Experimental and theoretical investigation of thermal conductivity of some water-based nanofluids

Modified transient plane source method has been applied for thermal conductivity measurements of three water-based nanofluids containing Al₂O₃, TiO₂, and graphene nanoparticles. Experiments were conducted at different temperatures and concentrations. The effects of sort of nanoparticles, concentration, and diameter of nanoparticles as well as temperature were studied by comparing the experimental results with the predictions of ten preceding models. The overall performances of these models were compared in terms of percent error. Percent errors were observed in the current study ranging from vicinity of zero up to nearly 110% that belonged to Bruggeman model in predicting the thermal conductivity ratio of graphene/water nanofluids. All ten models performed acceptably in calculating thermal conductivity ratio of Al₂O₃ nanofluids with the maximum percent error of 2.16%. Four correlations are proposed based on the experimental results of this work three of which are special to each nanofluid and the fourth one is overall. These models succeeded to predict the thermal conductivity ratio of the studied nanofluids with considerably lower percent errors which was maximum 5.19% observed in predicting the thermal conductivity ratio of graphene/water nanofluid.