Experimental study on heat transfer characteristics of dispersed flow during strong transient reflood process

Abstract

The dispersed heat transfer correlations obtained in the quasi-steady-state heating experiment may have some limitations in the strong transient reflood process. Therefore, this article will conduct a visualization experiment on single-rod channel reflood cooling under different working conditions. By combining the transient hydrodynamic characteristics of liquid droplets and the wall temperature transient curve, the boiling heat transfer characteristics of the dispersed flow stage during the reflood process are studied. Through comparative analysis, this article found that the traditional post-CHF (Critical Heat Flux) heat transfer correlations are difficult to characterize the impact of droplet number and size changes. This article is based on the form of a divided path heat transfer mechanism model. In response to the strong transient characteristics of dispersed flow during the reflood process in a restricted channel, the single-phase steam heat transfer model and the steam-droplet interfacial heat transfer model have been modified, greatly improving the prediction accuracy. The RMS of the predicted heat transfer coefficient decreased from 0.68 in the original model to 0.24 in the new model.