Abstract This body of work entailed the broad contrasting of two hydrocarbon fuel auto-ignition models formulated for the emulation of combustion dynamics in Homogeneous Charge Compression Ignition (HCCI) engines. The first (empirical) auto-ignition model was adapted from its previously published form, for HCCI engine model implementation. This model was then combined with an explicit, single zone, thermodynamic engine model in order to investigate combustion phasing control strategies over ...
Abstract Water is not only essential for maintaining life; it is a key component of sustainable social and economic development having links to, inter alia, health, “sense of place”, food production and industrial growth. Although progress has been made with regard to water supply, it is estimated that there are still 2.4 million people in South Africa without access to adequate water and sanitation services as defined by the United Nations (Statistics South Africa, 2008). It is possible...
Abstract This research forms part of an ongoing HCCI study at the SASOL Advanced Fuels Laboratory to investigate and understand engine configuration and fuel chemistry effects on combustion in HCCI engines. This project continues from a previous project where a small Progress Aero Works (PAW) 6.5cc high speed model diesel" aeroplane engine was found to operate in HCCI mode with surprising ease and exibility. A 25cc, four-stroke, single cylinder Honda GX25 engine, possessing 2-valves with an o...
ABSTRACT BIOLOGICAL SULPHATE REDUCTION USING PRIMARY SEWAGE SLUDGE AS ENERGY SOURCE IN AN UPFLOW ANAEROBIC SLUDGE BED REACTOR Since the economics of biological sulphate reduction (BSR) are driven by the economics of the organic carbon source, the BioSURE® process has been developed as a low-cost effective system where primary sewage sludge (PSS) is used as the energy source. This research investigates the use of PSS for BSR in an upflow anaerobic sludge bed (UASB) reactor in detail in ord...
ABSTRACT The effect of impurities on the precipitation behaviour of nickel powder produced by high-pressure hydrogen reduction was investigated in order to determine the factors responsible for the formation of powder with undesirable morphology. In nickel precipitation by hydrogen reduction, two product morphologies have been observed: the spherical, open powder (desirable) and the spherical, closing/closed powder (undesirable). Two major impurities were studied namely; a morphology modifie...
Blast loading of sandwich panels with thin-walled tube cores
Abstract A 3-phase Z-source inverter has been researched, designed, simulated, built and tested. The purpose of the inverter is to deliver 3-phase 400 VAC from a DC supply that can vary over a range of 20 to 70 Vdc. This is done with a Zsource inverter topology which is a single conversion method with no additional DC to DC boost converter. A novel DSP control algorithm allows the inverter to achieve the following: · Run Space Vector Pulse Width Modulation (SV-PWM) for maximum DC bus voltag...
Abstract The geomemc deformalion induced by ([0 equal blast loads on uppositt sides of a thin-walled square tube ",ill weaken the siruclure. This will improve i[s energy absorbrioll charanenstics compared to a gcomccrically "perfect" square tube of the same size by reducing me crush load when cOlnpressed i11 the axial direction. Different types of impcrfcnioll can be induced depending on the Sl?e of the blast loads. Consequent to the blast loads, high temperalures ""ill also be induced by a...
Abstract The characterization and classification of liquids through instrumentation is essential in many industries. As such, measuring the characteristics of liquids is not just useful as a control parameter within an industrial process; such measurements can also be used to classify the liquid. Such a sensor is especially practical if it can be connected in-line with the liquid to be measured, thus minimally influencing flow. A piezoceramic tube was studied in an attempt to produce a senso...
ABSTRACT The efficiency of mixing processes in impeller agitated tanks depends highly on the hydrodynamics. Computational fluids dynamics (CFD) provides a method of predicting the complex tlow structures in stirred tanks. As with any approximate numerical method, CFD methods are subject to errors due to assumptions in the underlying mathematical models, as well as errors due to the numerical solution procedures. The aim of this thesis was to present a CFD method that accurately models the hy...
Abstract All real systems experience input saturation. Since the first proportional controller was implemented, systems have been susceptible to saturation. The introduction of the proportional-integral (PI) controller complicates matters further, since it reduces the steady state error to zero for zero-order setpoint tracking. This encompasses a fair portion of the implemented control strategies in the world. It is clear that saturation, by limiting the input state for the process, limits t...
ABSTRACT South Africa is possibly facing the biggest housing backlog in its history, and the backlog is growing annually. The ability and means to deliver must be improved, together with a compromise between the construction materials used and the occupants' preferences. This study seeks to examine the use of concrete block construction for the wall superstructure of low cost housing in terms of affordability and acceptability by the end-users. Three objectives of this research study, which ...
Abstract This thesis examines the use of 3D visualisation over the Internet as a tool for analysis and presentation of the Laetoli footprints. It describes the data used in the project and the methods used for checking and processing the data. Principles for creating 3D models are explained in detail. The tools used in the project are discussed, particularly VRML-based tools and how these tools integrate with the Internet. The discussion includes the design of the tools, which have been writ...