Chemical and Biomolecular Engineering - Theses

Permanent URI for this collection

Search Results

Now showing 1 - 10 of 21
  • Item
  • Item
    Thumbnail Image
    An investigation of the compression moulding and extrusion of polyethylene foam
    Buczma, Eugene ( 1979)
    The processes of compression moulding and extrusion of polyethylene foam using chemical blowing agents were investigated. Both high and low density polyethylenes together with the chemical blowing agents azodicarbonamide, Porofor S-44, 4,4'-oxybis(benzenesulphonyl hydrazide) and N,N'-dinitrosopentamethylenetetramine were used. The same mechanisms were found to be operative in both processes. The nucleation of cells was related to the decomposition of the chemical blowing agent used. Secondary nucleation of the diffusing gas was effected by the use of a very fine particle size silica. The processes of gas diffusion and gas dissolution in the melt were shown to be important in explaining the cell structure obtained. These were related to gas sorption studies. Very fine cellular structures could be obtained by compression moulding by using fast heating and cooling cycles. This reduced diffusion resulting in low foam density and fine cell size. The dielectric constant of the foam was related to foam density by the use of mixture formulae. Tensile properties were found to be dependent on cell size and, foam density.
  • Item
    Thumbnail Image
    Swirling flow of viscoelastic fluids
    Stokes, Jason R. ( 1998-10)
    The ability to understand and predict the flow behaviour of non-Newtonian fluids in swirling flow is industrially important for the efficient design and performance of processes which utilise fluids with complex rheological properties. In particular, fluids with elastic properties are not well described by non-Newtonian constitutive models, such that predictions using such models must be carefully validated. A benchmark problem is proposed here which provides a well defined geometry to study the swirling flow of non-Newtonian fluids as a test case for the validation of constitutive models. The confined swirling flow utilised is a torsionally driven cavity where the test fluid is confined in a cylinder with a rotating bottom lid, and stationary side walls and top lid. The flow field is three-dimensional and consists of both a primary motion, which is directed azimuthally, and a secondary motion, which is located in the radial and axial plane of the cylinder and driven by inertial and/or elastic forces.
  • Item
    Thumbnail Image
    The melting point and viscosity of nickel smelter slags
    Ducret, Andrew Charles ( 1995-02)
    Western Mining Corporation produces nickel matte at the Kalgoorlie Nickel Smelter(KNS)from nickel sulphide concentrates within an integrated flash smelter.
  • Item
    Thumbnail Image
    Modelling of fluid flow and heat transfer of decaying swirl in a heated annulus
    Solnordal, Christopher Baard ( 1992-07)
    The fluid flow and heat transfer characteristics of the turbulent swirling flow of air through a heated annulus have been quantified. The motivation for this study was to improve the understanding of flow within a SIROSMELT top submerged industrial smelting lance. Within the lance, helical vane swirler flights are used to impart swirl to a coolant, so that heat transfer from the lance wall to the coolant is enhanced. A review of the literature revealed no information on the mean and turbulent flow structure for swirling flows in a heated annulus. (For complete abstract open document)
  • Item
    Thumbnail Image
    Characterisation of suspensions in settling and compression
    Green, Matthew Daryl ( 1997-06)
    The concentration of fine particle suspensions is a crucial step in many industrial processes, two major processes that depend on this are the disposal of mine tailings as highly concentrated slurries, and the wet casting of ceramic components from highly concentrated suspensions. The thickening and filtration operations in these processes are still not completely understood. The successful design and operation consolidation equipment must be based on the properties of the target suspension. The quantitative characterisation of suspensions in settling and compression was the prime objective of this thesis. In a general consolidation model, the behaviour of suspensions in settling and con1pression is fully defined by two parameters; the compressive yield stress function and the hindered settling function. The compressive yield stress quantifies the strength of the suspension network in compression and determines the maximum concentration achievable for any given applied force. The hindered settling function quantifies the hydrodynamic drag forces experienced by consolidating particles in the suspension and determines the settling velocity and the time scale for the consolidation process. These suspension consolidation parameters were determined using a variety of techniques. For measurement of the compressive yield stress, two centrifuge based techniques and a pressure filtration technique were evaluated both independently and with each other - with good results. It was thus verified that the compressive yield stress is a material property of suspensions in compression. For measurement of the hindered settling function, two pressure filtration techniques were developed using a custom built apparatus. Measurements were successfully made using these techniques for the first time. The materials used in the study were three aqueous metal oxide suspensions systems; Zr02, Ti02 and A120 3. The shear and compression rheology of these systems is fully controlled by manipulation of the particle surface chemistry which changes the suspension micro-structure. The validity of the general consolidation model was systematically studied using suspensions prepared under various conditions. Factors studied were the effects of flocculation state, initial concentration, steric stabilisation, suspension preparation methods and prior shear and compression history. These factors affected the compression rheology to varying degrees and were quantified. The conditions for maximum consolidation were determined. A correlation between shear and compression rheology also generated a useful empirical relationship that can be used in design and operation of consolidation equipment. Finally, the measurement of the compressive yield stress and hindered settling function of a suspension was applied to the prediction of the concentration profile and sediment height in an operating continuous thickener. With some refinement, the model and techniques used in this study are a viable means for design and optimisation of continuous thickeners based on the material properties of the suspension.
  • Item
    Thumbnail Image
    Aqueous-phase oxidation of brown-coal dewatering effluent using phenol as a model
    Devlin, Howard Royce ( 1982)
    Victorian-brown-coal dewatering effluent has been shown to contain quantities of phenol which would prevent its direct discharge to any water course. A proposal to oxidize this effluent, using oxygen, to less toxic compounds or more readily biodegradable material, has been investigated. A rapid-mixing stopped-flow apparatus, capable of examining the reaction between dissolved oxygen and aqueous phenol solutions under conditions of elevated temperature and pressure, has been designed and constructed. The phenol/oxygen reaction has been investigated at temperatures between 150°C and 225°C and under conditions of excess oxygen, excess phenol and near the stoichiometric ratio. An analytical system comprising a High-Performance Liquid Chromatograph has been developed and some reaction products not previously isolated from the phenol/oxygen reaction system have been identified. The experimental results have led to the development of a reaction pathway for phenol oxidation by oxygen. Reaction steps in the mechanism which are critical in determining the reaction product distributions and those that can be considered as rate limiting have been determined. The reaction pathway for oxidation of phenol by oxygen and published information for oxidation of phenol by ozone are used to develop a reaction pathway for ozone oxidation. The phenol/oxygen pathway is also used to propose several strategies for the operation of a brown-coal dewatering effluent treatment plant.
  • Item
    Thumbnail Image
    The sorption of ammonia on brown coal
    Oussa, Awad Rizk ( 1978)
    This thesis is a report of an investigation carried out by the author between 1st April 1969 to 31st October 1973 on a full time basis and from 1st December 1975 to 31st July 1978 on a part time basis. The research project was conducted by the author in the Department of Chemical Engineering, University of Melbourne, and on the premises of Australian Char Pty. Ltd., Morwell. The project was based on the premise that useful information on the brown coal-ammonia system can be obtained from sorption isotherms. The author designed and assembled the apparatus with this in mind, and developed a method of obtaining a self-consistent and meaningful interpretation of the sorption isotherms. Thermodynamic data for the ammonia sorption process was derived and used to develop a preliminary model for the ammonia-brown coal system. No separate literature review has been presented in the thesis, though frequent reference to the literature has been made in the discussions in each chapter. Finally, the experimental details have been included in the appendices at the end of the thesis.
  • Item
    Thumbnail Image
    Splashing due to gas injection
    Cullinan, Vincent John ( 1993)
    The splash event produced by a falling drop impinging on a bath of liquid was studied to enable a more fundamental understanding of the mechanisms of splash formation. An experimental method involving the use of a high speed photographic technique was developed to enable discrete splash events to be recorded at different time intervals. The effect of varying impact velocity, liquid viscosity and surface tension on the splash event was studied. The aspects of the splash mechanism that pertained to the projection of liquid above the liquid surface were monitored as a function of the experimental variables. Such aspects included the cavity depth, the Rayleigh jet behaviour and the extruded crown behaviour. Depending on the impact velocity of the falling drop, different shaped Rayleigh jets formed which varied in their manner of break up. Such changes in the Rayleigh jet behaviour could be related to the curvature of the interfacial cavity produced by the impact of the falling drop. As the impact velocity increased, the maximum height of the extruded crown increased. If the impact velocity exceeded a critical value, break up of the crown occurred. Increasing liquid viscosity had the effect of dissipating the energy of the system and hence producing less splash. Such viscous dissipating effects were quantified by the use of an energy balance. For liquids of a lower surface tension, there was evidence to suggest that a greater proportion of the incoming energy to the splash event was transferred to the extruded crown rather than to the cavity. Consequently, the splash produced from the break up and extrusion of the crown became more significant. A knowledge of the size of the bubbles reaching the liquid surface would assist in predicting the splashing behaviour of an industrial process which utilised gas injection.
  • Item
    Thumbnail Image
    The effect of return bends on the heat transfer from an internally flowing turbulent air stream in smooth tubes
    Batterham, Robin John ( 1968)
    The aim of the project was to investigate the effect of an 180° bend on the heat transfer from an internally flowing turbulent air stream. The presence of a bend was shown to increase the local heat transfer rate in the bend and in the upstream and downstream regions of the bend. (For complete summary open document)