EVALUATION OF THERMAL-CONDUCTIVITY FROM TEMPERATURE PROFILES

A new dynamic technique for the measurement of thermal conductivity is being developed at IMGC. The experiment consists in bringing the spec imen to high temperatures with a current pulse and in measuring the te mperature profiles during the free cooling period. Different technique s can be used to extract the information on thermal conductivity from the profiles. The numerical computation of thermal conductivity from t he experimental temperature profiles in absolute space is possible, bu t it is difficult and cumbersome because one must know and take into t he account the exact position of the infinitesimal elements of the spe cimen in different profiles. Computations in tube-space (a fictitious space where no thermal expansion occurs) are simpler and lead to less complex numerical computations. Complementary techniques to evaluate t hermal conductivity as a function of temperature or at constant temper ature are presented with a discussion of advantages and disadvantages of each method. Computer simulations have tested the precision of the complex software. Numerically generated temperature profiles from know n thermophysical properties have been obtained and thermal conductivit y has been recomputed from the profiles. The relative difference using different computational approaches and different fitting functions is always less than 0.1 %.