Coalescence and Disintegration of Bubbles in a Two Phase flow Through a Packed-Bed

ABSTRACT

A gas liquid two phase flow through a two-dimensional packed bed consisting of circular packing was studied using image processing technique under the bubbly flow regime. The dominant bubble breakup and coalescence mechanisms were identified using large number of image samples. Two dominant coalescence mechanisms identified are due to compression and deceleration associated with the bubbles and three dominant breakup mechanisms identified are due to liquid shear force, bubble acceleration and bubble impact. Data on various two-phase parameters, such as local void fraction, bubble velocity, size, number, and shape were obtained from the images. Results indicated that when a flow regime changed from bubbly to either trickling or pulsing flow, the number of average size bubbles significantly decreased and the shape of majority of bubbles was no longer spherical. The bubble coalescence and breakup mechanisms depend on local conditions such as local velocity of the bubble and pore geometry. The present bubble size distributions were compared with previous studies and the results on bubble size are in general agreement.

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