Prediction of bubble departure in forced convection boiling: A mechanistic model

Abstract

In the context of computational fluid dynamic simulations of boiling flows using time-averaged 13Eulerian multi-phase approaches, the many sub-models required to describe such a complex 14 phenomena are of particular importance. Of interest here, wall boiling requires calculation of the 15 contribution of evaporation to global heat transfer, which in turn relies on determination of the 16 active nucleation site density, bubble departure diameter and frequency of bubble departure.

Evaporation, boiling and explosive breakup of heterogeneous droplet in a high-temperature gas

“…At the same time, the special analysis of the processes of formation and growth of bubbles under the considered conditions is important. These processes are rather specific and represent a fascinating and independent scientific problem [47][48][49][50][51]. The solution of this problem will allow widening the concepts of the boiling regimes at inside interfaces and possible approaches to intensification of the boiling in heterogeneous droplets.…”

Prediction of Bubble Departure in Forced Convection Boiling with a Mechanistic Model That Considers Dynamic Contact Angle and Base Expansion

“…The latter defined a parameter b that considers the bubble sphericity during bubble growth [12]. Later, this parameter has been used by many other groups as a "calibration parameter" with values from 0.24 to 2.4 to fit the model to their experimental data [22]. Yun et al improved the model of Klausner et al by considering a bubble condensation and evaluating the model for a wider range of pressure, temperature, and flow rates for water as well [23].…”

“…In this equation, Pr is the Prandtl number of the liquid, C 2 is microlayer constant (determined as C 2 = 1.78 [22]) and f sub is the portion of the bubble surface in contact with the subcooled liquid. Re b is the bubble Reynolds number and T l is the liquid temperature distribution in the superheated layer.…”

“…Finally, it decreases back to zero due to bubble sliding, speed up and the decreased drag force resulting from the relative velocity between bubble and liquid. Since the dynamic contact and inclination angles are obtained from the model there is no need to predetermine them like the works done by Klausner et al [17], Hong et al [40], Colombo and Fairweather [22] and Raj et al [24]. In 2013, Krepper et al [1] assessed the application of Lemmert and Chawla correlations [41] (see Equation (60) to model the nucleation site density in a CFD simulation.…”

An Overall Bubble Diameter Model for the Flow Boiling and Numerical Analysis through Global Information Searching

“…For the critical situation of bubble departure, many correlations [12][13][14][15] have been presented by deriving the force equilibrium equation including the surface tension force, the drag force, the buoyancy force, the lift force, etc. Some modifications [16][17][18] have also been done considering the heat transfer effect through the Jacob number and the contact angle.…”