Interface tracking based evaluation of bubble growth rates in high pressure pool boiling conditions

Component-scale modeling of boiling is predominantly based on the Eulerian-Eulerian two-fluid approach. Within this framework, wall boiling is accounted for via the RPI model, and within this model, the nucleating bubble is characterized using three main parameters: departure diameter (D), nucleation site density (N) and departure frequency (f). Typically, the magnitudes of these three parameters are obtained from empirical correlations. However, in recent years, efforts have been directed towards mechanistic modeling of the boiling process. Of the three parameters mentioned above, the departure diameter (D) is the least affected by the intrinsic uncertainties of the nucleate boiling process. This feature, along with its prominence within the RPI boiling model, has made it the primary candidate for mechanistic modeling ventures. Mechanistic modeling of D is mostly carried out through the solving of force balance equations on the bubble. The forces incorporated in these equations are formulated as functions of the radius of the bubble and have been developed for, and applied to, only low-pressure conditions. On the other hand, for high-pressure conditions, no mechanistic information is available regarding the growth rates of the bubbles and the forces acting on them. In this paper, we use a Direct Numerical Simulation (DNS) coupled with an interface tracking method to simulate bubble growth under high (up to 45 bar) pressure, to obtain the kind of mechanistic information required for an RPI-type approach, thus up-scaling DNS to large scale simulation based on a two-fluid approach. In this paper we will be comparing the resulting bubble growth rate curves with predictions made with existing experimental data.