Cool as in Brrrr, Hot as in 'Thermodynamics'

"I once had a laptop that was so hot we used it to keep warm in the winter." "Well, I once had a laptop that was so hot it set off the fire alarms in the office." "That's nothing! I once had a laptop that got so hot I fried eggs on the disk drive." (Yuck!).

If you hang around Henry's coffee house as much as I do, you hear stories like this all the time. But Avik Ghosh, an assistant professor at the University of Virginia, tops them all: "If we continue at our current pace of miniaturization, these devices will be as hot as the Sun in 10 to 20 years." Which is why Gosh and fellow professor Mircea Stan are re-examining the Second Law of Thermodynamics that says, all else being equal, heat will transfer from a hotter unit to a cooler one until both have approximately the same temperature.

From what Ghosh and Stan have determined, if we could build components that operate outside this thermal equilibrium, laptops wouldn't get so hot. And as a bonus, performance would increase and battery life extended by using power dissipated by other functions. Of course first, the researchers have to solve Maxwell's Demon, a theoretical concept that suggests that the energy flow from hot to cold could be disrupted if there were a way to control the transfer of energy between two units. Maxwell's Demon would let one component take the heat while another worked at a lower temperature.

Another concept they're examining is Brownian ratchets, which suggests that devices could be designed to convert non-equilibrium electrical activity into directed motion, allowing energy to be harvested from a heat source.

"These theories have been looked at from a physics perspective for years, but not from the perspective of electrical engineering," says Stan. "So that's where we are trying to break some ground."

And if Ghosh and Stan are successful, I can already hear the crowd at Henry's: "My laptop runs so cool that I don't need air conditioning" or "So what? My laptop runs so cool...."

-- Jonathan Erickson
jerickson@ddj.com

Posted by Jon Erickson at 03:34 PM  Permalink