Fabrication and evaluation of Bi-Te/Pb-Te cascade-type thermoelectric module

A thermoelectric generation system that can directly convert heat energy into electrical power offers a great advantage for utilizing 500-600° C class waste energy. To improve the efficiency of energy conversion, a Bi-Te/Pb-Te cascade-type thermoelectric module was fabricated. A Pb-Te module was assembled using Ag-Cu-type brazing alloy with a melting point of 520°C, and a Bi-Te module using Pb-Sn-Ag solder with a melting point of 295°C. In the case of both the Pb-Te module and the Bi-Te module, the rate of electrical resistance between thermoelectric elements and module was about 80-85% in generating conditions. Moreover the cascade-type module was able to generate electrical power of about 0.7W in a temperature difference of 380°C.