Effect of Temperature on Convective Heat Transfer Enhancement of Aluminium Oxide/Water Nanofluid in a Circular Tube: An Experimental Study

The current research empirically examines the effect of temperature on the enhancement of convective heat transfer of nanofluid in a circular tube at the laminar developing region. The outer surface of the tube was subjected to a constant heat flux, and samples of γ-Al2O3-water were synthesized and used as the working fluid. The thermal conductivity of the nanofluid samples was measured using the hot-wire method. The results indicate that temperature has a significant impact on the effective thermal conductivity of the nanofluid. As the working temperature increases, so does the thermal conductivity of the aluminium oxide/water nanofluid compared to the base fluid. The experimental study investigated the influence of working temperature on the enhancement of convective heat transfer of nanofluids at two distinct temperatures, 23 °C and 30 °C. The findings demonstrate that the increase in convective heat transfer of nanofluids is highly dependent on the working temperature. The enhancement of convective heat transfer of the nanofluid at 23 °C exceeded that of 30 °C. Therefore, the increase in working temperature reduces the significance of the observed convective enhancement. However, it was observed that the thermal conductivity of the γ-Al2O3–water nanofluid elevated as the operational temperature rose. The decrease in heat transfer enhancement due to an increase in working temperature is a critical issue in the application of nanofluids. This limitation reduces the capability of nanofluids to decrease the size of heat transfer devices.