Bubbles configurations

Figure 9.7. Bubble configurations and gas flow patterns around a bubble in gas-solid fluidized beds (a) Fast bubble (clouded bubble) Ub > /mf/ mf (b) Slow bubble (cloudless bubble)...

Kbe can also be accounted for mechanically from its relationship with and Kce given in Eq. (12.77). Following the analysis of Davidson and Harrison (1963) for Kbc and that of Kunii and Levenspiel (1968) for Kce for bubbling fluidized beds based on the bubble configuration described in 9.4.2.1, a material balance on a single rising bubble gives... 

M 12] [P 11] A certain induction time was found for artificial bubble configurations in a micro chamber [23], This period was 10 wall motion cycles or 100 time steps. 

FIGURE 11.2 Cross sections through bubble configurations in foams, (a) Balance of forces where three flat films meet, (b) Change of configuration when a small bubble amidst four larger ones disappears. 

Bubble Configurations Affect Film Cooling Dynamics, PW, p. 39, Oct. 1982. 

Figure 8 Bubble configurations and flow patterns around a fast bubble and a slow bubble, (a) Fast bubble ((7b > V ), (b) slow...

Figure 2.2 Drop and bubble configurations for measurement of equilibrium, advancing and receding contact angles [6]. (a) Equilibrium sessile drop, (b) equilibrium pendant bubble, (c) advancing and receding drop, (d) advancing and receding bubble, (e) drop on tilted plate. L = liquid, V = vapour.

Figure 10 Instantaneous snapshots of the bubble configuration in a bubble column equipped with a varying number of wire meshes to cut bubbles in to smaller pieces. From left to right, there are 0,1,3,4,6,10 wire meshes. The positionsof the wire meshes are indicated by the dotted lines. No mass transfer or chemical reaction is taking place in this case. Figure reproduced from Jam et al (2015) with permission.

This CFX leads to problems. After the surface is covered with CFx,it is no longer wet by the electrolyte and the low-energy configuration shows the formation of lenticular (lens-shaped) bubbles as shown in Fig. 7. These bubbles cover perhaps 95% of the surface10 and greatly reduce anode contact with the electrolyte. 

The bubbles play the role of the gas phase. The role of the liquid is played by an emulsion phase that consists of solid particles and suspending gas in a configuration similar to that at incipient fluidization. The quasi-phases are in cocurrent flow, with mass transfer between the phases and with a solid-catalyzed reaction occurring only in the emulsion phase. The downward flow of solids that occurs near the walls is not explicitly considered in this simplified model. 

Another important challenge is to enhance the reliability of the design and scale up of multi-phase reactors, such as fluidized bed reactors and bubble-colunms. The design uncertainty caused by the complex flow in these reactors has often led to the choice of a reactor configuration that is more reliable but less efficient. An example is Mobil use a packed-bed reactor for the methanol to gasoline process in New Zealand, even though a... 

Figure 3.19 Configuration of bubble layer as affected by flow rate at high subcooling (Freon-118) (a) low-velocity boiling flow (b) high-velocity boiling flow. (From Tong et al., 1966b. Copyright 5 1966 by American Society of Mechanical Engineers, New York. Reprinted with permission.)...

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