New approaches for highly accurate efficiency determination of thermoelectric generator modules

L. Rauscher1, H. T. Kaibe1, H. Ishimabushi1, S. Sano1, E. Müller2, D. Platzek2

1Komatsu Ltd., Technology Research Center, Research Division,

1200, Manda, Hiratsuka-shi, Kanagawa, 254-8567 Japan

2German Aerospace Center (DLR), Institute of Materials Research, 51170 Köln, Germany

Recent efforts at Komatsu Ltd. to accomplish high temperature thermoelectric power generators have been accompanied by efforts to provide accurate and trustworthy characterization of these generator modules. As a result of these efforts a measurement device is presented to measure directly the conversion efficiency and maximal output power as well as the module resistant and the average Z value of the modules.

For this the module is exposed to an application like temperature difference and heat flux and electrical output is measured. The main difficulty with this kind of measurement is to determine the accurate heat flow. As conventional setups use a spatial temperature difference in reference materials, the measurement becomes highly prone to inaccurate temperature determination and uncertainties in heat conductivity of the reference material.

To overcome these drawbacks a new approach has been realized using an active thermally shielded heater system. This technique, which was deduced from adiabatic calorimeters, provides the opportunity to derive the heat flux in the generator directly from the Joule heat released in the heater system. This is considered as a big progress regarding accuracy and reliability as only easy to measure parameters have to be determined.

Reference measurements and module characterizations are presented. Comparison with measurements of other groups has been carried out.