ICT2014 Abstracts

Conventional Thermoelectric Generators (TEG) used in applications such as exhaust heat recovery are typically limited in terms of power density due to their low efficiency. Additionally, they are generally costly due to the bulk use of rare earth elements such as Tellurium. If less material could be used for the same output, then the power density and the overall cost per kW of electricity produced could drop significantly.

In theory, the Seebeck effect is not directly dependent on the amount of thermoelectric (TE) material used, but only on the Seebeck coefficient and on the temperature differential across the hot and cold junctions of the modules. So the amount of material used should only affect the output insofar as it affects the temperature of the junctions. And in fact, the reduction of the module thickness increases the thermal conductance of the TE pairs. This will tend to reduce the temperature differential across the hot and cold junctions of the modules unless the total resistance of the thermal path up to the hot and cold junctions is kept to a minimum.

The present work assesses the effect of reducing the amount of thermoelectric (TE) material used (namely by reducing module thickness) on the electric output of conventional Bismuth Telluride thermoelectric generators. Commercial simulation packages such as ANSYS and bespoke programming have been used to model the thermoelectric generators to various degrees of detail. Effects such as component thickness variation, heat conduction, convection and radiation, thermal contact resistance, Joule effect and Peltier heat sinks and sources due to Seebeck-induced currents have been assessed.

It was found that indeed it is possible to reduce the use of bulk TE material while retaining a convenient output. However, effects such as thermal contact resistance were found to be increasingly important as active TE material thickness was decreased.