Techniques for measuring the thermal conductivity of nanofluids: A review

There has been a rapid progress in research activities concerning nanofluids since a large enhancement in their thermal conductivity has been reported a decade ago. While this extraordinary thermal conductivity of nanofluids deserves scientific investigation, the inconsistency and controversy of the results reported by different groups for identical nanofluids across the world raises fundamental doubts and poses a hindrance in the potential applications of nanofluids. This paper presents a critical review of the several techniques for the measurement of thermal conductivity of nanofluids employed by the researchers. Additionally, a detailed description of a unique thermal conductivity measurement device based on the thermal comparator principle, developed by the present authors has been described. Besides the principle of this measurement device, the constructional details have been elaborated. Finally, some suggestions have been made for improving the reliability of the measurement of thermal conductivity.