Automated thermal conductivity measurement algorithm for the transient hot wire method

Abstract

Even after more than 20 years of research, establishment of a nanofluid thermal conductivity enhancement mechanism is impeded by differences in research results among researchers. Thermal conductivity measurement results may differ considerably depending on the selection of the temperature history range used to estimate thermal conductivity. This range should be selected carefully considering factors such as the hot wire specifications and the applied heat, but comparisons between researchers’ choices have rarely been reported. To resolve this problem, herein we present an algorithm that estimates test fluid thermal conductivity based upon the inputs of various hot wire specifications, wire resistance history, and applied voltage. We confirm that the proposed algorithm gives more accurate and precise results comparing with the cases of selecting the range based on solely on the determination coefficient R2 and is effective in eliminating data affected by the errors. The proposed method for fluid thermal conductivity measurement is robust to differences in measurement conditions including operator skill level, applied voltage, and hot wire specifications. It is expected that the discrepancies noted across the results of different research groups would be greatly reduced by adopting the proposed method.