By Joel Johnson at 5:32 am Fri, Feb 29, 2008
Doesn’t this present some sort of Grandfather Paradox, to which I am probably over-thinking? If the fan runs on the processor’s heat, but the fan’s main purpose is to stop the processor from getting hot, if it cools the processor where will the fan get energy to run, and so on and so on?
You are over thinking it. This is just converting some of the heat to a differnt form of energy. Imagine a current heatsink has to get rid of X heat. Right now, all that X heat has to be moved from being thermal energy in the heatsink to being thermal energy in the air.
Now imagine this. The heatsink converts half of X into kinetic energy, first in the fan and then in the air, leaving only half of X that needs to be transfered to the air as heat.
Kurtmac, the fan and heatsink probably don’t remove heat fast enough for that to happen. But if it did, and the fan stopped, it wouldn’t be a problem – since the fan would restart as soon as the heat built up again. Think of it as a temperature controlled fan: the more heat is applied to the system, the faster it likely spins.
That’s all conjecture, though.
The more dangerous scenario is: what if the other components in the computer heated the air up to the same temperature as the heatsink? Wouldn’t there be no heat exchange to move the fan, thus causing it to stop? Well, then I guess the heatsink would get hotter and it would then start again but at a reduced efficiency/effectiveness.
So I think you need to make sure the case itself is well ventilated, too!
But on the plus side, the fan will draw cooler air through the heatsink attached to the cooler side of the Stirling engine. And the case’d need to be ventilated _anyhow_, whether it’s self-powered or no- a heatsink doesn’t do much good unless there is a temperature differential.
+1, although I’ll bet the maximum acceptable surface temperature for the CPU is so much lower than expected air temperatures that you’d have ton of other problems first if the air in your PC got that hot.
It looks like a toilet.
Go Stirling Cycle!! Woot!
Always like to see waste energy recovered. Good show!
Codeloss, it sure does! It must be the toilet for those little drinking bird kinetic toys.
( http://en.wikipedia.org/wiki/Drinking_bird )
Fan slowing shouldn’t directly be a problem, since if there is insufficient heat to power the engine, the chipset will be by definition cool enough for safe operation. However, this leads to a real problem, which is that it is uncommon for a Stirling engine design to be self-initiating. So, you need a kick-start upon boot-up and if it ever stops.
On the other hand, large scale production of these little devices might also create a lot of hobbyist interest, since they could also be used as micro-mini gensets.
to start the sterling youd need to either have a electric motor or do it manually so basically its a more complex more expensive fan. a solonoid and a small electric motor with a rpm sensing device could engage it but it is still more complex than just a regular electric fan, maybe itll make a laptop run for 10 seconds. got to love overengineering.
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