Bubble coalescence in a range of fluids: surface and viscous effects

Tse, Kathryn (2000). Bubble coalescence in a range of fluids: surface and viscous effects. University of Birmingham. Ph.D.

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Abstract

An in-depth investigation has been carried out into the use of a coalescence cell as a predictive tool for determining the coalescence behaviour in larger scale process apparatus. Within the cell, conditions can be manipulated to allow separate examination of the influences of system and operating parameters. The study has demonstrated that a much broader range of coalescence behaviour can be observed in the cell, beyond the step change commonly reported in the literature, by altering the range and combination of operating parameters (such as gas flow rate and nozzle separation distance). Coalescence behaviour was investigated in a range of well-defined fluids of differing viscosities, including several pure liquids (water, propan-1-ol and silicone fluid), solutions of various electrolyte (Na2SO4, MgSO4, KI, HNO3), \(n\)-alcohol (propan-1-ol) and non-polar solute (glycerol, sucrose, PPG) species and additionally, for a range of gas types (air, nitrogen, hydrogen and xenon). In all systems, coalescence behaviour was observed to be heavily dependent on operating parameters such as the contact pressure and temperature, which could moderate the influences of the gas-liquid system itself. To enable comparisons with the results obtained in the cell, the coalescence behaviour in laboratory-scale bubble columns was assessed. Observations were made of a previously unreported coalescence dependent break-up mechanism. Responses observed in the coalescence cell were seen to approach trends observed in the small-scale systems, despite being attributed to very different influences. As a general diagnostic tool, use of the cell is disadvantaged by the degree of rigour which must be applied to both experiments and the subsequent interpretation of results; however, as an analytical tool for investigating the coalescence process, the cell shows potential for advancing the current state of knowledge.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):