Alexander Reeser wrote:
What do you think my chances of getting this information from apple look like???
Slim to none?
I don't think there is any liquid coolant in the iBook G3. I've been posting about iBook G3s since February of 2003, and have never seen anyone mention liquid coolant in them. Apple relies on dissipation of heat through the keyboard and case to keep the iBook G3 cool enough to continue operating, along with a small fan which blows past the CPU through the vents at the back of the iBook's case.
Once you move up to an iBook G4, the case gets hot enough that a laptop desk is necessary between you and the iBook. Even with an iBook G3, that is a good idea in order to facilitate cooling. Apple has never referred to their portable computers as "laptops." First, they referred to them as "portables" and, more recently, as "notebooks."
I'm going to pass on a link to this discussion to a fella who rehabs old iBooks for use in schools. He's been digging into the guts of them for years, so he may be able to answer your question more definitively.
As far as deconstructing is concerned, you probably have this link, but here goes, anyway:
Thanks for the response. There IS liquid in the heat pipe that is attached to the heat spreader on one end, and the heat sink on the other; though it isn't what is normally thought of as "liquid" cooling). It's a copper tube, and usually filled with some sort of working fluid: water, ammonia etc under a vacuum and it uses the latent heat of vaporization to remove heat and transport it to the heat sink where the fan dissipates it. They are actually quite common in laptops because of their efficiency and zero maintenance and have been around for some time. I could speak generally about it for my research, but I'd like to know specifics. If your buddy knows anything specific at all about the heat pipe, I would truely be grateful!
If you have an extra which you can cut open, working in a well-ventilated area, obtain a semi-closed container and put chlorine bleach in it until you get a good concentration of chlorine vapor. Place the tube in the most concentrated area of vapor and cut it open.
If you get what looks like white smoke developing around the opening of the tube, it's filled with anhydrous ammonia.
If you see nothing and the end of the tube appears to have a silver or white compound in it, it's filled with metallic sodium which melts when heated and transfers the heat. If you drop a piece of that in water, it should fizz and produce hydrogen.
These are two possibilities; there may be more.
(Metallic sodium is sometimes used in automotive high-performance engine valves.)
There seem to be quite a few of them up for sale on eBay.
You could try contacting a seller or sellers and see if they may know more about them.
Another search which may prove informative is this one.
It also could be helpful to know exactly which model you're talking about:
>I don't believe that the working fluid is metallic sodium
Well if it were that would be awesome but a bit dangerous if there were leaks.
Never seen leaks in those early iBook G3s or even the G4s.
So I'm thinking phase change or silicone based fluid. I'm not thinking anything under pressure.
There were leaking problems in the Power Mac G5s. These were the fastest Dual G5s and ran at 2.7 GHz:
These seem to work like a conventional auto type coolant system and that makes sense since they were designed by an automotive company.
The earlier Single/Dual G5s use heat pipes of the same design as those in the laptops.
In Googling heat pipe this:
says the fluid was
Can't imagine that the latter two would have been used because if that were the case there would have been a warning label on the laptop. Re: the warning label on current high efficiency FLD lamps and the label on the LiIon batteries.
All of the iBook G3s and G4s seem to have the same type of heat pipe.
So since you're deconstructing the laptop you should be able to easily tell what the fluid in there was. I would be interested in what you find.
After researching a little bit today, i believe that the working fluid is actually water. The thing with heat pipes is that they are under vacuum. This means that water could actually boil at anything above zero degrees (or room temperature), depending on what partial vacuum was chosen for the application. the choice of fluid has a lot more to do with operating temperature range than anything else, hence why sodium or mercury are very unlikely candidates in this case. Although water isn't really a "phase change material" in this particular case, you do have the right idea since there IS two phase heat transfer going on here (which is why this isn't "liquid" cooling if that makes sense). Silicone hasn't been used in any heat pipe application that I am aware of.
I'm actually more interested in the wicking structure inside. Unfortunately the computer is not owned by me, and I'm sure he would be annoyed if I took a hacksaw to his G3 cooling solution
I can at least ask
if i find out anything, i'll post
Thanks for the informative post. That makes total sense to me. There must be a limitation to the amount of heat that can be transfered since the last version of the Power Mac G5 went to that automotive radiator. The earlier design was actually quite massive.
I've got a few iBooks that are in parts. If you want I can send you a
heat spreader. Hit me up via my email if you like.
It's just amazing to me that they acquiesced to such extreme cooling methods for those CPUs....
Yeah I'd definitely be interested. If you have one of those small bubble wrap dvd mailers laying around I'll paypal you like 3 bucks if you don't need the part anymore. It would definitely be used in the name of science
If not, no worries, I'll figure something out!
I cut open the heat pipe today, and the results aren't surprising. The wicking structure is micro-grooved and I'm 90% sure the working fluid is simply water as I thought. the water is just below saturation temperature where it starts at the processor/gpu/bridge. any added heat when the cpu is active causes boiling which creates a pressure gradient. the vapor is then forced down the tube to the heat sink where the fan blowing on the fins condenses it back into liquid form. these micro-grooved structures are essentially wicks and allow the water to make its way back toward the processor via capillary action in order to be vaporized to start the process again. this micro-grooved wick with water is pretty much the simplest (cheapest) form of heat pipe you can have so it's understandable why apple used it. we're not exactly dealing with super-high heat levels
"A heat pipe is a hollow tube containing a heat transfer liquid. As the liquid evaporates, it carries heat to the cool end, where it condenses and then returns to the hot end (under capillary action, or, in earlier implementations, under gravitation). Heat pipes thus have a much higher effective thermal conductivity than solid materials. For use in computers, the heat sink on the CPU is attached to a larger radiator heat sink. Both heat sinks are hollow as is the attachment between them, creating one large heat pipe that transfers heat from the CPU to the radiator, which is then cooled using some conventional method. This method is expensive and usually used when space is tight (as in small form-factor PCs and laptops), or absolute quiet is needed (such as in computers used in audio production studios during live recording). Because of the efficiency of this method of cooling, many desktop CPUs and GPUs, as well as high end chipsets, use heat pipes in addition to active fan-based cooling to remain within safe operating temperatures."
Richard, I don't know if this helps you with your G5 cooling issues since i do beleive the G5 uses actual liquid cooling in the traditional sense (heat exchanger with EG/water). liquid flows at a positive pressure to cool using sensible heat without boiling where a heat pipe like this is under a vacuum (negative pressure) in order to facilitate the boiling process to cool via latent heat. really they are 2 very different processes... I don't know why they didn't use a dielectric coolant to prevent these G5 leak reliability issues they had. there's less heat removal capacity, but at least if you get a leak the whole system isn't destroyed.
I hope this information helps you out in some way though!