Effect of different blister positions on void fraction distribution under subcooled boiling conditions in narrow rectangular channel

Abstract

Cladding blistering of plate fuel element is one of the common accidents in the operation of research reactor. At present, there was little research on coolant flow boiling under blister conditions. However, the void fraction distribution of coolant under boiling condition was closely related to CHF. To study the effect of a blister on the void fraction under subcooled boiling, a numerical method was used to simulate the blister phenomenon in the narrow rectangular channel. The Euler two fluid model was adopted in this study and the modified RPI model was used to simulate flow boiling. The calculation results showed that a blister on the heating surface could lead to a significant change in the void fraction distribution near the blister area. The distribution trend of the void fraction in the rear of the blister was different under different axial blister position conditions. In general, the closer the axial position of the blister was to the outlet of the channel and the closer the lateral position was to the narrow edge of the narrow rectangular channel, and the larger the peak value of the local void fraction was. The local maximum of the void fraction could rise to over 0.8, and heat transfer deterioration may occur in the blister area.