IPSC

Ok one of my other interests in life is the world of firearms. I don't simply collect and own guns but I compete with them. To that end I spend a great deal of time modifing them as well. One of the things I have gotten guite good at is the coating of componets with teflons of various properties.

So this company that supplies me with these coatings calls me up the other day and asks if I would like to try and new coating they have developed for use in areas where high heat disapation would be ideal.

An exothermic coating as it were. Primaily for use on barrels and more importantly suppresors that routinely reach 900 degrees.

"Hummmmmm" I say "sure why not?" So up shows a bottle of the stuff and I am thinking the whole time... intercooler...

So how would I go about testing this stuff? I am thinking of simply coating some aluminium and heating it up. Then with a laser thermometer measure it over time, then repeat after it is coated. See if this stuff works or not?

Any suggestions for my method of testing?

IPSC

Ben Z.

For heat dissipation you basically want something that is a poor insulator, and a good radiator. Something black and thin would work well. Ceramics are usually pretty good insulators.

IPSC

From what I understand this mix was actually a mistake as they were trying to make something to compete with all the other header coatings out there and stumbled on this. It comes in different colors but I chose black.

IPSC

Ben Z.

The way you proposed to test it might be an issue. I'm pretty sure your laser thermometer relies on the emissivity of the surface being a constant value. Just the act of painting a metallic surface black would change it considerably. You can demo this to your self by sticking a piece of electrical tape to any surface and shoot the tape and the area right next to it.

I wish I could give you a better answer, but I'm not really that well versed in heat transfer. Tell me you want to coat something with a ceramic or metallic layer and I can help you, though.

IPSC

I can do the coating part. I was going to sand blast both pieces as a way to increase surface area just a little and coat one and not the other.

Intersting I will try that with the laser thermometer.

So maybe direct contact with a regular thermometer that can read in say the 250 or 300 degree range?

IPSC

2bridges

IPSC
So I am curious -
- won't claim to be the most educated with thermodynamics, but I cannot think of any benefit.

The aluminums ability to transfer heat is the fundamental principal for intercooler heat exchange to cool intake charge. You think a ceramic based coating would improve the aluminum's ability to "exchange" heat? I think exactly the opposite.... will insulate heat and make less effective exchange

am I missing somthing

RKD in OKC

That reminds me of my 928 days. There was a discussion on the flow through the intake tubes that run from the front of the car to the air filter. It progressed until someone mentioned that the dimples on golf ***** reduced their air resistance so they would fly farther and that maybe the dimples would improve the flow thru the tubes. Almost immediately someone posted that they had filled their intake tubes with golf ***** and it didn't help the flow thru the tubes one bit.

KuHL 951

First thing I would do is make sure it's compatible with aluminum. Sounds like the coating they envision is for tool steel if it's made for firearms. It doesn't take much to upset the natural passivation of aluminum with acids or alkaline solutions. You might want to try it on a piece of bar stock first for your heat test...just a thought. Ceramic to dissipate surface heat doesn't make sense to me either.

billthe3

IPSC never said it was ceramic, did he? All I see is Ben Z. talking about ceramics.

f1rocks

I use a heat disipating coating on my calipers and intake.

You can test by taking one caliper, coated, one uncoated. Put them in the oven at say 400F. You will see about a 20 percent difference in temperature at 3 minute intervals as the coated unit will throw off heat before becoming totally saturated with heat.

I don't notice a huge difference in brake performance but I'm not the best on the track at extracing maximum performance yet anyway.

The intake does stay cooler after a hard track run than my uncoated intake did.

RKD in OKC

From what I understand most coatings for aluminum heat exchangers are for corrosion resistance. The increased thermal transfer is supposedly from the combination of the coating having both a higher transfer rate than aluminum, and increasing the surface area of the aluminum by filling in the surface irregularities that the air molecules would not reach due to boundry layer flow dynamics. Mostly these coatings reduce the loss of heat transfer and cleaning maintenance cost due to oxidation of the aluminum.

The most efficient of this type of coating would be a diamond coating grown on the aluminum surfaces. Diamond is the best thermal transfer material because it transfers heat as a light wave. The heat transfer happens at almost the speed of light. This might improve the heat transfer from the air to the aluminum some, but it would not improve the heat transfer rate through the thickness of the aluminum itself. The cooling gains would be greater than 0, but I don't think it justifies the cost of coating and diamond coating is pretty cheap these days.

If these coatings worked that much better, race and factory intercoolers would be all over it I'm sure. If you don't think so, look at the gains vs cost of the Variable Gate Turbo in the new 911 Turbo. VGT have been around for a long time in desiel applications, only now has materials technology to endure the higher temperatures of gasoline applications gotten affordable enough to make a gasoline VGT, and it still ain't cheap.

IPSC

Good points all. You see before I go taking my intercooler out and then go through the time and trouble to coat it I want to test this stuff. It does supposedly have a ceramic componet to it as I understand it. My thoughts are these.This stuff is doubtfully some magic bullet to suddenly increase intercooler effeciancy a great deal but since I got this stuff for free, I "figger" why not try it? I just want an idea of a decent way to test this so that I can make an informed decision to procede or just use this stuff on my guns and call it good.

F1 Rocks, what product are you using?

IPSC

Blackwater

It seems to me that the product would have a stabilizing effect, more than a cooling effect. It may help tuning by providing a more stable environment rather than the environment of extremes of cold and hot currently experienced.

Laust Pedersen

Strange, everyone seems eager to speculate on (predict) the efficacy of the method instead of answering the question posed, namely finding a method for testing if the coating works as intended.
Here is my simple suggestion for a “kitchen table test” (easy to do and not too messy):

Materials: Two* intercoolers (one coated, another uncoated), a hairdryer/heat-gun, a thermometer, couplers/fixtures to reliably connect hairdryer/heat-gun to IC inlet and thermometer to outlet and pen and paper.

1. Clean both ICs externally and internally to be as identical as possible, then coat one IC
2. Fix the hairdryer/heat-gun to the IC inlet with one of the couplers/fixtures
3. Fix the thermometer to the IC outlet
4. Position the IC so the external airflow through the fins is vertical (natural unforced convection cooling flow)
5. If possible** set the hairdryer/heat-gun temperature to a realistic value (about 200F),
6. Start the hairdryer/heat-gun
7. Wait until the exit temperature has fully stabilized
8. Then record the result (stable exit temperature)

* One IC can be used by first doing a measurement on it uncoated, then coat it, then repeat the measurement and then compare the results.
** If the hairdryer/heat-gun has a fixed temperature, then design the inlet coupling so both hot and ambient air is mixed for an approximate 200F average inlet air.

If it works the stable outlet temperatures will be significantly different. To get a sense of the measurement stability it may be a good idea to first measure two uncoated ICs.

Laust

PS we have had this discussion before using thin black paint and black anodization, so I am more interested in the results than more or less well-founded opinions.

2bridges

Back on-topic: Nice suggestion Laust

Must agree only effective testing will have to be IC charge (change in air temp) not IC surface temp.

Best method I can think of:
two air temp probes - One immediately before IC, one immediately after
get solid baseline with non-coated IC, install coated unit and find out the real world effect.

Tricky part will be to reproduce cnditions as near as possible - ideally same day (temp,humidity,etc) and with car up to temp etc,etc