Experimental study on the influence of the aspect ratio of square cavity on natural convection heat transfer with Al2O3/Water nanofluids

Cavity design is an important aspect in thermal systems, and proper cavity design saves plenty of energy as losses are minimised through better design. In this work, the influence that the Aspect Ratio (AR) of a rectangular cavity filled with nanofluids has on the natural convection process is studied experimentally. Three different cavities with the AR of 1, 2 and 4 are fabricated, and the heat transfer performance is studied using two different fluids namely de-ionised water and Al2O3/Water nanofluids. It is found that the AR of the cavity has a significant effect on the heat transfer coefficient and Nusselt number. More importantly, the optimum nanofluid concentration for maximum heat transfer varies with the AR of the cavity. It also found that the Rayleigh number has a strong effect on the Nusselt number as well as nanofluid buoyancy.