TL:DR Copper vs Aluminium cooling delta by surface area.
After waiting for AMD to get their new CPU's to market, I am in the prep stage of a build to replace my dying 3570k
Obviously not selecting specific parts yet in terms of components, but working out the 'best' cooling solution for the new system.
Custom loop vs CLC, as custom loop givers me option for copper rads, but in terms of price comparisons, a 360 aluminium rad is about the same price as a 240 copper one. I am after a quiet system (not chasing silence though) and if a pair of 120 fans on copper will be quieter than 3 on Aluminium then that is probably the way to go.
If specifics are needed, its a toss-up between a Kraken x62 (2x140) - Thermaltake 120x3 - and EK custom loop(either 2x120 / 2x140 with Vardars). If the custom loop is only 5% quieter, but twice the cost, then thats probably NOT worth it.
Sorry if this is all over the place - work is bonkers right now and I'm on the tail end of a 85hr work week for the last 3 weeks straight. (1st world problems)
Many people seem to think that, but copper is still superior to aluminium, why people think this is the case might be cause aluminium feels like it's cooling down quicker after being heated, but truth is it has a lighter mass and can't store the same amount of heat compared to copper, thus cooling down faster. Aluminium is cheap, that's why rads use it alot.
Careful, if using a aluminum radiator you must be mindful of dissimilar metals in the loop. If you have a copper block with an aluminum radiator you are in for some galvanic corrosion later down the line no matter how much glycol you use.
If you look at the trend in water cooling you can see most companies moving away from aluminum and toward copper. I personally sought all copper components due to this reason.
Now for heat extraction I believe Aluminum cools more quickly than copper but copper has a higher heat capacity. The most contributing factor is how they are built. Aluminim can have a larger internal surface area and the fins typically make better contact with the tubes over copper.
This is simply not true. Aluminum is worse than copper, but it is much, much cheaper. You need to provide some hard science for me to accept that alu somehow transfer heat better to air than copper. The data on the materials does not agree at all. Also remember that alu oxidizes very quickly. "Clean" alu is not really possible in the atmosphere. There have been much work done on this in the auto industry/sector.
Copper is better, but more expensive and weaker (solder also play a role), so a alu rad is about as good and cheaper.
Edit: In a car that is. In a PC copper is preferred of course. Also we do not use the same techniques when manufacturing a radiator for a computer as for a car. Copper tubes may be too weak/expensive in a car for example, but is no problem in a PC.
Got your stuff mixed up, it is the other way around. Copper cools more quickly as it has better heat conductivity, about twice as much as aluminum. But copper has a lower specific heat (0.385 J/g 0C) compared to aluminum (0.902 J/g 0C). However, copper is much more dense than aluminum, about three times. It is also structurally weaker so you need thicker metal to get similar strength. This means a typical copper radiator still has higher heat capacity compared to a similar size aluminum one.
However, you need to join copper to other metals somehow (usually brass), traditionally this is done with lead solder. The solder joint is a weak point as it hinders heat transfer as the solder is much worse at heat conductivity compared to copper/brass. You can use other brazing techniques that doesn't have this weakness, more expensive though so not done much AFAIK (and I don't know much, lol). I need to look for water cooling radiators that doesn't use solder/use special brazing some time. Alphacool has radiators where the pipes are copper just like the fins (pipes are usually brass), so no solder problem.
So while copper is the better metal it is more expensive and harder to work with, so we use aluminum instead mostly. In a high end PC it would be very possible to only use copper, Zalman has made heat-sinks out of only copper once upon a time. Heavy, expensive and do not drop it please as it will dent/break easily.
Silver would be an even better metal, as it conducts heat a little better than copper. Thermal and electrical conductivity tend to follow each other. It also has worse specific heat and is just a tad tiny bit expensive :-)
Just look at home heating all copper and brass and that lasts for years. Like other people have said aluminium is cheap and light (light so all shipping costs reduced in the product chain) it isn't as efficient as copper at cooling. As for 240 V 360 cooling the extra cooling is very little difference (think about if both had two fans) well if it's the extra fan your after if you have fans both sides then you can get 4 fans on the 240 if you were that keen. It sounds like you are thinking of three fans on 360 aluminium is going to be louder than 2 fans on 240 copper and yes they probably would be quieter as you would need to run the two fans faster however you have missed the most important thing of all. The fans! Regardless of the rad size or material quiet fans are going to make the most difference! The bad news is they are going to be much more in cost than the difference in the rads. Tldr 240 copper 2 good quiet fans.
I've always heard that the reason that aluminum is a better choice for radiators because it is much less dense than copper, which somehow makes the transfer of heat to the air more efficient. I never looked into it much though. Obviously, copper is has a significantly higher thermal conductivity (like 50% higher, I believe), and aluminum is easier to work with/stronger as well as less dense (about a third as dense). How the density affects the transfer to air, I'm not sure. Would be interested to hear some info about it though.
It just seems to me that if copper was the definitive, better solution, that we would see top end coolers (the "cost doesn't matter" type of options) with nothing but copper. But we don't (there are some all copper options that I have seen, but they are few and far between iirc). That tells me that copper is not well suited for the task, or that at least that its improvement is offset by the cost and how hard it is to work with when compared to aluminum fins.
EDIT: I did come across this, which may very well be definitive proof that copper performs better than aluminum as fins.
Dissipation to air isn't a thing. Think of it as thermal conductivity everywhere: how a rad cools depends on how the surrounding material, in this case air, conducts heat from the rad to itself. I'll say it again: why aluminium seems to cool faster is because it has a smaller mass -> can store less heat (using simplified terms here) thus cools faster. You can test it by heating 2 similar bolts to temp x, 1 made of copper and 1 of Al. The Al bolt will cool quicker since it's less dense. But take 1 kg of copper and 1 kg of Al (assuming they have the same surface area (yeah i know)) and let them cool, the copper will cool faster.