STUDY ON BOILING HEAT TRANSFER AND CRITICAL HEAT FLUX IN MIST COOLING (EFFECT OF AIR FLOW RATE ON HEAT TRANSFER AND BEHAVIOR OF LIQUID ON HEATING SURFACE)

摘要

Boiling heat transfer and critical heat flux -CHF- in mist cooling were investigated experimentally. In particular, the heat transfer in the mist cooling for low droplet density was examined focusing on the effects of liquid and air flow rates and behaviors of droplets and a liquid film on the heat transfer characteristics. Steady heat transfer experiments of a copper block were conducted for mist flow of air and water in a range of air flow rate from 40 to 120 1_N/min. Water flow rate was 0.3, 1.8, 4.0 and 8.0 1/hr, respectively. Three correlations of the mist cooling rate for non-boiling, evaporation of droplets and evaporation of the liquid film were developed with microscopic parameters of two-phase flow, respectively. Furthermore, a CHF model based on maximum evaporation rate of actual liquid fraction on a heater was presented through comparison with the present experimental results.