A study of the mechanism of solid-paricle enhanced nucleate boiling heat transfer at a flat heating surface

摘要

This paper presents the experimental and theoretical studies ont he effects of solid particles on pool boiling heat transfer at a flat heating surface. The results show that the heat transfer can be improved greatly with a proper amount of glass beads introduced into boiling water. It is revealed from the experimental results that the enhancement and the particle size are in inverse proportion. It is also well indicated that there exists a saturated initial bed depth of particles. Under the fully fluidized conditions the enhancement decreases with the heat flux applied. On the basis of the profound analysis of heat transfer augmentation mechanism the bubble departure diameter in particle beds, the minimum and the maximum heat fluxes for proper fluidization are derived. Finally a mechanicsvolume convection model is developed which both the positive and negative effects of solid particles on boiling are taken into consideration. Compared with the experimental observation and measurement results it is demonstrated that the model is qualitatively correct.