Experimental Investigation of TiO2-water Nanofluids Thermal Conductivity Synthesized by Sol-gel Technique

Background: Nanofluids have huge applications in many areas wherever heat transfer is concerned. The most profits of nanofluids exhibit superior heat transfer characteristics and great energy saving. The nanofluid thermal conductivity depends on several factors like particle size, particle material type, particle volume fraction, particle shape, operating temperature, base fluid material and type of additives. Method: In the present study, Titanium dioxide (TiO2) nanoparticles were prepared by sol-gel technique. The synthesized TiO2 was characterized using Transmission electron microscopy (TEM) and X-ray powder diffraction (XRD). The nanofluids were prepared by dispersing TiO2 nanoparticles in distilled water base fluid. The thermal conductivity of nanofluids was measured using a modified transient hot-wire method and was measured at different nanofluids volume fractions (0.03%, 0.06%, 0.12%, 0.23%, 0.35% and 0.47%) and temperature ranges from 10°C to 90°C. Results: The results showed that the thermal conductivity increased with increasing the nanoparticle concentrations and temperature. The maximum enhancement of thermal conductivity is 37.35 % at a nanofluid temperature of 90°C and volume fraction of 0.47% while it is 24.11% at a nanofluid temperature of 20°C for the same volume fraction. Conclusion: The results show that the thermal conductivity of the nanofluid remarkably increases with increasing the volume fraction. The thermal conductivity enhancement ratio increases with increasing the nanofluid temperature.