Ive been wondering about how small of a cooler you can build.
Although this probably is just really low-level engineering, i have a rather particular question.
For my idea, the cooler has to be as small as possible, rather efficient and not use a chemical compound or reaction that is not locally reversible. It has to be an fully working circle that, theoretically, keeps working, solely relying on electricity for power.
While I understand how certain cooling systems work, I could not find a satisfying example, since mobile phones, tablets and other handheld devices rely on, if any, air cooling.
However, what I'm searching for woul'd be a small cooler that can reach slightly lower temperatures than the surrounding area, lets say about 5 °C, maybe less or even more, if it just gets below average surrounding temperatures (room-temperatures).
Would this be achievable in a watch-like size? And how efficient woul'd that be, running on electrical reloading only?
EDIT: The heat would, as far as i understand thermodynamics, not be a big problem. A short-range "relocation" (idk the term) about a few centimeters to a small vent would be enough.