7 ms·
Is the thermal conductivity of helium actually relevant to hard drives? Like what kind of hot spots and transfer rates are we talking about?
by tedunangst 9y ago
Is the thermal conductivity of helium actually relevant to hard drives? Like what kind of hot spots and transfer rates are we talking about?
- HankB99 9y agoFWIW utility generators are cooled with hydrogen to reduce windage losses and promote cooling. Hydrogen is probably lower viscosity and higher thermal conductivity than helium. It's also very hard to contain due to the small molecular size and has the widest flammability range of any gas with which I'm familiar, making it an interesting gas to work with. ;)
- frandroid 9y agoThe utility generators probably don't worry too much about leaks, since they can just refill with new, abundant hydrogen, too. It would be amusing to have a hydrogen-cooled hard drive for which you'd have to regularly refill the water tank so that it could generate more hydrogen for itself. :)
- deleted 9y ago[deleted]
- tzahola 9y agoYeah, and it would have a little Bunsen burner to safely get rid of waste hydrogen!
- HankB99 9y agoYes, it's the hydrogen that leaks out that's the problem. I was told that the way to find hydrogen leaks in plant piping was to walk the line holding a corn broom over the line. When it bursts into flame you found the leak. In an enclosed space it can form an explosive mix with air if it doesn't ignite before it accumulates.
- fnordprefect 9y agoIsn't there also a potential problem with hydrogen embrittlement (depending on what materials are exposed) that you avoid with helium?
- HankB99 9y agoI don't know, but it seems possible. The only references I recall about hydrogen embrittlement were with steam boilers at high temperature and pressure. I suppose like most engineering solutions it comes down to the various tradeoffs between cost and effectiveness for hydrogen vs. helium.
- mattrices 9y agoHe has a conductivity coefficent K (W/mK) = .151 and air = .026. Since everything else in heat flux eq is linear, approximately 5x rate of heat movement per degree that the HD is heated beyond surrounding air is expected.
- tedunangst 9y agoYeah, I can read a table of figures too, but what does that mean in the context of a hard drive? What percentage of the heat generated by the write heads (or whatever) is conducted away via air?
- mattrices 9y agoThat is a function of the design implemented. Since you can read a table of figures you can probably also plug them in the heat flux equation in with your own guesses at air gap distances and surface area. The relevant info is that 5 times the energy per degree difference are conducted, that is why any hot spots from friction are smoothed.