Development of an Optical Method to Measure the Thermal Conductivity of Transparent Nanofluids

A comparative technique to measure the thermal conductivity of nanofluids was developed using a Mach-Zehnder interferometer. The technique is based on one-dimensional heat transfer occurring through a layer of deionized water and a layer of nanofluid, separated by an aluminum barrier. The fluid layers were heated from above to produce thermal stratification and to minimize free convection. The temperature gradient at the surface of both fluid domains, where the heat transfer occurs by pure conduction, was measured optically. The model was designed and evaluated using computational fluid dynamics. An experimental model was fabricated, and preliminary experiments were conducted with a SiO2-water nanofluid. The results indicate that this comparative optical method is viable. However, the thin optical windows used in the current experiments made accurate measurements difficult, due to stress-induced bending of the optical windows. Recommendations for improvements in the model design are discussed.