Single-phase convection and partial nucleate boiling in free-surface and submerged jet impingements of subcooled water through a 2 ㎜-diameter circular pipe nozzle were investigated by local measurements. Effects of jet velocity and nozzle-to-impingi...
Single-phase convection and partial nucleate boiling in free-surface and submerged jet impingements of subcooled water through a 2 ㎜-diameter circular pipe nozzle were investigated by local measurements. Effects of jet velocity and nozzle-to-impinging surface distance as well as heat flux on nucleate boiling were considered. Heat flux increase reduced the temperature difference between stagnation and far-downstream regions with the increasing influence of boiling in partial boiling regime. The change in nozzle-to-impinging surface distance from H/d=1 to 12 had a significant effect on the stagnation heat transfer of the submerged jet, not the free-surface jet. The submerged jet provided a worse cooling performance due to the temperature increase of the pool, thereby being more sensitive to the elocity variation from 1 to 3.9 ㎧.