Experimental Evaluation of the Seebeck Coefficient of a Commercial Thermoelectric Generator under Vacuum Conditions

This study aims to evaluate the performance of a commercial thermoelectric generator (TEG) module for electrical generation under vacuum and low-temperature conditions approaching those relevant to space-related applications and certain thermal environments encountered in Low Earth Orbit (LEO).). The assessment requires the measurement of the effective Seebeck coefficient of the selected TEG under controlled temperature differences. Indeed, the hot-side temperature was increased (up to 140 °C) while the cold side was maintained at fixed conditions. The Seebeck coefficient was extracted from the linear relationship between open-circuit voltage and applied temperature difference. The results were compared with the manufacturer's reference value in the specified temperature range and the theoretical predictions derived from temperature-dependent Seebeck polynomials using an analytical formulation. The study was then extended to lower cold-side temperatures (down to -80 °C) to simulate a scenario nearer to a space application. Within the nominal temperature range, the experimental Seebeck coefficient agrees closely with the datasheet value and remains lower than the intrinsic material-level prediction.