Single bubble rising velocity

Using the correlation of Mendelson (3.191), the single bubble rising velocity is calculated as 29 cm/s. 

Single Bubble Rise Velocity in Liquid-Solid Suspensions... 

A single bubble rises through a fluid bed at a velocity, proportional to the square root of its diameter, or more accurately, the diameter of a sphere of equivalent volume ... 

For a better understanding of the interactions between parameters, it is often helpful to calculate the effective bubble rise velocity from measurea valves of for example, the data of Mersmann (loc. cit.) indicated = 0.6 for = 0.05 iti/s, giving U, = 0.083 m/s, which agrees with the data reported in Fig. 14-43 for the rise velocity of bubble clouds. The rise velocity of single bubbles, for d - 2 mm, is about 0.3 m/s, for liquids with viscosities not too different from water. Using this value in Eq. (14-220) and comparing with Fig. 14-104, one finds that at low values of the rise velocity of the bubbles... 

The rise velocity, Uo, in general depends on the bubble size, or the bubble Reynolds number but as bubble size increases, as in two-phase upflow, Ua approaches an asymptotic value that is independent of Reynolds number. The following expressions have been accepted for a single bubble rising in an infinite medium, and for one rising in a swarm of surrounding bubbles, respectively (Duckler and Taitel, 1991b) ... 

The large bubble rise velocities calculated from equation 19 are shown in Table II and they are significantly higher than the rise velocities of single bubbles of the same diameter. 

The latter requires the calculation of the rise velocity due to the single bubble rise. Considering... 

Chiba and Kobayashi [21], Van Swaay and Zuiderweg [23] and de Vries et al. [24] found that Eq. 13.4-6, derived from single-bubble experiments, does not adequately describe the true bubble-rising velocity, probably because of interaction between the bubbles. The first authors therefore deriv empirical correlations for the bubble size. 

Bubble rise velocities Single bubble in a quiescent bed at Bubbles in a bubbling bed... 

In addition, the discussion of kL for single bubbles has indicated the importance of the bubble diameter which essentially influences the constitution of the gas-liquid interface and the mean bubble rise velocity. Initial bubble size dg generated from single-orifice spargers can be calculated from the empirical equation... 

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