also, you need to look at the reflectivity/absorbtivity of the material in
the proper bands - visible is not where most of the radiated energy goes
with a radiator, it's in the low part of the IR band. Also, most cooling is
by convection, not radiation, so removing the paint offers a lower thermal
resistance to the air


"Steve W." wrote in message
...

wrote in message
ps.com...

Derek wrote:
Most cars tend to have black radiators, condesors etc. but I've
noticed some oil coolers and sleeve type air units use silver
(aluminum).

Is this just a styling issue with cars and refridgerators etc., or
is
one colour better for radiators?

Similarly, all the evaporators I recall seeing, have all been in
their
raw metal colour. Does it make much difference at the end of the
day?

Thanks.

I've got a really old book on steam heating and plumbing that had a
write-up on the effects of color on radiators. Turns out radiators
painted black or a dark color were slightly more efficient than
unpainted or light-colored ones. The difference was very slight in
those tests and at the temperatures they were using. Probably added
manufacturing cost has something to do with it, coupled with the very
slight efficiency boost that can be had from black vs. as-is. On the
wrecks I've robbed,radiators were uniformly black, A/C components were
in the white. Might just be tradition on the radiators' color.

Stan


Early radiators were brass and copper. The black paint was on them to
help control corrosion and hide the radiator from view from the front of
the auto (hiding all the solder joints was also a big thing). Many
newer vehicles have bare aluminum BUT on many of them you cannot see the
radiator from in front of the vehicle anyway since many are now pulling
the air from the area below the front bumper.



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