Intercooler Thermo Fan

[JETURBO]

^^^ dont know if srs ^^^

[Mrs Jeturbo]

what about a thermo fan for dif bush...

might cool them down and stop all the dif Bush issues on here?

[Panda Eyes]

thermo fan for fg bar.

[Benny]

As far as I am aware (and I am prepared to be corrected) the colour is only an issue if the heat energy is comming in the form of photons (light) eg. sunlight. In the case of sunlight, black will absorb more heat as it absorbs the photons. White will be coolest as it reflects all the colours of the spectrum. Differnt colours will have different effects depenging on which colours of the spectrum the absorb or reflect. This is subtractive colour (reflective). Not to be confused with additive colour where you are simply looking at light itself (such as a computer screen).

Cameron I'm not sure I agree with your theory here. It is a known fact in thermaldynamics that different surface colours and finish types have varying emissivity values. Emissivity being the relative ability of a surface to emit energy by radiation. A black surface has a greater ability to emit heat radiation as it's emissivity value is closest to 1, say 0.8 where as a polished reflective surface has a much lower value of say 0.2 making it a much poorer emiter of radiation. An example of this can be found in this youtube video I've grabbed quickly.

Ok so it's not going to let me post a youtube link in this post no matter what I try.

Regards,

Benny.

Edited 26/01/13 09:21 PM by Benny

[Benny]

So in the instance of a radiator the best colour is actually matt black as this will dissipate the heat within much quicker than a polished aluminium radiator. The problem with black materials is they absorb heat just as well as they radiate it but when the black item is much hotter than it's surroundings then this isn't a problem.

Edited 26/01/13 09:31 PM by Benny

[Cameron02]

Hi Benny,

Thanks for the link, interesting stuff, looks like I stuffed up by only thinking about the visible spectrum. So my hypothesis is in tatters.

I will continue researching and let you know but so far........... In the example you have linked to the can is wrapped in "clear" magic tape. So colour does not enter the example. Magic tape is matt. Matt surfaces expose much more surface area to the outside (eg. draw a straight 10cm line between 2 points, then draw a wavy line between the same 2 points, our pen has travelled much further on the wavy line). So this example is showing how increasing surface area will allow more heat to escape. At the end he says if you have a shinny metal surface paint it a matt colour. He does not mention which colour so I think it does not matter as much as area. However Both "area" and "emissivity" are important parts of the equation for calculating "black body radiation". So it appears to be correct that colours that absorb photons more quickly (black is best) will also emit them more quickly (this is where I stuffed up as I was only thinking of visable light and not infra red).

I will continue to reasearch to see wether it is the matt or the colour which is having the most effect here. For example gloss black may be wosre than matt aluminium. Matt black is best. For our purposes we just need to make sure we dont use it near a heat source such as the turbo. So those people who polish the compressor housings will be reflecting radiant heat (good) but also not letting a lot of heat out (not so good). Not sure of end result yet.

[dustyae86]

You're an engineer of some sort aren't you?

[BRK]

ohhhhhhhh fer chrissake...... this thread is completely out of hand! Set up the fan and report the results PLEASE !!!!

[Cameron02]

Surface effects

Lighter colors and also whites and metallic substances absorb less illuminating light, and thus heat up less; but otherwise color makes small difference as regards heat transfer between an object at everyday temperatures and its surroundings, since the dominant emitted wavelengths are nowhere near the visible spectrum, but rather in the far infrared. Emissivities at those wavelengths have little to do with visual emissivities (visible colors); in the far infra-red, most objects have high emissivities. Thus, except in sunlight, the color of clothing makes little difference as regards warmth; likewise, paint color of houses makes little difference to warmth except when the painted part is sunlit.

The main exception to this is shiny metal surfaces, which have low emissivities both in the visible wavelengths and in the far infrared. Such surfaces can be used to reduce heat transfer in both directions; an example of this is the multi-layer insulation used to insulate spacecraft.

The above is lifted from WIKIPEDIA under "thermal radiation"

[Cameron02]

You're an engineer of some sort aren't you?

NO, not smart enough, or patient enough.