Modeling and simulation of flow boiling heat transfer on a downward-facing heating wall in the presence of vapor slugs

Abstract

Abstract Nucleate boiling on downward facing heating walls such as those found in IVR-ERVC and core catcher systems of advanced LWRs is characterized by bubbles of markedly different scales (small bubbles and vapor slugs). The heat transfer governing mechanism of deformable vapor slugs is different from that of small spherical bubbles. Therefore, the two-fluid wall-boiling model developed based on the characteristic of small-scale nucleate bubbles might not be sufficient for prediction of wall boiling heat transfer on a downward facing heating surface. In this article, a hybrid wall-boiling model is formulated and implemented in the solution framework of the Eulerian-Eulerian model coupled with a large-scale interface model and adaptive interface sharpening scheme. This approach gives a realistic representation of the physical phenomena present in flow boiling on a downward facing heating wall, and the validation against experimental data showed similar performance to the two-fluid model in terms of the prediction of wall boiling heat transfer.