THERMOELECTRIC MICRO-SCALE GENERATION BY CARBONACEOUS DEVICES

The paper reports on research focused on the use of largely available carbonaceous materials,such as graphite, carbon black and chars, as thermoelectric materials for micro-generation athigh temperature. The key feature is the possibility to ignite the thermoelectric device toself-sustain electric generation. The results of the tests performed with such materials, under bothcold and hot conditions, showed that a significant change of the electromotive force, with absoluteincrease up to three orders of magnitude, occurred under hot conditions with flame irradiation,achieving measured values of electromotive force up to 55 mV, in the best case. Monoliths based onbiomass chars and covered with a layer of gunpowder gave rise to similar variation of the Seebeckcoefficient, as the case of the flame exposed samples. This result confirms the basic idea of the investigationand the possibility of generating an electrical peak in a self-sufficient combustionthermoelectric device with power up to 1.0 W. A theoretical assessment has been proposed to providean interpretation of the observed phenomenology, which is related to the non-linear dependenceof the material properties on temperature, in particular the Seebeck coefficient andthermal conductivity.