Dudeland

Paint the Rad and condenser black or not

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I would normally say it didn't matter what colour your rad or condenser is but take a look at the video below from MCM (mighty car mods) and tell me this wouldn't make a difference.   I realize it is an intercooler but it is the same principle. 

 

 

 

 

 

 

 

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Everything has a radiation effect but the radiator transfers heat by convective cooling.  If it were radiation was primary, the color would affect the exhange rate.  But it's a finned fan heat exchanger and it has been misnamed forever.  So don't wasted the paint.  This is physics 101.

Edited by jimk
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I am thinking that the radiative effect is most important when air flow is low in stop and go traffic. The heat lost through convection will not change but the radiant heat would if the rad gets painted.



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Using the wrong (thick) paint will reduce air flow. There is a thinner spray paint available just for radiators....err....heat exchangers.🙂

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Adding paint adds insulation to the heat exhange surfaces.  Have you deducted this effect from the radiation gain and convective properties?

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I'm an engineer at a radiator company and our plant primarily manufactures radiators and intercoolers for tractor-trailer trucks.  We paint some customers cooling modules (radiator + intercooler + HVAC condenser) black for aesthetic purposes and some we do not.  For the projects where paint is requested, we've tested coolers back to back in our wind tunnel (first unpainted, then painted), where we have a HIGHLY controlled environment (coolant temperature, pressure, flowrate, air flow temperature, pressure, flowrate, humidity, etc. over a complete range of operating conditions) and the difference in heat transfer is always less than the the noise of the system, which is just what the video here shows also (100 vs 97 degrees is certainly within the measurement error of that setup).  While they are also correct that radiative transfer does increase with black paint, this actually doesn't matter in the real world, because there's *ALWAYS* airflow across the intercooler (radiator and/or condenser fans on, breeze, etc.) even when stopped, and the convective transfer so far outstrips the radiative that it becomes negligible.  So actually a decent video with reasonable data, but the conclusions were still off a bit.  Again some OEMs still pay for paint for aesthetics, like when you can see the heat exchanger through the grill, but that's it.  Also true there isn't really a downside (convective transfer is not worsened) aside from cost, so take the OEM route and paint it if you like how that looks, but it won't affect performance at all.  If you want better intercooler performance at peak torque when accelerating from a standstill with very little airflow, then you need a liquid-to-air intercooler, but this then requires a special low-temperature radiator to cool the coolant enough and you better darn well make sure it doesn't leak, because coolant dribbling into the intake tract can quickly spell hydrolock!

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6 minutes ago, AustrianVespaGuy said:

I'm an engineer at a radiator company and our plant primarily manufactures radiators and intercoolers for tractor-trailer trucks. .... and the difference in heat transfer is always less than the the noise of the system...

 

Outstanding - I like real-world test data. -KB

Edited by kbmb02

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8 minutes ago, kbmb02 said:

 

 

Outstanding - I like real-world test data. -KB

You guys poured cold water on the subject.  I wanted to see how far the hair splitting would go!

Like I said, don't waste the paint.

Edited by jimk
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I can see the insulation point of view. However with additional paint wouldn’t it create slightly larger fins? I’d assume the larger the fin would absorb more air, causing better cooling. while moving of course I agree in traffic it’d probably not be a good idea.

Anyways they look cooler black gives it a more stock look rather than having some chrome shining out from under the bumper/grills.

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21 minutes ago, Dudeland said:

Only time will tell if I am right. 

I don't recall seeing in this thread where there was a problem before.

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59 minutes ago, Dudeland said:

So here is my answer. Only time will tell if I am right. IMG_2497.thumb.JPG.83516a09948b415c94b9cef1b75e0b3a.JPG

 

Overspray, just like from the factory!  ( ; p)

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All fine, but if the color of the radiator and condenser on your ‘02 means the difference between overheating and not overheating, I’d suspect you have more substantive cooling system issues than the choice of color.... 😉

 

Regards,

 

Steve

 

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