Thermal conductivity and viscosity of water based nanodiamond (ND) nanofluids: An experimental study

Nanodiamond-water nanofluids were prepared and estimated the thermal conductivity, viscosity and also estimated their potential use in heat transfer applications. The purchased ultradispersed diamond (UDD) nanoparticles were treated with strong acid solution to make it into almost single nano-diamond (ND) particles. The acid treated ND particles were characterized by XRD, TEM, FTIR and XPS. The thermal conductivity and viscosity of ND nanofluids were investigated experimentally, whereas the density and specific heat were estimated theoretically. At 1.0 vol%, the thermal conductivity enhancements of 12.7% and 22.8%, at 1.0 vol%, the viscosity enhancements of 1.57-times and 1.8-times were observed at temperatures of 293 K and 333 K compared to water data. The theoretical models of Maxwell and Einstein have failed to estimate the thermal conductivity and viscosity of nanofluids as a function of temperature. New thermal conductivity and viscosity correlations were proposed by including the effects of volume concentrations and temperatures. Prasher et al. model and the Mouromtseff number were used to study the heat transfer capability of ND nanofluid under laminar and turbulent flow conditions.