Characterization of Thermoelectric Modules for Powering Autonomous Sensors

The characterization of three commercial thermoelectric modules, designed for cooling/heating applications, is presented in order to employ the devices for power conversion, i.e as thermoelectric generators (TEG). The thermoelectric theory is briefly described at first, also taking into account the relationship between effective temperature difference across the TEG junctions and temperature difference applied externally, when insulating ceramic plates have a finite thermal conductance. Performances of thermoelectric modules are evaluated in terms of open-circuit output voltage and output power density for different temperature gradients and load conditions. Measurement techniques and experimental data are reported, showing the possibility of use thermoelectric devices for waste heat recover. A TEG was then used to supply an autonomous system that interfaces with a temperature sensor and periodically transmits the measurement information via a radiofrequency (RF) link. Experimental data show that the system works correctly and sends the RF signal when temperature difference applied across TEG is high enough.