Experimental investigation on stability and thermal conductivity of diathermic oil based TiO2 nanofluids

The rapid development of nanotechnology has opened up a new path for conventional heat transfer fluids to fabricate nanofluids, which could increase the efficiency of thermal systems remarkably. This paper studied TiO2 nanoparticles dispersed in diathermic oil to form nanofluids. In order to explore stability and transfer performance of TiO2 nanofluids, the two-step method was introduced to prepare the nanofluids with volume fraction up to 1.0 vol%. The sedimentation experiment was conducted. There was not obviously sedimentation or stratification by Zeta potential (ζ) and size analysis. The TiO2 nanofluids can be seen as stable systems. In addition, the thermal conductivity of each solution was measured under the same conditions, and the results showed that the thermal conductivity of nanofluids increased with increasing volume fractions of TiO2 nanoparticles and increasing of temperature. Thermal conductivity enhancement ratio was a linear relationship with the volume fractions. Adding TiO2 nanoparticles to base fluids was helpful to enhance heat transfer heat system.