STUDY ON BOILING HEAT TRANSFER IN MIST COOLING (THE CHARACTERISTICS OF HEAT TRANSFER AND DROPLETS IN MIST DISPERSED FLOW)

摘要

Recently, the dry/semi-dry machining without machining oil is proposed for ecology. The establishment of high heat removable technology is required in the future machining. In this study, as a proposal of the high heat removable technology, the boiling heat transfer in mist dispersed flow was investigated. In particular, the heat transfer in water mist for low droplet density, focusing on the heat transfer characteristics and behaviors of liquid film and droplets on a heating surface was examined experimentally. Furthermore, the velocities of droplets, the diameters of those and air velocity were measured by using LDV, immersion method and a fine Pitot tube, respectively. The heat transfer mechanism in the mist cooling was classified into three regions based on heat transfer characteristics and behaviors of the droplets and liquid film: non-boiling, evaporation/augmentation with the droplets and evaporation of the liquid film. Three correlations for the regions were developed with the microscopic parameters of two-phase flow, respectively.