[16a-A34-1~8] Thermoelectric conversion in the present and future: How much can we increase ZT?

[16a-A34-5] Thermoelectric Properties for Cost Effective Generators – Theory and Challenges

〇Kazuaki Yazawa¹ (1.Purdue Univ.)

Keywords:thermoelectric

Toward a better thermoelectric figure-of-merit, i.e. higher ZT value, a reduction of thermal conductivity helps to minimize the mass use of such rare and expensive materials. It is because a fewer amount of material is required by reducing fill factor with remaining the internal thermal resistance of thermoelectric elements, at a thermodynamic maximum power output condition. The maximum power output happens at a condition of electro-thermal impedances match between internal and external. However, a smaller fill factor design also allows to increase the heat loss across the parasitic thermal bypass though a dielectric filler material or even still air. Hence, the relation of the thermal conductivities between the thermoelectric and dielectric materials becomes a challenge in addition to the lower limit of thermal conductivity by carrier contribution. ZT value strongly depends on temperature. Development of thermoelectric material must carefully consider if the temperature profile of the ZT value matches at the peak with an actual temperature range of application. The temperature range must consider the external temperature drops in the external thermal resistances.