Study on CHF characteristics in narrow rectangular channel under complex motion condition

Abstract

In present work, the critical heat flux (CHF) characteristics in narrow rectangular channel were theoretically investigated under complex motion condition. A three-field analysis program was developed combining with a unified form of additional forces caused by motions, and the program was validated by CHF experiment data with a better prediction accuracy. The CHF characteristics of rectangular channel were evaluated based on two types of situations: (1) oscillating inlet flow and (2) constant inlet flow with different motions including heaving, rolling and the coupled motion of heaving and rolling. The results show that the oscillation of the inlet flow has a great influence on the CHF, the increases in the amplitude and period of the inlet flow oscillation cause the dryout to occur in advance. When the inlet flow is fixed, various motion conditions have little effect on CHF for high mass flux, and the reduction of CHF does not exceed 5%. However, the CHF is obviously reduced for the low mass flux due to the significant oscillation or thinning effect of the outlet liquid film caused by motions.