Bubble bubbling regimes

Fig. 8. (a) Schematic for an FCC unit showing where the various fluidization regimes are found and (b) a corresponding phase diagram for Group A powder (FCC catalyst) where the numbers on the curves represent the superficial soHd velocity in m/s. A represents the bubbling regime B, the turbulent ... 

Single-Bubble Regime Bubbles are produced one at a time, their size being determined primarily by the orifice diameter d, the interfacial tension of the gasdiquid film C, the densities of the liquid Pl and gas Pc, and the gravitational acceleration g according to the relation... 

Even if the interfacial tension is measured accurately, there may be doubt about its applicability to the surface of bubbles being rapidly formed in a solution of a surface-active agent, for the bubble surface may not have time to become equihbrated with the solution. Coppock and Meiklejohn [Trans. Instn. Chem. Engrs., 29, 75 (1951)] reported that bubbles formed in the single-bubble regime at an orifice in a solution of a commercial detergent had a diameter larger than that calculated in terms of the measured surface tension of the solution [Eq. (14-206)]. The disparity is probably a reflection of unequihbrated bubble laminae. 

Smooth surface regime Rough-surface Breaking-wave regime (bubble) regime/... 

Fig. 2.32 Diabatic flow pattern map for vaporizing flow in uniformly heated micro-channel, R-134a, d = 0.5 mm, L = 70 mm, Tg = 30 °C, = 50 kW/m without subcooling at inlet. Flow patterns isolated bubble regime (IB), coalescing bubble regime (CB), annular (completely coalesced) regime (A), post-dryout regime (PD). Reprinted from Thome et al. (2006) with permission...

Zahradnik, J. and M. Fialova, The effect of bubbling regime on gas and liquid phase mixing in bubble column reactors. Chemical Engineering Science, 1996. 51(10) p. 2491-2500. 

Figure 9 compares Equation 20 with the recent pressure drop flow rate data of Friedmann, Chen, and Gauglitz (5) for a 1 wt% commercial sodium alkyl sulfonate dimer (Chaser SD-1000) stabilized foam in a Berea sandstone. These data are particularly useful because they have been corrected for foam blockage and therefore correctly reflect the flowing bubble regime. The solid line in Figure 9 is best fit according to Equation 20. Unfortunately, neither of the parameters c or 6 is available. Two sets of estimates are shown in Figure 9. When e - 0 (i.e., no surfactant effect) the bubble size is about 30% of a grain diameter. When — 0.1 mm (i.e., a value characteristic of those in Figure 8) the bubble size is about 10 grain diameters. We assert that Equation 20 not only predicts the correct velocity behavior of foam but it does so with reasonable parameter values (23).

Figure 9. Experimental data for the effective viscosity of the foam bubble regime in Berea sandstone as a function of the foam superficial velocity. The solid line is drawn according to the scaling theory with values of the two sets of parameters e and 6 listed.

Figure 31. Comparison of dynamic pressure variance for three properly scaled beds and two mis-scaled beds in bubbling regime (DiFelice, et al., 1992a). Properly scaled , laposorb A, sand O, bronze. Intentionally mis-scaled +, iron D, sand.

Fluidization Regime. As for traditional fluidization applications, the fluidization regime—dispersed bubble, coalesced bubble, or slugging—in which a three-phase fluidized bioreactor operates depends strongly on the system parameters and operating conditions. Generally, desirable fluidization is considered to be characterized by stable operation with uniform phase holdups, typical of the dispersed bubble regime. It would be useful to be able to predict what conditions will produce such behavior. 

Overall gas holdup increases with gas velocity in the dispersed bubble regime for both low and high density particle systems (Davison, 1989 Tang and Fan, 1989 Bly and Worden, 1990 Nore et al., 1992 Pottboff and Bohnet, 1993). As gas velocity increases and the system enters the coalesced and slugging regimes, the rate of increase in the overall gas holdup decreases (Bly and Worden, 1990). 

Beat wave, 169 Betatron emission, 178 Betatron radiation, 168 Bismuth (Bi), 48, 58, 59 Bond-softening, 7 Bragg crystals, 125 Bragg peak, 175 Bremsstrahlung, 139, 168, 173 Bremsstrahlung photons, 159 Brunei effect, 201 Bubble regime, 171 Bulk modifications, 82, 103... 

Thus, the bubble velocity is within the intermediate-bubble regime, and equation 23.3-6b is used for fb. Parameters u b, Kbe, fb, and Lj[ are calculated as follows ... 

Liger-Belair, G., Tufaile, A., Jeandet, P., and SartorelU, J.-C. (2006b). Champagne experiences various rhythmical bubbling regimes in a flute. /. Agric. Food. Chem. 54, 6989-6995. 

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