Normally I skip the Youtube ads for gimmicks like perpetual motion machines. Ended up listening to one when it interrupted a clip I was using as background noise while eating.
This one was a miniature air conditioner. The action is unquestionably interesting. Instead of compressing and expanding Freon in a closed set of pipes, it compresses the air in the room and lets it expand.
At first it made sense. I’m familiar with the chilly air from a tire valve or spray can, Boyle’s Law applied to the air itself. Hey, why not? Older industrial food cooling methods applied Boyle to the food itself.
Then I thought more carefully and realized the heat added during compression doesn’t have anywhere to go. It would exit into the same room you’re trying to cool, and inevitable inefficiency would make the exit heat more than the cooling effect. The device could work with a hose to a window, but then it would lose the main advantage of portability.
The tire valve or spray can works because the compression was done much earlier, so the heat from compression was gradually dissipated over a long period.
A Peltier-effect cooler might work in a very small space. Thermoelectric coolers are common for portable ice chests to keep drinks cool, and also for direct cooling of heat-generating computer chips. It would take too much power to cool a room this way.
Polistra's Mill 