EXPERIMENTAL INVESTIGATION OF CHF ENHANCEMENT USING NANOFLUIDS (Al2O3) IN SUBCOOLED POOL BOILING

Phase - change heat transfer is an important process used in many engineering thermal designs. Boiling is an important phase change phenomena as it is a common heat transfer process in many thermal systems. There are many applications/processes in which engi neers employ the advantages of boiling heat transfer, as they seek to improve heat transfer performance. Recent research efforts have experimentally shown that nanofluids can have significantly better heat transfer properties than those of the pure base fl uids, such as water. Stable nanofluid was prepared with alumina nanoparticles (30 - 50 nm in diameter) and deionized water. The nanoparticle behaviors near the liquid wedge of bubbles were observed by high - speed camera. The microscopic morphology of the nanoparticle deposition layer at the heated surface was characterized by SEM images. It seems that the deposition layers could modify the morphology, but it also delays the detachment of small bubbles from the heated surface. The effect of geometry and bul k temperature also studied. A comparative experiment indicates that critical heat flux improved with increase in nanoparticles concentration. In the same fashion, the secondary objective is to give effect surface roughness on CHF by adding different conce ntrations of aluminium oxide nanoparticles.