International Journal of Thermophysics (2019) 40:59 https://doi.org/10.1007/s10765-019-2520-6 COMMENT Comments on “Can the Temperature Dependence of the Heat Transfer Coefficient of the Wire–Nanofluid Interface Explain the “Anomalous” Thermal Conductivity of Nanofluids Measured by the Hot-Wire Method?” Marc J. Assael 1 · William A. Wakeham 2 Received: 5 October 2018 / Accepted: 19 January 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract The paper seeks to answer a question posed in a recent paper by Hasselman [1] in this journal concerning the application of the transient hot-wire method to the measurement of the thermal conductivity of fluids in general, and the effective thermal conductivity of nanofluids, in particular. At the same time, the paper corrects a number of errors of fact and assertion made in that paper. Keywords Nanofluid · Thermal conductivity · Transient hot wire 1 Introduction Ever since Choi et al. [2] reported that measurements of the apparent thermal conduc- tivity of liquids containing small volume fractions of particles with a diameter of the order of nanometres appeared to show enhancements above the thermal conductivity of the base fluid that might reach as much as 300 % [3], there has been a substantial flurry of activity to repeat these observations and to exploit the observation in all sorts of systems and engineering applications [4–17]. Such a focus has been understandable because if it were really possible to increase the thermal conductivity of one mate- rial in an industrial heat exchange process by a factor of 3 without any detrimental effects; elsewhere, it would be a significant breakthrough. Heat exchange equipment could be made smaller, and there would be reductions in capital and recurrent costs of many processes. The feverish activity stimulated by this first observation led to a B Marc J. Assael assael@auth.gr 1 Department of Chemical Engineering, Aristotle University of Thessaloniki, 54636 Thessaloniki, Greece 2 Department of Chemical Engineering, Imperial College London, Prince Consort Road, London SW7 2BY, UK 0123456789().: V,-vol 123