International Round Robin Test of Thermoelectric Generator Modules

Abstract

The status of metrology for the characterization of thermoelectric generator modules (TEM) is investigated in this work by an international round robin (RR) test including twelve laboratories from nine countries on three continents. Measurements have been performed with three samples of a Bi2Te3-based commercial TEM type, which has prevailed over three competing types during previous tests on the short- and long-term stability. A comparison of temperature-dependent results is provided up to 200 °C hot side temperature for the maximum power output Pmax, the incident heat flow Q˙In (at maximum efficiency conditions), and the maximum efficiency ηmax. Data evaluation from all RR participants reveals maximum standard deviations for these measurands of 27.2% (Pmax), 59.2% (Q˙In), and 25.9% (ηmax). A comparison between RR data sets and reference data from manufacturer specifications shows high deviations of up to 46%, too. These deviations reflect the absence of measurement guidelines and reference samples and confirm the need for improvements in the standardization of TEM metrology. Accordingly, the results of the RR are presented against the background of our own investigations on the uncertainty budgets for the determination of the abovementioned TEM properties using inhouse-developed characterization facilities, which comprise reference and absolute measurement techniques for the determination of heat flow.

Screening strategy for developing thermoelectric interface materials

“…We also prepared seven-pair modules with a leg length of ~3 mm because a shorter L means a higher output power density and lower module cost. Because an accurate measurement of heat flux ( 47 , 48 ) is challenging, conversion efficiency tests frequently involve large deviations. To address this, we conducted an international round-robin check of module efficiency testing with multiple laboratories in Asia, Europe, and the United States to verify our measurement reliability.…”

Efficiency Measurement and Modeling of a High‐Performance Mg2(Si,Sn)‐Based Thermoelectric Generator

“…The uncertainty of open‐circuit voltage was found to be 0.06% (for a measured value of 7.2 V) [ 53 ] (Supporting Information); the inner resistance had an uncertainty of 2.28% (for a measured value of 0.74 Ω) [ 53 ] ; the heat flow had an uncertainty of 12% for a measured value of 100 W [ 52 ] ; the power output had an uncertainty of 1.25% for a measured value of 2.5 W and the efficiency an uncertainty of 15.7% for a measured value of 4%. [ 55 ] Besides the choice of TE materials and contacting schemes, these deviations relate to the number of installed TE legs, their geometries, and the filling factor. Therefore, comparability to our TEG prototype is limited.…”

Roadmap on thermoelectricity

“…Device testing is also crucial to assess performance and reliability of TEG. Despite improvements for low temperature range [148], to the best of our knowledge no round-robin or assessed test procedure have been developed for intermediate temperature test. Even the maximum power point tracking and operating conditions of cascade modules have been barely explored.…”