Continuous gas sparging inside urtrafiltration hollow fibres (with the feed
) has been shown to be effective in enhancing permeate flux by reducing par
ticle deposit on the membrane wall. The present study focuses on the hydrod
ynamic characterisation of gas-liquid two-phase flow inside glass capillari
es in order to understand the mechanisms involved in the process improvemen
t. In capillaries of inner diameter less than 4 x 10(-3) m, experiments sho
wed that the how consisted of a slug how: a succession of gas and liquid sl
ugs rising up the pipe. As very few data are available concerning this type
of flow, it was visualised inside the glass capillaries so that its charac
teristics could be observed. Gas slug velocity, which is different from the
mean velocity of the flow, was calculated and a linear relationship found
between the two velocities. Gas and liquid slug lengths and frequency were
determined and plotted Versus operating parameters such as gas and liquid s
uperficial velocities, capillary inner diameters and fluid properties. (C)
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