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The most important application for thermoelectric materials is the energy conversion between heat and electricity. It is important to understand the heat transfer, drift electrical current and thermoelectric current in thermoelectric generators. The Seebeck effect is exploited to convert heat into electricity in thermoelectric generator. Assume that the p‐type and n‐type thermoelectric materials have the same ZT value, the thermoelectric conversion efficiency depends on the ZT value of the thermoelectric materials,

(1.32)

where η _c is the Carnot efficiency for the temperature difference at the hot (T _H) and cold ends (T _C),

(1.33)

and is the mean value of the operation temperatures,

(1.34)

Figure 1.18 Dependence of thermoelectric generation efficiency on the temperature and ZT value. The top thick line is the Carnot efficiency.

Source: Fanciulli et al. [31]. © Elsevier.

A higher ZT value gives rise to a higher conversion efficiency (Figure 1.18). But the thermoelectric conversion efficiency is always lower than the Carnot efficiency.