Thermo electric refrigerator • Principle: When electric current is applied across the junction of two dissimilar metals cooling is produced at one junction and heating is produced in another junction. • Seeback effect • Peltier effect • Thomson effect • Julien effect • Conduction effect
Cont… • When two junction of pair of dissimilar metals are maintained at different temperature emf is generated.
Cont… • Peltier effect: When direct current is passed through a pair of dissimilar metal there is heating at one junction and cooling at another junction. By varying the current it was found that heating and cooling rates for different sets of material are proportional to current.
Cont…. • Thomson effect: when current I is made to pass through a single conductor having a temperature gradient (dT/dX) there is heat transfer and it is prescribed by a relation