Peltix

Meet Peltix, a little tile who turns electric current into cold on one face and heat on the other.

When current flows across the junction between two different conductors, heat is either absorbed or released there. Jean Peltier discovered this in 1834. The heat flow per second is proportional to the current, Q̇ = ΠI, where Π is the Peltier coefficient of the pair.

A Peltier module packs many small blocks of n-type and p-type semiconductor between two ceramic plates. All the cold junctions face one plate and all the hot junctions face the other. Reverse the current and the hot and cold sides swap.

With Π = 0.05 V, a current of 4 A pumps 0.2 W through each junction pair. A typical module has about 127 pairs and moves tens of watts, enough for a picnic cooler.

Peltier coolers have no moving parts or fluids, so they are quiet and reliable. They cool laser diodes, camera sensors, and some laboratory instruments that need a steady temperature.