Experimental investigation of heat transport in inhomogeneous bubbly flow

Biljana Gvozdić (1) , On-Yu Dung (1) , Elise Alméras (1, 2) , Dennis P.M. van Gils (1) , Detlef Lohse (1) , Sander G. Huisman (1) , Chao Sun (1, 3)

1 University of Twente
2 LGC - Laboratoire de Génie Chimique
3 THU - Tsinghua University [Beijing]

In this work we study the heat transport in inhomogeneous bubbly flow. The experiments were performed in a rectangular bubble column heated from one side wall and cooled from the other, with millimetric bubbles introduced through one half of the injection section (close to the hot wall or close to the cold wall). We characterise the global heat transport while varying two parameters: the gas volume fraction , and the Rayleigh number . As captured by imaging and characterised using Laser Doppler Anemometry (LDA), different flow regimes occur with increasing gas flow rates. In the generated inhomogeneous bubbly flow there are three main contributions to the mixing: (i) transport by the buoyancy driven recirculation, (ii) bubble induced turbulence (BIT) and (iii) shear-induced turbulence (SIT). The strength of these contributions and their interplay depends on the gas volume fraction which is reflected in the measured heat transport enhancement. We compare our results with the findings for heat transport in homogeneous bubbly flow from Gvozdić et al. (2018). We find that for the lower gas volume fractions (), inhomogeneous bubbly injection results in better heat transport due to induced large-scale circulation. In contrast, for , when the contribution of SIT becomes stronger, but so does the competition between all three contributions, the homogeneous injection is more efficient.

Mots clés: Bubbly flows; Heat transfer; Bubble column; Experiments

Domaines: Génie chimique; Génie des procédés

Biljana Gvozdić, On-Yu Dung, Elise Alméras, Dennis P.M. van Gils, Detlef Lohse, et al.. Experimental investigation of heat transport in inhomogeneous bubbly flow. Chemical Engineering Science, 2019, 198, pp.260-267. ⟨10.1016/j.ces.2018.09.040⟩. ⟨hal-02139238⟩