Mass Transfer Characteristics of the Submerged Liquid Jet

Abstract

Mass transfer characteristics of a liquid jet in a liquid continuous phase have been studied using a captured jet technique. A vertical jet was formed at the centre of a glass sided square-section cell of 102mm x 102mm x 305mm which held the stationary continuous phase. The technique allowed the length of exposed jet interface to be varied between 5 to 90 millimeters by adjustment of the gap between the nozzle and the capture probe. The flow rate of the jet phase could be varied between the minimum jet forming velocity up to and beyond the jet disruption velocity. Four binary systems and two ternary systems were studied. Water was retained as the continuous phase throughout. The jet geometry was photographically recorded and a particle trace photographic technique was used to determine the interfacial velocity. These experimental data were generally in poor agreement with theoretical predictions. The total mass transfer was determined over a range of jet lengths and jet flow rates and in either direction. Experimental mass transfer data were compared with a number of predictions. For transfer out of a binary system jet the best agreement was for a numerical solution of the diffusion equation incorporating experimental values for the jet diameter and interfacial velocity. The penetration theory solution model incorporating either experimental or predicted velocity data showed agreement within 25%. Transfer into the jet for binary systems, and in either direction for ternary systems, was enhanced at high flow rates and at long jet lengths beyond any of the predictions. The mechanism for enhancement was proposed to be turbulence within the jet and capture reservoir and predictions based on molecular diffusion alone would be invalid in such circumstances. Interfacial contamination in one of the ternary systems was observed to cause major deviation of its mass transfer characteristics from any of the predictions.