Influence of mass transfer on bubble plume hydrodynamics

Abstract

This paper presents an integral model to evaluate the impact of gas transfer on the hydrodynamics of bubble plumes. The model is based on the Gaussian type self-similarity and functional relationships for the entrainment coeffi cient and factor of momentum amplifi cation due to turbulence. The impact of mass transfer on bubble plume hydrodynamics is investigated considering different bubble sizes, gas fl ow rates and water depths. The results revealed a relevant impact when fi ne bubbles are considered, even for moderate water depths. Additionally, model simulations indicate that for weak bubble plumes (i.e., with relatively low fl ow rates and large depths and slip velocities), both dissolution and turbulence can affect plume hydrodynamics, which demonstrates the importance of taking the momentum amplifi cation factor relationship into account. For deeper water conditions, simulations of bubble dissolution/decompression using the present model and classical models available in the literature resulted in a very good agreement for both aeration and oxygenation processes. Sensitivity analysis showed that the water depth, followed by the bubble size and the fl ow rate are the most important parameters that affect plume hydrodynamics. Lastly, dimensionless correlations are proposed to assess the impact of mass transfer on plume hydrodynamics, including both the aeration and oxygenation modes.

Circulation induced by diffused aeration in a shallow lake

“…This agrees well with the values of 6.6-8.1 mm estimated from the correlation given by Lima Neto (2015). For such bubble sizes and the above air flow rate/water depth conditions, the effect of gas-liquid mass transfer on bubble plume hydrodynamics is expected to be negligible (see Lima Neto and Parente, 2016). An electromagnetic propeller anemometer (Omni Instruments, MiniWater20) with an internal diameter of 22 mm was used to measure the mean horizontal water velocity u in the surface flow induced by the bubble plumes, as shown schematically in Fig.…”

“…Bubble plumes generated by diffused aeration are widely used for treating wastewater and ameliorating water quality problems in lakes and reservoirs (Bombardelli et al, 2007;Socolofsky et al, 2008;Lima Neto, 2012a,b;Lima Neto and Parente, 2016). In addition to supplementing the dissolved oxygen levels and reducing internal phosphorus loading in water bodies, bubble plumes also generate water circulation patterns that can prevent or destroy stratification (Wüest et al, 1992;Singleton et al, 2010;.…”

Spacing effect on pool boiling performance of three triangular pitched and vertically oriented tubes

“…It can also be seen, that the bubbles are creating a "flambeau"-like or "cone"-like shape plum along the tubes height that is turned by its apex to the base of the tubes bundle. Similar effect was previously reported and described for the bubbles released in the liquid pool [31,32,33]. Additionally, to the reported findings, while boiling, this effect has been also caused by the interaction between floating up bubbles and the bubbles on the stage of nucleation and departure.…”