8 ms·
Heat pipe – 250x faster heat transfer than copper
- deleted 2y ago[deleted]
- bdjsiqoocwk 2y ago> Modern CPU heat pipes are typically made of copper and use water as the working fluid. So there's water inside my laptop?
- supertrope 2y agoWater is the original coolant. Abundant, decent performance, cheap, non-toxic.
- dogma1138 2y agoNot only decent performance but the highest head capacity of all liquids, and it’s boiling point can be easily adjusted by lowering pressure if required.
- bumby 2y agoAmmonia tends to outperform water, but it's toxic. I believe it was used in some of the first refrigeration applications (and I think Einstein had a patent related to one).
- anfractuosity 2y agoI came across potassium nitrate + water being used for making things cold - https://cordis.europa.eu/article/id/36036-making-things-cold-a-history-of-science-technology-and-culture https://cordis.europa.eu/article/id/36036-making-things-cold... . Wonder if that could be used too?
- jaclaz 2y agoAbsorption refrigerator: https://en.wikipedia.org/wiki/Absorption_refrigerator https://en.wikipedia.org/wiki/Absorption_refrigerator Einstein refrigerator: https://en.wikipedia.org/wiki/Einstein_refrigerator https://en.wikipedia.org/wiki/Einstein_refrigerator The principle is still used in some refrigerating devices (typically hotel mini fridges and similar small units for RV's) as there is no need of a compressor (i.e. the device is completely silent) and also in some HVAC machines.
- dogma1138 2y agoWe aren’t talking about regurgitation but rather about heat transfer. Ammonia has lower heat capacity than water, and it’s nasty.
- bumby 2y ago>Ammonia has lower heat capacity You’re probably confusing gaseous ammonia, but the GGP said “of all liquids.” Liquid ammonia has a higher heat capacity than liquid water. Refrigeration is just an engineering application of the heat capacity of a working fluid (and I’ll let you guys why some of the earliest heat pumps used ammonia) >it’s nasty I clearly stated toxicity as an obvious downside.
- lesuorac 2y agoBut also corrosive.
- taskforcegemini 2y agounless distilled
- elcritch 2y agoAh distilled water is terrible for metal pipes. It’ll leach out metal ions from the pipes.
- tantalor 2y agoAnd steam!
- ikekkdcjkfke 2y agoI want a steam generator on my cpu now, whistle and all
- smolder 2y agoIf it has heat pipes/vapor chambers then yeah, it's like the chips are heating elements for a little low temperature, low pressure boiler.
- Sakos 2y agoInterestingly, heat pipes in a computer can corrode and leak the coolant (largely escapes as water vapor). Once it's gone, the heat pipes are basically junk. I've seen this a few times, wondering why the thermal performance was so abysmal (think 90-100 degrees celsius with low loads). It was only after completely replacing the heat sink or whatever assembly contains it that temperatures would be normal again.
- Brian_K_White 2y agoCorrosion requires a constant source of fresh oxidant. The water trapped inside a heat pipe cannot corrode anything. The tiny amount of free oxygen that was ever trapped inside gets consumed essentially immediatly and amounts to a relative handful of atoms on the inner surface. If a heat pipe ever corroded and leaked, it was manufactured with a leak to begin with, or was corroded from the outside.
- Sakos 2y agoI never said the coolant corroded the heat pipe.
- ungamedplayer 2y agoYour CPU pins rusting is a bigger concern then.
- Sakos 2y agoI never said it was a risk or concern or anything else in that direction. I was just pointing it out because I thought it was interesting. There was a time I didn't realize there was coolant in these heat pipes that could escape. Until encountering one where it had dissipated and, after some consternation and googling, realizing what must have happened to cause such terrible thermal cooling performance. Even if it does happen, heat pipes are among the cheapest components to replace (also the easiest). Does everybody just want to argue over nothing now?
- mystified5016 2y agoSometimes they use ammonia instead!
- Tade0 2y agoI recall stumbling upon this while trying to answer the question "can you tell if there's a risk of fire on one end of the extension cord by measuring temperature on the other?" Turns out that no - at least not for any extension cord of practical length and design. Copper is a great heat conductor, but not nearly as effective as a dedicated heat pipe. You'd have to run it along the length of the cord to get a temperature reading above noise.
- hengheng 2y agoWe once did math on finding overheating FETs with an on-PCB temperature sensor. We came to the same conclusion as you. Our supplier advertised a sensor, which we found eventually on the other end of the PCB. The reaction time would have been five or ten minutes if at all, essentially the whole device would burn down and eventually it would take the sensor with it. Turns out, the sensor would had to sit directly opposite the FET on the PCB, and there had to be a plugged via going straight through for sufficient thermal coupling. A lot of the physics boils down to simple aspect ratio, and normal vias are really thin. (The real solution would have been putting the sensor on an FPC, and to glue onto the transistor. The real real solution was to make sure the part didn't blow up in the first place, which was much easier to do.)
- agumonkey 2y agoI was quite surprised to see the complexity of inner heatpipes https://www.powerelectronictips.com/wp-content/uploads/2020/12/Laptop_CPU_Heat_Pipe_Cross_Section-1.jpg https://www.powerelectronictips.com/wp-content/uploads/2020/...
- tetris11 2y agoI can't work out if that was sarcasm or not, but isn't that just corrosive buildup?
- pipe2devnull 2y agoNo, that’s the wick. It lets the condensed water move by capillary action.
- tetris11 2y agoah thanks for the context
- deleted 2y ago[deleted]
- deleted 2y ago[deleted]
- deskr 2y agoThe Action Lab did a very informative and interesting video on Heat Pipes: https://www.youtube.com/watch?v=OR8u__Hcb3k https://www.youtube.com/watch?v=OR8u__Hcb3k I had seen those things inside laptops, but always assumed it was just ordinary copper rod.
- solardev 2y agoIf it's water, how does it turn into vapor below 100 C? Is there some pressure magic in the heat pipe?
- lelanthran 2y agoIf it's water, how does it turn into vapor below 100 C? Is there some pressure magic in the heat pipe? Yes. The air is partially removed before sealing, resulting in the heat pipe interior having a lower pressure than ambient air pressure.
- solardev 2y agoAh, thank you!
- gssa 2y ago[flagged]
- rajnathani 2y agoAlso, making custom heat pipes from China is really quick and inexpensive. We trial-ed some for one of our projects, all we had to do was send the CAD drawings, and they did the rest. The thing is that they didn't have to make tooling for samples-level of quantity, and thus it was very inexpensive to make for trying things out. The company we used is called Soodeco Metalworks, but we changed our design to have no cooling as it wasn't required, thus we never went mass production for it.