The design of reactors with a dispersed gas in a liquid phase, e.g., bubble columns, is often based on rather roughly estimated parameters. To obtain a better understanding of the influence and interaction of the fluid dynamics and the mass transfer in the presence of a chemical reaction of NO and Fe(EDTA) in the liquid phase, the complex system of a bubbly flow is here reduced to single-bubble investigations. For this purpose, mass transfer is investigated with and without chemical reaction to be able to differentiate between various influencing factors and determined enhancement caused by the chemical reaction. Two experimental setups are applied, namely, the first one with two moving cameras where the velocity is adapted to the rising velocity of the bubble, and the second one is a countercurrent-flow cell.

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The relationship of the molecular structure in monolayers of unsaturated 1-monoglycerides to three-dimensional states is discussed. Monolayers of cfs-monoglycerides were in the expanded state under all the conditions studied and extremely stable. The physical properties of the monolayers in this state resemble in certain respects the physical properties of three-dimensional liquids. An expanded monolayer of 1-monoelaidin was transformed under pressure to a condensed state with a limiting area of 24 Á.2 3. This area was in close agreement with the cross-sectional area calculated for a hypothetical liquid crystal from density and X-ray data. The correlation indicates that the orientation of the molecules in the condensed monolayer of 1-monoelaidin approximates the orientation in the anhydrous three-dimensional crystal.

The relationship of the molecular structure in monolayers of saturated 1-and 2-monoglycerides to three-dimensional states is discussed. Cross-sectional areas per molecule were calculated from density and X-ray data for the three-dimensional crystals and hypothetical liquid crystals. The areas for the latter were in agreement with the limiting areas obtained for the liquid condensed state of the monolayers. A correlation was found between the stabilities of the condensed monolayers and the stabilities of the three-dimensional crystals. The results indicate that the orientation of the molecules in the condensed monolayers approximates the orientation in the anhydrous three-dimensional crystals.

The bubble rise behavior in viscoelastic media is analyzed numerically with CFD. Three different constitutive models, Giesekus, linear and exponential Phan-Thien-Tanner, are used to evaluate three different biopolymer solutions. The terminal rise velocity over a range of bubble sizes is validated against experimental data. The local velocity fields are compared with respect to the shape and onset of the negative wake. Furthermore, the normal and shear components of the stress fields, transformed according to the local flow direction, are given. The simulations are performed with a volume of fluid solver in OpenFOAM.