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Dispersed bubbly flow plays an imperative role in the chemical, biochemical and food industries. In the present work, the physics of liquid and gas properties on motion of microbubble in various liquid media was enunciated. The size of microbubble and the distribution of microbubbles generated by the pressurised dissolution method in different liquid media is also examined. Experimental result shows that the terminal rise velocity of microbubble is significantly affected by liquid and gas properties. The stability of microbubble dispersion is analysed by the drainage mechanism. The stability of microbubble dispersions is also examined by using its electrical properties. Correlations are also developed to interpret the bubble size, half-life and drainage mechanism of microbubble. The present study may be useful for further understanding microbubble aided processes and developing them for industrial applications.

Microbubbles exhibit excellent gas-dissolution abilities owing to their larger gas–liquid interfacial areas and longer residence times compared to conventional larger bubbles. Hence, it is expected that microbubbles should increase the efficiency of gas–liquid contact devices for various applications in chemical and biochemical processes. In most of these applications, it is necessary to understand the hydrodynamics, such as the rheology, pressure drop, and friction factor, associated with microbubble flow in devices. This study investigates the hydrodynamic characteristics of the flow of a microbubble suspension in a surfactant solution through a pipe. A mechanistic model has been developed to analyze the interfacial stress of microbubble suspension flow in a pipe by considering bubble formation, drag at the interface, and loss of energy due to wettability. A correlation between the intensity factor of interfacial stress and the friction factor based on energy loss due to wettability has been developed. The functional form of the correlation appears to predict the hydrodynamics satisfactorily for the flow of a microbubble suspension in a pipe. The present study might be helpful in further understanding multiphase flow for industrial applications.

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