivity. Also, color would not matter a whole heck of a lot, because it only comes into play when there is light radiation; in the dark of your engine bay a black intercooler would not be any different than a white one.

And no, when trying to dissipate heat, a ceramic insulator would not be the most ideal. However, when trying to contain heat (as in the engine itself), ceramic would be ideal. Efficiency increases greatly as heat loss decreases.

FSAEracer03

Laust... there's an easy way, and there's a correct way. The testing methods proposed thus far (excepting 2bridges, sorry - didn't mean to steal your glory ) all lack real-world application as they all take the intercooler out of its working environment. Further, the examples of "heat dissipating" coatings mentioned are misnomers, as they are not applied on forced-convection systems.

The example for the intake and rotors is not of a heat-dissipating coating, but a ceramic coating. The insulating property of ceramics allows the surface temperatures to change at different rates than the core temperatures, and stabilize the temperatures between high variations. As I was once told "heat doesn't crack rotors... heat change cracks rotors!" We aren't trying to coat the intercoolers to add more material, nor keep heat inside them, nor keep the core temperatures stabilized, we're trying to dissipate the most heat at a rapid rate.

Also, though your example takes only one intercooler removal, and mine takes two, yours not only removes the device from its proper operating environment, and neglects forced convection. It's not a matter of ease; it's a matter of applicable and non-applicable test data. As I'm sure Motohead can tell you, currently being in a Heat and Mass Transfer class, natural convection and forced convection are beasts of two different breeds. The calculations are far more involved for forced convection, and at the end of the day, an intercooler doesn't work on radiation and natural convection, it works on forced convection, thus a proper test must not overlook it.

Getting results from standardized runs DOES give you the answer, as it shows you on-boost performance, all other things held constant. Intercoolers aren't complicated devices. Their performance is based on their ability to shed heat.

I laughed at all of this simply because it is silly. If you want to test two intercoolers on a given setup, and a given car... then test two intercoolers on a given setup, and a given car! It isn't rocket science to make a standard test to do so. Warm the car up to operating temperature, and datalog some hard pulls. Go back home, review the delta t's, and the conclusion is drawn out for you in real-world numerics. The end.

Laust Pedersen

Ha ha, my turn for an overbearing laugh at your “know better” attitude.

Although it has been a while I do have a handful of completed high level thermodynamic and fluid mechanic courses under my belt with good grades, since I studied hard to understand and use the concepts. So I am not particularly ignorant about what is going on in and around an intercooler.

True, heat exchangers are not rocket science. They are analyzed and characterized using thermodynamics and fluid mechanics and as usual, oversimplification of a test can easily produce random and useless results.

Charactering standardized runs as “hard pulls” after warm-up is an oversimplification, which will give useless results and waste peoples time attempting to extract useful information, unless a number of precautionary measures are taken. Since you specify the test, it is your job to point to non-obvious conditions that need to be kept constant to produce repeatable and trustworthy results and let me assure you that there are a number of (obvious and non obvious) conditions, which could skew the results one way or another.
I also see that you presume that a data-logger is readily available. If it is not already installed then that certainly complicates the measurements.

You are dead wrong in assuming that the test I proposed does not give the answer to the question that this thread is based on. Read item 4 in my test specification, this will ensure that some air flows through the fins induced by a thermal gradient (hotter IC than ambient air). While the flow is maybe 2-5 mph it is enough the make convection (rather than radiation) the dominant heat transfer (cooling) mechanism and the test valid.
An IC works on convection, forced or not. Changing the external flow merely changes how many calories/sec are removed. The outcome of this experiment (to coat or not) is not affected by the magnitude of the external flow as long as it is kept constant between the two situations.

Lab tests (indoors) in addition to convenience has the advantage, that they occur in a controlled environment (just make sure the tests are not done near a fan or an A/C outlet).

I am sure “Motorhead” can tell me a number of things, but until he has shown proficiency in the relevant disciplines, I prefer to rely on my knowledge or somebody who do master the disciplines and are willing to share. On that subject, it appears that “ausgeflippt951” has quite good insight into heat-exchanges and the physics behind. I concur with him that color should be of minor importance, since color is a relevant concept only in the visible spectrum, while the IC at the temperatures we are talking about, will radiate only a little and mainly at a wavelength about 10 times the visible range (IR spectrum).

“Further, the examples of "heat dissipating" coatings mentioned are misnomers, as they are not applied on forced-convection systems.”
Get a grip, look at post #10 and tell that to “f1rocks” or try to weasel out of the fact that calipers and intake manifold are “forced-convection systems”.

Btw, it is not heat change that cracks rotors, it is the temperature gradient grad(T) = (∂T/∂x, ∂T/∂y, ∂T/∂z), which due to thermal expansion induces stress large enough to exceed the tensile stress of the material. The analysis may in some cases also be complicated by local plastic deformation at elevated temperatures with subsequent cooling.

Laust

Oddjob

I want to see how the intercooler core will be coated with a bottle of this exothermic stuff?

Coating the outside of the intercooler is somewhat irrelevant. The heat transfer surfaces are the core fins for the outside air, and the channels for the charge/intake air on the inside. Good luck getting those surfaces covered with any uniformity.

I dont see a way of doing it, w/o completely submerging the IC in a bath of the coating liquid (and most coatings I am familiar with are a dry powder particle coating) - but with submersion, you would run the risk of decreasing air flow due to blocked/plugged passages.

Trucho-951

Laminar flow, turbulent flow, boundary layer, heat transfer coefficients, Nusselt number…. It’s coming back to me now….oh, wait… Nope, that was just gas…sorry..