Accurate and simple measurement of power generation efficiency and figure of merit of thermoelectric modules based on optical heating and non-contact temperature detection methods.

Abstract

In this study, we propose an accurate, simple, and versatile measurement method for power generation efficiency and device figure of merit ZT of thermoelectric devices. Toward the energy harvesting applications of thermoelectric generators, the performance characterization under low heat inflow and temperature difference is crucial. However, when the conventional solid-state heat flow meter is used, the uncertainty of power generation performance increases as heat input decreases. We have solved these problems by using a laser for heat input, improving the simplicity and accuracy of power generation efficiency measurements, especially at low heat flow. The direct and non-contact measurement of the temperature difference by using a thermography allowed us to determine ZT as well as power generation efficiency. The obtained mean power generation efficiency and ZT values are consistent with the values obtained by the conventional method within the error range, thereby validating the reliability of the proposed method. The relative uncertainties of the efficiency and ZT were estimated to be less than 3% and 12% for our method, respectively, whereas those were 19% and 24% in situations where the temperature difference was less than 6 K for the conventional method.