BOILING HEAT TRANSFER PERFORMANCE OF A BRASS BEADS-PACKED POROUS LAYER SUBJECTED TO SUBMERGED JET IMPINGEMENT

Submerged impingement boiling has been extensively applied in industrial cooling owing to its high heat transfer coefficient (HTC). A particles-packed porous layer with enlarged heat transfer area and special internal porous structure can improve the fluid disturbance and produce adequate bubble nucleation sites. An experimental investigation on submerged jet impinging boiling of a brass beads-packed porous layer was conducted. The effects of jet flow rate, fluid inlet subcooling, beads diameter, layer number as well as various double layer combination models on heat transfer performance were analyzed. The impact on the onset of nucleate boiling (ONB) and critical heat flux (CHF) was also explored. lire results show that better cooling property can be obtained for a higher jet flow rate, a higher fluid inlet subcooling, and a smaller single layer bead diameter, while the optimal layer number and double layer combination model exist for best heat transfer. Besides, a high-speed camera was utilized to capture the actual scene of submerged jet impingement boiling for visualization study of the dynamics evolution of vapor bubbles which would be highly linked to the heat transfer process.