EXPERIMENTAL STUDY ON HEAT TRANSFER PERFORMANCE OF AL2O3-WATER NANOFLUID IN SPRAY COOLING SYSTEM
Spray cooling has the advantages of high heat transfer coefficient, small overheating, and so on, it is expected to become a new way of cooling high power electronic devices. The addition of solid nanoparticles in a fluid is one of the classical methods of heat transfer enhancement. But the research of nanofluid and spray cooling combined is still less. In this paper, the Al2O3-water nanofluid spray heat transfer performance in an open cycle spray cooling system is studied. The nanoparticles concentration are 0%, 0.02%, 0.05%, 0.1%, 0.5%, 1.0%, respectively. The experimental results show that the heat transfer effect of nanofluid is significantly stronger than that of water when the nanoparticles concentration is low (0.02%, 0.05%). But the strengthening effect is weakening with the increase of concentration, moreover, the heat transfer effect is even worse than water when the concentration is more than 0.1%. The main reason is nanoparticles are directly taken away by water when they impact to the heat surface and rebound back in water. As the weight percent increases, more and more nanoparticles deposited on the heat surface and format a nanoparticles layer, which will handicap the heat exchange between water and heat surface. And the thick of nanoparticles layer increases with the concentration rises, so the thermal resistance increases and finally resulting in heat transfer deterioration. Therefore, nanofluid can only strengthen the spray heat transfer performance under certain conditions.