Experimental investigation of natural convection heat transfer of SiO2/water nanofluid inside inclined enclosure

Natural convection heat transfer of SiO2/water nanofluids in a rectangular enclosure was investigated at different concentrations and inclination angles, experimentally. Results indicated that heat transfer has not significantly changed for low concentrations of nanofluids. However, at volume fraction of nanoparticles greater than 0.005, heat transfer coefficient decreased with concentration of nanofluid. The effect of tilt angle on heat transfer was also examined. It was found that at low concentrations of nanofluid, the effect of tilt angle on Nusselt number is more pronounced. Influence of concentration of nanofluid on Nusselt number decreases with increasing inclination angle of the cavity or approaching the heated wall to vertical state. The highest values of Nusselt number were obtained for tilt angles of 0 degrees or horizontal state, and heat transfer rate was decreased with inclination angle.