Life tests of skutterudite thermoelectric unicouple (MAR-03)

M. El-Genk#1, H. Saber1, Y. Momozaki1, J. Sakamoto2, T. Caillat2

1Institute for Space and Nuclear Power Studies and Dept. of Chemical and Nuclear Engineering

The University of New Mexico, Albuquerque, NM 87131

2Jet Propulsion Laboratory/Californian Institute of Technology

4800 Oak Grove Drive, MS 277-207, Pasadena, CA 91109,

Results of life tests of a skutterudite unicouple (MAR-03) comprised of CeFe3.5Co0.5Sb12 p-leg and CoSb3 n-leg are presented. The tests, performed in argon at 0.051-0.068 MPa to suppress the antimony (Sb) sublimation from the n- and p-legs near the hot shoe, lasted for 450 hours, of which 261 hours are at constant hot and cold junction temperatures of 973 K and 300 K, respectively. The measured open-circuit voltage, Voc, and peak electric power, Pe,peak, decreased linearly from 203.6 mV and 671 mWe to 183.9 mV and 502 mWe, respectively, after 261 hours of cumulative testing. Similarly, the peak efficiency, h peak, calculated based on the measured voltage-current (V-I) characteristics and assuming zero side heat losses, decreased linearly from 10.7% to 10.03%. The actual efficiency values could be ~ 20% -25% lower due to the side heat losses trough the fiberglass insulation in the tests. Ongoing tests of similar unicouple (JUN-03) confirmed the present results and showed that these parameters reach asymptotic values that change very little after 460-500 hours of testing at hot and cold junction temperatures of 973 K and 300 K, respectively. Post-tests examination of MAR-03 showed minimal losses of Sb from the n- and p-legs.