Correlated slug velocity

Stewart and Davidson (38) correlated slug velocity data (for axisymmetric slugs) with the following expression ... 

In the same way, Xu et al. (2013) proposed a correlation (Eq. 2.2.3) that includes the effects of slug velocity Uuc, capillary diameter d, and aqueous to organic phase flow rate ratio q. The capillary diameters for the correlation were 0.6 and 0.8 mm. 

This map has been checked by many researchers, indicating that it is applicable to a wide range of conditions. Also shown in Figure 3.4 are correlations derived by Mishima and Ishii (1984), which used similar basic principles except for the slug-to-churn transition. These authors pointed out that, in view of the practical applications of the separate-fluid model to transient analysis, flow regime criteria based on the superficial velocities of the liquid and gas may not be consistent with the separate-flow model formulation. A direct geometric parameter such as the... 

Fig. 9.10 General correlation for the rise velocity of slug flow bubbles (W2).

Narayanan et al.88 correlated gas holdup to the superficial gas velocity empirically and found hG oc U0G for U0G < 6.7 cm s 1 and hG oc UoG 8 for 6.7 cm s-1 < Uoc < 21.34 cm s"1. Hovmand and Davidson43 proposed a slug-flow model to correlate the gas holdup in gas-liquid-solid fluidized beds at superficial gas velocities in excess of that required for the incipient fluidization of solids. They correlated the gas holdup and superficial gas velocity by the equation... 

It was supposed, that for a high vapor velocity and a thin liquid film the influence of gravity is small and the correlation for up flow was used. Total boiling suppression occurs when mass quality more than 0.3 for a film thickness less than 60 pm. That value is close to the bubble departure diameter observed for flow boiling in a film. When the film thickness is smaller than the critical one, the forced convection occurs with a small heat transfer coefficient. The crisis of the heat transfer was observed for a complete liquid evaporation on a heated wall. While the mass quality less than 0.3, we have the cell or slug flow mode, so boiling is not suppressed. 

If the sintered plate is used for aeration kj a shows a pronounced maximum at low uq (homogeneous flow). At higher gas velocities (uq>2-3 cm/s) in the slug flow regime kLa becomes independent of the sparger type and can be correlated by ... 

Bercic and Pintar [40] measured gas-liquid mass transfer in a single channel for a wide range of superficial gas and liquid velocities (Figure 11.4). Their experimental set-up allowed the independent variation of bubble and slug length, but most of their experiments were performed under conditions where > tp. They correlated their data for a methane-water system as... 

This theoretical expression for the velocity of square-nosed gas slugs has been shown to be in reasonable agreement with available experimental measurements (Gibilaro et al., 1998). It is of similar form to published correlations (Hovmand and Davidson, 1971) for round-nosed axisym-metic and asymmetric gas slugs, both of which travel much faster relative to the solid slug ... 

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