Novel experimental data-driven bubble breakage model for universal application in Euler-Lagrange multiphase frameworks

Abstract

An experimental data driven model for the prediction of bubble breakage in gas–liquid multiphase reactors was developed which fulfills requirements of the Euler-Lagrangian (EL) framework for the analysis of individual bubbles. The critical Weber number (Wecrit) serves as the breakage criterion in combination with the minimum time between two consecutive breakage events. Wecrit indicates when the hydrodynamic forces acting on an individual bubble surmount its surface tension. Once the threshold is passed a binary bubble breakup event occurs, which results in the formation of daughter bubbles assigned to an M−shaped daughter size distribution (DSD). Optimum Wecrit values were obtained by minimizing the difference between simulated and measured Sauter mean diameters d32. The latter were derived from bubble size distributions (BSDs) measurements that cover about 11 – 89 W m−3 power inputs. Using deionized water and a minimum timespan of 30 ms between two consecutive breakages Wecrit = 6.1 was determined. To extend the scope of the model, characteristic media compositions for so-called syngas fermentations with Clostridium ljungdahlii were investigated. To match surface tension and viscosity with those of fresh medium (FM) and late phase medium (LPM), two aqueous solutions containing sodium dodecyl sulfate (SDS) and glycerol were prepared. Notably, the breakage model managed to well predict the impact of altered fluid properties of FM and LPM without requiring further calibration. The sum of Sauter diameter deviation between simulations and experiments was only 0.21 and 0.40 mm for FM and LPM, respectively.