Engineering

Publication Search Results

Now showing 1 - 10 of 53
  • (2008) Lundie, S; Kröger, T; Peters, G; Rowley, HV; Feitz, A
    Conference Paper
    In this article, Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) quantify the performance of variable and fixed speed centrifugal chillers using two refrigerants (HCFC 123 or HFC 134A) in commercial air-conditioning systems. Electricity demand during operation causes the highest environmental and economic burdens for all options. Detailed energy simulation shows that chillers operate most of the time in partial load, therefore energy-optimised variable-speed systems are preferable. We demonstrate the significance of understanding each phase of the life cycle to optimise overall performance. A systems approach, if broadly applied, could reduce the barriers between stakeholders along supply chains.

  • (2008) Lundie, S; Peters, G; Rowley, HV; Schulz, M; Salem, J
    Conference Paper
    A life cycle assessment (LCA) was used to evaluate the influence of choosing refrigerants R22, R407C or R410A for domestic air conditioners. Other than the chemical characteristics of R22, the other key factor was the operating pressure. Due to high pressure operation, the R410A system experienced the highest leakage rate, energy consumption and global warming potential (GWP). Sensitivity analysis was used to examine the influence of leakage and to show that, compared with the unit’s lifespan, setpoint and efficiency, the climate in different Australian locations and the load profile have significant effects on the energy use and GWP.

  • (2009) Forbes, Gareth Llewellyn; Randall, Robert Bond
    Conference Paper
    The non-intrusive measurement of the condition of blades within a gas turbine would be a significant aid in the maintenance and continued operation of these engines. Online condition monitoring of the blade health by non-contact measurement methods is the ambition of most techniques. The current dominant method uses proximity probes to measure blade arrival time for subsequent monitoring. It has recently been proposed however, that measurement of the turbine casing vibration response could provide a means of blade condition monitoring, and even give the prospect of providing an estimation of the blade modal parameters. The casing vibration is believed to be excited pre-dominantly by (i) the moving pressure waveform around each blade throughout its motion and (ii) the moments applied by the stationary stator blades. Any changes to the pressure profile around the rotating blades, due to their vibration, will in turn affect these two dominant excitation forces, such that there will be some correlation between the casing response and blade vibrations. Previous work has introduced an analytical model of a gas turbine casing, and simulated pressure signal, associated with the rotating blades. The effect of individual rotor blade vibrations has been developed in order to understand the complex relationship between these excitation forces. A simplified turbine test rig has been constructed. Various aspects of the previous analytical modelling are presented, and then investigated and verified using results from the experimental program with this simplified test rig.

  • (2008) Caresta, Mauro; Kessissoglou, Nicole
    Conference Paper
    A model to describe the low frequency dynamic and acoustic responses of a submarine hull subject to an eccentric harmonic propeller shaft excitation is presented. The submarine is modelled as a fluid-loaded, ring stiffened cylindri-cal shell with internal bulkheads and conical end caps. The stiffeners are introduced using a smeared approach. A harmonic axial force is introduced by the propeller and is transmitted to the hull through the shaft. It results in excita-tion of the accordion modes only if the force is symmetrically distributed to the structure. Otherwise the excitation can be modelled as the sum of a distributed load and a moment applied to the edge of the hull. This leads to excitation of the higher order circumferential modes that can result in high noise signature. Structural and acoustic responses are presented in terms of deformation shapes and directivity patterns for the radiated sound pressure. Results for the case of purely axisymmetric excitation and the case in which an eccentricity is introduced are compared.

  • (2008) Cox, Shane Joseph; Hanna, Jessica; Antony, Alice; Negaresh, Ebrahim; Richardson, Des; Leslie, Greg
    Conference Paper
    The paper and pulp industry produces effluent which is high in organic content and salinity, typically making is difficult to treat. For reclamation of this wastewater, the process should be designed such that the water is ‘fit for purpose’. Agricultural reuse of this waste stream is a potential option as the treatment requirements are less intense than for other reuse opportunities. This papers forms part of a larger project for developing an integrated UF-NF-RO system for reclaiming the biologically treated effluent from a thermo-mechanical pulp and paper mill in rural Australia. The current work has characterised the waste water and investigated a suite of commercially available NF membranes as a pre-treatment method for RO. Dead-end stirred cell filtration has been used to evaluate the selective removal of multivalent ions and low molecular weight organics in the NF stage. The result demonstrate the importance of the NF stage to the reclaimed water and show a SAR reduction of between 30-60% is achievable in this system. Of the commercially available membranes tested the membrane which performed the best was the NTR-7450 membrane from Hydranautics.

  • (2009) Forbes, Gareth Llewellyn; Randall, Robert Bond
    Conference Paper
    The non-intrusive measurement of blade condition within a gas turbine would be a significant aid in the maintenance and continued operation of these engines. Online condition monitoring of the blade health by non-contact measurement methods is obviously the ambition of most techniques, with a number of methods proposed, investigated and employed for such measurement. The current dominant method uses proximity probes to measure blade arrival time for subsequent processing. It has been recently proposed however, that measurement of the turbine casing vibration response could provide a means of blade condition monitoring. The casing vibration is believed to be excited pre-dominantly by (i) the moving pressure waveform around each blade throughout its motion and (ii) the moments applied by the stationary stator blades. Any changes to the pressure profile around the rotating blades, due to their vibration, will therefore in turn affect these excitation forces. Previous work has introduced an analytical model of a gas turbine casing, and simulated pressure signal associated with the rotating blades. The model has been extended in this paper to more closely represent a commercial gas turbine with experimental verification being presented for various aspects of the analytical modelling procedure.

  • (2008) Efatmaneshnik, Mahmoud; Reidsema, Carl
    Conference Paper
    An ideal Multi Agent System is flat and has no dominant hierarchy. Multi agent computational and problem solving environments have been advocated for their ability to deliver overall solutions that are innovative and creative. There is however a significant threat to the coherence of Multi Agent Systems; chaos. This paper poses a new vision to the control and immunisation of the Multi Agent Systems against chaos. Employing a complexity measure of the problem and its lower and upper bounds, and monitoring the complexity of the problem solving agents’ interactions, we propose the holistic control of the Multi Agent Systems that leads to immunisation of the system against chaos. The control however is not central and appears in the form of the agents’ common knowledge and determines their tendency to proactively communicate.

  • (2008) Zhu, Liming; Staples, Mark; Tosic, V.
    Conference Paper
    Many industries have been developing e-business standards to improve business-to-business interoperability on a mass scale. Most such standards are composed of business data models with some message exchange patterns. Such data-only standards leave a very large interpretation space for the implementation stage at each individual organization. Thus, true industry-wide interoperability is still hard to achieve. In this industry report, we describe our experiences in creating and evaluating reference architectures for the Australian lending industry. To achieve the right level of prescriptiveness, our reference architectures are deliberately non-structural. Instead, they are based on a set of quality-centric architectural rules. We devised new methods for analyzing interoperability and evaluating such industry-level reference architectures. The first reference architecture has now been adopted and achieved positive effects. We also summarize several other lessons we learned, such as the need to align reference architectures with industry structures.

  • (2008) Caresta, Mauro; Kessissoglou, Nicole
    Conference Paper
    A model to describe the low frequency dynamic and acoustic responses of a submarine hull subject to a harmonic propeller shaft excitation is presented. The submarine is modelled as a fluid-loaded, ring stiffened cylindrical shell with internal bulkheads and end caps. The stiffeners are introduced using a smeared approach. The bulkheads are modelled as circular plates and the end closures as truncated conical shells. The propeller introduces a harmonic axial force that is transmitted to the hull through the shaft. It results in excitation of the accordion modes only if the force is symmetrically distributed to the hull. Otherwise the excitation can be modelled as the sum of an axisymmetric axial force plus a moment applied to the edge of the hull to take into account the eccentricity of the force. This leads to excitation of the higher order circumferential modes that can result in high noise signature. Structural and acoustic responses are presented in terms of frequency response functions of the axial and radial displacements and directivity patterns for the radiated sound pressure. Results for the case of purely axisymmetric excitation and the case in which an eccentricity is introduced are compared.

  • (2008) Alshroof, Osama; Reizes, John; Timchenko, Victoria; Leonardi, Eddie
    Conference Paper
    A numerical investigation has been performed to determine the effect on heat transfer in the laminar regime of introducing a single protrusion in a rectangular channel. The geometry consists of a three dimensional channel 10 mm high, 40 mm wide and 290 mm long in which a spherical protrusion was placed 90 mm from the inlet on the centreline of one of the wide sides. The print diameter of the obstacle was equal to the height of the channel and it protruded 2.2 mm above the surfaces. A commercial code, ANSYS-CFX11.0 was used for all simulations. The resultant very complex flow and thermal fields in the channel are discussed in detail. The presence of the protrusion results in an enhancement in the total heat transfer rate of 7% above that of a channel lined with flat plates only. This is a worthwhile increase since it is brought about by a pressure increase of only 1%.