Novel techniques for measurement of thermal conductivity of both highly and lowly conducting solid media

摘要

Two novel methods for the measurement of the thermal conductivity of solids are described. One of the methods serves for high-conductivity media (all metals), while the second is appropriate for media of low conductivity (as low as that of air). Both of these methods are distinguished by the unique simplicity of their constituents, the low cost of the measurement apparatus, the easy-to-use operational protocol, and the inherent control of the level of accuracy. The method used for the measurement of high conductivity values is based on a quasi-steady model. Its experimental implementation demonstrated excellent agreement with literature values and indicated that insulation was not necessary to achieve high accuracy. In an enhanced form, it could be applied over a very wide range of temperatures. For low-conductivity media, in contrast to common practice, the experimental approach did not involve guard heating. Syner-gistic numerical simulation provided the conditions for optimal use of the measurement device. In particular, the accuracy of the measured conductivity values could be predicted without approximation, and guidance was provided for an experimental protocol according to which any desired accuracy could be obtained. Numerical simulation was also used to support the measurement technique for high-thermal-conductivity media. The synergistic use of experimentation and numerical simulation enabled highly accurate values for thermal conductivity to be obtained in the most simple, least costly, and easy-to-use device.