Buoyancy Driven Heat Transfer Behavior of Zinc Oxide (ZnO)–Water Nanofluids Available to Purchase

The systematic experiments were performed for buoyancy driven heat transfer of zinc oxide (ZnO)-water nanofluids with volume fraction 0.5%, 1%, and 2% in rectangular (50×50×75mm) cavity heated from below. In addition to determining the convective heat transfer coefficients, this study also included experimental determination of density, effective thermal conductivity, and rheological behavior of nanofluids. For all the properties and natural convection behavior De-Ionized (DI) water was used as the baseline data. The results show that density measurements agree well with predicted values by equation, thermal conductivity enhanced by ∼14% for 2 vol% nanofluids, and shear thinning behavior of nanofluids. The natural convection behavior shows degradation of heat transfer and degradation increases with the volume fraction of nanoparticles. Probable reasons of degradation are discussed in the paper.