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Peltier devices are used for 12Vdc refrigerators(as those used in RVs) and also to cool dish mounted equipment as LNAs. Actually they are a kind of junction one side gets hot and the other gets cool. The heat is "pumped" from one side to the other. Several devices back to back can be used.
I have read that they are reversible, that is if you invert the supply the cool and hot sides exchange places.