声空化场强化沸腾传热机理

MECHANISM OF BOILING HEAT TRANSFER INTENSIFIED BY ACOUSTIC CAVITATION FIELD

The effects of several factors on boiling heat transfer around horizontal circular copper tube in an acoustic cavitation field were investigated experimentally, and the inherent mechanism of the influences of acoustic cavitation parameters, fluid subcooling and nanometer particles were discussed in terms of local wall temperature. The experimental results show that the influence of cavitation bubbles reduced with the decreasing of cavitation distance, fluid subcooling and nanometer particle concentration, yet enhanced with the increasing of cavitation intensity. Boiling heat transfer could be remarkably intensified by acoustic cavitation due to not only sufficient provision of nucleated vapor embryos to the tube surface, but also increasing boiling area and consequently effective dissipation of heat. The addition of nanometer particles in liquid could result in roughness variation of heater surface and active reduction of cavitation bubbles.