Exactly. TFA says "heat pump", but the imp on my shoulder says heat pumps don't scale down to palmtop size and it actually runs one of these, a thermoelectric

Exactly. TFA says "heat pump", but the imp on my shoulder says heat pumps don't scale down to palmtop size and it actually runs one of these, a thermoelectric cooler: https://lairdthermal.com/products/thermoelectric-cooler-modules https://lairdthermal.com/products/thermoelectric-cooler-modu... Efficiency is much lower than pumped-refrigerant systems. Access to a flow of cool ambient, external air will be critical.