Car AC theory question

Ashton Crusher · 2013-03-12T23:38:38+00:00

AC condensers (the part that's in front of the radiator) can be purchased in bare aluminum or painted black. The purpose is to transfer heat to the air. It seems to me that for maximum heat transfer the best choice would be the bare aluminum. If it has paint on it it seems like the paint would act as a thin insulation and reduce it's effectiveness at transferring heat. Since so many of these are painted there must be something wrong with my thinking OR the insulating effect must be very very minimal. The same question could be asked about the regular radiator too, some are bare aluminum and some are painted black. I have heard in the past some talk about "black bodies" but since this is not floating out in space and merely "radiating" heat passively in a vacuum but is also (mostly) losing heat thru the movement of air over it's surface it seems like any surface coating that doesn't have a very similar coefficient of heat conductivity would be detrimental to that heat transfer. Anybody know anything specific about the effect or non-effect of the paint? Is it a 'special' paint? Does it just look like bare aluminum but it's painted with some clear paint so it's painted anyway?

Mar 12, 2013 83 Replies

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jim beam 13 years ago

i guess that would be a "specialty application". but how did you determine their material? when you say "fins", do you mean the grate-like arrangement at the back of a common refrigerator?

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The Daring Dufas 13 years ago

The condenser coil on the vending looks like a small radiator with a fan. The condensing unit is usually underneath mounted on a steel base with the compressor. The units can be slid out for servicing and or replacement. Take a look under a Coke vending machine or glass door Coke box and you may see the condensing unit. If you see a vender loading a soft drink vending machine, the door will be open and the condensing unit should be visible at the bottom. Ask the guy to point out the condensing unit for you. ^_^

TDD

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clare 13 years ago

Gas tight joints are not required between fins and tubes. The tubes are generally copper or tin-plated copper, with the find press fit to the tubing.- not even soldered in many cases.

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jim beam 13 years ago

true.

right

fins?

that's where i'm having the problem. steel is a poor conductor - it makes more sense to have the tubes steel and the fine fins made of copper or aluminum than the other way around.

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