I wouldn't have thought that it would make much difference, most of the heat will enter and be trapped by the glass, while the metal is all backed by an insulating interior decor.
Seats are indeed another matter. Back in the '90s I had to travel from Benghazi to Tripoli and then on into Tunisia, in an old Mercedes, with no air-con and vinyl seats, at the height of summer - it was an experience not to be repeated!
It's the steering wheel that bothers me!
With some its a fashion/fad thing.
With others its a tradition, particularly with official cars and hurses etc.
And a bugger to keep clean, they show even the slightest dirt.
Trouble with white is that it shows the shit stains when you have an accident.
It does actually.
Nope, even with modern large windsceens.
The insulation is quite poor.
What I was trying to find out was if the following is true.
If metal A conducts through itself twice as well as metal B, then metal A will conduct to air twice as well as metal B.
The rate at which heat is transferred to the air surrounding depends on the thermal conductivity of the material, which is a measure of how quickly heat can move through a material. Copper has higher thermal conductivity than aluminium, meaning that copper heats up faster but also cools down more quickly.
Painting a metal does not affect its thermal conductivity because thermal conductivity is a bulk property of the material. However, painting a metal can reduce heat transfer away from the metal by convection.
Matt black is best, shiny plating the worst. Which is why all bathroom towel rails/radiators are chrome plated...
That is what I was wondering - if just because copper conducts more heat through itself, whether it would therefore conduct it to air better.
All CPU coolers use heatpipes. Well proper CPUs I mean. 24 cores upwards kinda thing, not a silly little 4 core Celeron.
Which I used, but if you don't know what something is called....
Emissivity is presumably radiating heat. I was thinking more of a heatsink with fins, and air forced along those fins by a fan. So it's the conduction of heat from the metal to air which matters?
Not really.
It depends on the thermal conductivity of the air. For straight transfer It depends on the emissivity of the surface. for radiation It depends on the surface are for everythiu g It depends on the speed or airflow over it for forced cooling or convection
The thermal conductivity of thematerial only affects heat trnsfer from the heat sourrce to the surface.
which is a measure of how
That however is not the issue.
Physics covers a wide range of topics. I did among other things, quantum mechanics, astrophysics, digital microelectronics, power grids, and materials engineering.
You can see as far as bulk conductance goes, the range is pretty large. And maybe a dangerous source of speculation. What we want to know, is the thermal resistance, at a reference air velocity. Since you are working with inefficient ideas, you're going to need a damn good sink. Even your rectifiers could overheat. The 200 LFM below, is a typical spec point. 800 LFM is a practical limit to forced air (no spec shown).
Since copper sinks are so hard to find, I started the search with copper, to narrow the field. I got lucky. Two lines in the datasheet, contain two materials we can compare.
Digikey catalog. SKV4545225. The high fin density means these are intended for forced air usage. Larger air channels are used for convection coolers. The items are specced for both usages. You can see the huge improvement forced air makes.
The reason I picked a 22.5mm high HS, is because longer fins add cost, but they don't add too much to cooling. When the fins are as thin as the example, the thermal resistance discourages "tallness".
And that's why heatpipes exist, because they conduct heat a distance, without a large thermal resistance.
And picking up a datasheet like that, is to avoid too many spit in the wind guesses.
The surface finish of items, makes some difference. Aluminum oxidizes and has (eventually) a rough surface. Copper also has issues, because plain copper can be fouled by chemicals. A nickel coat on the copper, spoils some properties, but keeps the surface pristine. Copper is hella expensive. Nickel is hella expensive. This is why nickel trucks are hijacked on the road. One nickel truck can be worth millions.
That's why the digikey catalog has, like a hundred thousand Al sinks. They're easy to extrude and cut to length. They charge a lot for them, the profit must be insane. What a time to be alive. With the copper, maybe they're machined instead of extruded. With the aluminum ones, the employees can go drink coffee, and the machine does all the work.
The Al ones will need some holes drilled in them, when the employees come back from coffee.
Putting thermal compound on sinks at the factory, is a pain in the ass. One of mine, used a pump and observation ports, to figure out when "enough" goo was present :-) I'm sure the kids had fun. Everyone probably ended up coated in thermal compound. A more common method, is thermal tape. If your sinks are light enough, the tape holds them on.
Arctic Silver has a thermal epoxy. It is *permanent* and it definitely keeps the sink on the top of a RAM chip on a video card. A usenet poster tried to remove one of those, and the heatsink ripped the plastic top right off the RAM. Which is a testament to how good the AS epoxy is. We would never do that in manufacturing, because our products had to be re-workable ("repair shop").
Paul
I suppose, but not good enough a reason for me to suffer.
Cloth seats are the most comfortable, and I don't think they get burning hot even in the summer, but because there are so few used convertibles for sale and the ones I've bought were in the high-end direction, they came with leather seats.
In one case on a cold winter day, to get something off the passenger side floor, I kneeled on a seat and cracked it in several lines. That wouldn't have happened with cloth either. Sitting spreads the load out so I've learned not to kneel on seats in cold weather, and it hasnt' happened again.
I haven't had vinyl seats since the 70's, and they were the black hot ones, and probably sticky when hot too.
Cloth seats seem to be low status, but they are the most comfortable.
Call me low status then. My car is a tool for moving me from point A to point B, comfortably and inexpensively.
So my question remains. Take two pieces of metal, metal A has exactly twice the conductivity (as in through itself) as metal B. Which of these is true?
1) Metal A conducts heat to the air exactly twice as fast. 2) Metal A conducts heat to the air faster, but not necessarily twice as fast. 3) We can't deduce this from it's conductivity.
I read something saying that doesn't actually make much difference.
Radiation is mainly infra red, perhaps black paint and white paint both radiate infrared the same? Or perhaps the colour of the paint only shows how well it reflects different wave lengths, not emits them.
What on earth would specific heat capacity and conducting heat have to do with each other?
And conducting to air is not the same as conducting within itself.
Stop being such a sissy.
You mean shorts. All pants are shorter than shorts.
Pants:
I buy whichever car is best, irrespective of colour of anything.
The heat simply adds to your bodyheat, so you sweat a bit for a while, who cares?
Just get naked.
And f****ng impossible to clean.
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