Measurement of the thermal conductivity of nanofluids by the multicurrent hot-wire method

We present experimental results of the thermal conductivity of several nanofluids prepared by dispersing nanoparticles of SiO2 and CuO in water and ethylene glycol at various concentrations up to ≈5% in mass fraction. The measurements have been performed by the multicurrent hot-wire technique. Good agreement, within 2%, is found in recommended and published thermal conductivities of the pure fluids. Our experimental technique allows a very accurate determination of the enhancement in the thermal conductivity of the fluids due to the presence of dispersed nanoparticles. Measured enhancements compare well with some of the values published so far in the literature. We have compared our results with simple theoretical models that predict the thermal conductivity of solid suspensions and found that in some cases observed enhancements are several times larger than the predicted ones.