Challenges of Transient-Plane-Source Measurements at Temperatures Between 500K and 1000K

Abstract

In this study, the e ective thermal conductivity of a variety of materials is deter- mined using a TPS based HotDisk Analyzer. The performance of this method is illustrated by application of three di erent materials viz. SILCAL 1100, OM100 and 1.4841 (X15CrNiSi25-21), with SILCAL 1100 serving as a reference case, as it is well documented in the literature. Numerous experiments were conducted for SILCAL 1100 by means of the e ective thermal conductivity (ETC), and deviations were found to increase up to 35% compared to Ebert et al. [1]. An intensive analysis of the TPS system reveals two possible sources of de- viation of the ETC. The TPS measurement may be a ected by an initially steady-state non-homogeneous temperature eld, but the deviations may also be a consequence of inappropriate temperature coecient of resistance (TCR) settings. Thus, the present work addresses the problem in three steps: rstly, the in uence of an initially steady-state, non-homogeneous temperature eld is evaluated numerically by comparing mean temperature rises of the sensor. Therefore, various example scenarios, which include variations of temperature gradients and uni-axial material properties are simulated. Secondly, the TCR values are determined experimentally by a number of experiments to rule out a variety of possible in uencing parameters such as insulating material of the sensor and connection cables. Thirdly, the TPS measurements are recalculated using the revised TCR data. The obtained ETC is compared to those ones ob- tained by comparative measurements. The numerical calculations indicate that non-homogeneous temperature elds do not a ect the recorded mean tempera- ture rise of the sensor, and thus the thermophysical properties associated with it. On the contrary, the experimental part supposes that calibrating the TCR values seems almost mandatory for achieving trustworthy data by the use of a TPS system.