| Title |
Local Heat Transfer Characteristics in Convective Partial Boiling by Impingement of Free-Surface/Submerged Circular Water Jets |
| Keywords |
Impinging jet ; 충돌제트 ; Nucleate boiling ; 핵비등 ; Free-surface jet ; 자유표면제트 ; Submerged jet ; 잠입제트 ; Local measurement ; 국소측정 |
| Abstract |
Single-phase convection and partial nucleate boiling in free-surface and submerged jet impingements of subcooled water ejected through a 2-mm-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 distributions of wall temperature and heat transfer coefficients were considered. Incipience of boiling began from far downstream in contrast with the cases of the planar water jets of high Reynolds numbers. Heat flux increase and velocity decrease 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 from1 to 12 had a significant effect on heat transfer around the stagnation point of the submerged jet, but not for the free-surface jet. The submerged jet provided the lower cooling performance than the free-surface jet due to the entrainment of the pool fluid of which temperature increased. |