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The effect of liquid physical properties on gas-liquid ejector performance.

Miller, Julie H. (1997) The effect of liquid physical properties on gas-liquid ejector performance. Doctoral thesis, University of Surrey (United Kingdom)..

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This thesis extends previous work that has been carried out in an air-water system in a gas-liquid ejector. The thesis presents the experimental programme undertaken and contains a survey of the available literature on the effects of liquid physical properties in gas-liquid ejector systems. The survey concentrates on the effects of coalescence inhibition and touches on viscosity effects. Due to the lack of research in such systems, the literature review was extended to look at the work carried out in stagnant fluids and in other systems such as stirred tank reactors and bubble columns. This was used to identify a fluid that would represent a non-coalescing system. The experimental work was split into three parts: the effect a) of flow parameters on gas holdup and bubble size in an air-water system; b) of coalescence inhibition and c) of liquid viscosity on ejector performance. Parameters measured in order to establish the ejector performance in the coalescence inhibited and viscous solutions were gas entrainment, ejector pumping efficiency, bubble size, gas holdup and mass transfer. A non-coalescing fluid was simulated using a 0.08M Magnesium Sulphate solution. It is believed, based on results reported by various researchers that this concentration was sufficient to achieve a near non-coalescing fluid. Various experiments were carried out and the above mentioned parameters measured to assess the ejector performance against a pure water system. Experimental results showed that coalescence inhibition has little effect on gas entrainment or gas holdup (and hence slip-velocity). However, the Sauter mean diameter decreases with the non-coalescing nature and the bubbles were seen to be more spherical and appeared more rigid. Values of kLa are similar between coalescing and non-coalescing systems; this is due to an increase in a and at the same time a corresponding decrease in kL which may be due to a decrease in diffusivity. Newtonian CMC solution provided a viscous system over a range of viscosities (3 - 10 mPas). Comparisons were made with water (1 mPas) for the ejector performance parameters. Experimental results showed that viscosity has a small effect on gas entrainment and ejector pumping efficiency and little effect on gas holdup (and hence slip-velocity). Sauter mean diameter was found to decrease with an increase in liquid viscosity, producing more spherical bubbles. Values of kLa were smaller for an increase in viscosity, despite an increase in a. This is due to a more significant decrease in kL due to the effect of liquid viscosity reducing the diffusivity.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Miller, Julie H.
Date : 1997
Contributors :
Depositing User : EPrints Services
Date Deposited : 09 Nov 2017 12:13
Last Modified : 15 Mar 2018 23:03

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