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Posted by: Mueller Mar 7 2004, 03:22 PM

Just wondering if anyone has seen this or expermented with such an idea??

LN Engineering has (or had, not sure if they still make 'em or not) iron cylinders pressed into an aluminum fin arrangment.......cost wise they are decent, but I know the cooling of thier "nickies" is far, far superior

Now copper is even better than aluminum at getting rid of the heat, so I thought that would be an interesting material to try out....of course the cost and softness of copper would not make it an ideal material for the entire cylinder...........


thoughts???

Posted by: davep Mar 7 2004, 03:38 PM

Well, copper is a better conductor than aluminum or iron, but then silver and diamond are even better than copper. Diamond should have better wear characteristics than the iron for bore material, and would also offer the benfit of watching the combustion process. Now as far as cost and thermal rates of expansion, I think we run into problems. I have worked with copper fins on an aluminum heatsink before without noticable improvements. There are several problems with dual materials in this applicaton. First is the introduction of a thermal interface between the two; that tends to be the biggie. Next is differing rates of thermal expansion; tends to cause separation or cracking.. Third is galvanic corrosion. In my experience, as a thermal scientist, improvements in airflow and surface area would provide bigger results for less cost.

DaveP

Posted by: mikester Mar 7 2004, 07:51 PM

In my computer I have a pure copper heat sink on my CPU. with a large case fan over it running a bit slowly (quiet). It does a great job of keeping my cpu cool. Much better than those crappy aluminum heat sinks with the fan bolted directly on. The thing is, the aluminum is failry light and the copper is about 20 times heavyer. Seriously - H-E-A-V-Y.

Posted by: Mueller Mar 7 2004, 09:07 PM

to help stop/control this how about using a heat sink compound(silver instead of silicon) in between the iron and the copper? Most of these are good for 200°C

for the differing thermal expansion, the fins could hinged or have springs to compensate for the expansion/contraction.....

i guess I was out it the sun too much today

Posted by: Bleyseng Mar 7 2004, 09:10 PM

How about gold or silver fins? They don't react with iron.

Geoff

Posted by: J P Stein Mar 7 2004, 10:02 PM

[QUOTE=Mueller,Mar 7 2004, 07:07 PM] [QUOTE]
i guess I was out it the sun too much today
[/QUOTE]
Really?
Seemed like one of your "normal" days to me

Posted by: Dave_Darling Mar 7 2004, 10:47 PM

The "Biral Babies" turned out to be too expensive to make. LN did one small run of them, but stopped and won't be offering them again soon, from what I hear. Charles said he was considering using a cheaper, lower-quality manufacturing method, but that he didn't think it was worthwhile to cheapen the product like that.

--DD

Posted by: maf914 Mar 8 2004, 07:42 AM

I have never heard diamond mentioned as a good heat conductor. But as you note, the cost would typically keep it from being used for one. I would have assumed it would conduct heat in a manner similar to glass.

Mike

Posted by: banderson Mar 8 2004, 08:01 AM

DATA:

Thermal conductivity, BTU/hr-ft-DegreeF
205---Copper, 145 (free machining)
104---Aluminum, 6061
28-----Grey cast Iron

Thermal Expansion
9.9---Copper, 145 (free machining)
13----Aluminum, 6061
5.8---Grey cast Iron

Summary, Aluminum is 5 times more conductive than iron. Cu doubles that again. In terms of expansion, you have to plan for it in your bolts, but Cu would be less extreme than aluminum. $/lb-?

Posted by: Mueller Mar 8 2004, 08:56 AM

diamonds are 10 times more efficient than aluminum when it comes to conductivity.......

Posted by: maf914 Mar 8 2004, 09:23 AM

Interesting. How about other gem stones? Must be that crystal molecular structure. I must have missed the heat conduction discussion during my materials classes!

Mike

Posted by: davep Mar 8 2004, 09:39 AM

Other gemstones? Not that I'm aware of, and I try to keep up with thermal data on a weekly basis.
Yes, definitely the crystal structure. Some forms of carbon are very conductive, but it can be very directional.
As far as thermal grease, that adds another interface and a lower conductivity material. The only use for such greases is to fill in the microscopic void (air bubbles) between surfaces. If the aluminum were cast onto the iron cylinder there should not be much to worry about. They have used this technology for years, and it is not too popular now for good reasons. I'd have to say that the "Nickies" are the state of the art. You only get what you pay for.

Mike, glass is a liquid, very viscious but a liquid. Diamond is a crystal. Very different in so many ways. Do not confuse crystal stemware with cheap glass imitations. They are very different.

Posted by: fiid Mar 8 2004, 10:44 AM

Diamond is a pretty damned cool material.

I read in Wired a few months ago that there are a couple of companies that specialise in manufacturing synthetic diamonds, much to the annoyance of DeBeers. They tend to produce purer diamonds that may at some point be viable for more industrial applications like cylinders, etc. There is also some interest in producing integrated cicuits based on diamond, which will also gain from better heat dissipation.

Maybe in the next 10 years we will see a time when it is not utterly impossible to have diamond cylinders!

In that time, I'm sure Mueller will get the appropriate machinery for his workshop :-) LOL

Posted by: maf914 Mar 8 2004, 12:04 PM

Glass a liquid? You're right. Now I remember. That's why old glass panes distort, they're flowing.

I figured I was wrong about glass being a similar conductor to diamond when I started to think about the crystalline structure of diamond.

Now, stemware. What is quality crystal stemware if not glass? I always thought the word "crystal" was used to denote high quality glass ware.

Mike

Posted by: Dave_Darling Mar 8 2004, 12:42 PM

I have read recently that the "glass is a liquid" is incorrect. A quick Google search turns up, among other things, this link:
http://www.glassnotes.com/WindowPanes.html

Isn't glass actually an amorphous solid? Different from a crystal, certainly, but not a liquid.

--DD

Posted by: maf914 Mar 8 2004, 12:55 PM

Damn! Another urban myth bites the dust!

I like the statement "Half of the pieces in a window are thicker at the bottom, he said, but, he added quickly, the other half are thicker at the top."



Mike

Posted by: davep Mar 8 2004, 04:46 PM

I stand corrected. I've always claimed to be a "mad physicist", now you know the emphasis should be on the "mad". Heck, I even get angry sometimes!

Posted by: John Kelly Mar 9 2004, 08:07 AM

Steel can look like a liquid...(insert smirk)

John www.ghiaspecialties.com


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Posted by: maf914 Mar 9 2004, 09:42 AM

John, I bet the birds in your yard get PO'd when they visit your bird bath!

I have two bird baths in my backyard that get a lot of bird and squirrel traffic. Takes a bit of maintenance to keep them clean and full of water though. The steel would solve that problem I guess.

Mike

Posted by: John Kelly Mar 9 2004, 12:47 PM

Hi Mike,

I'm going to have to put out a real bird bath too I guess.

John www.ghiaspecialties.com