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 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...
Blast loading of sandwich panels with thin-walled tube cores
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 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 Continuum and finite element formulations ofthe static and dynamic initial-boundaryvalue evolution (elastoplastic) problems are considered in terms of both the classical and internal variable frameworks. The latter framework is employed to develop algorithms in the form of convex mathematical programming and Newton-Raphson schemes. This latter scheme is shown to be linked to the former in the sense that it expresses the conditions under which the convex non-linear function can be m...
ABSTRACT Several theories of creep and creep rupture are reviewed. Specific attention is devoted to the brittle damage theory proposed by Kachanov. Creep, damage and life predictions for rectangular or circular cross section beams under bending and tensile loads are presented. Comparison with data for a Ni Superalloy showed life predictions could be 30X in excess of experimental values. This beam model also revealed that it is imperative that no bending moments be inadvertently applied during...
ABSTRACT Coal is one of the most importa~t energy resources in South Africa. It covers 80% of the country's energy needs and provides valuable foreign exchange and employment. The purpose of this thesis is to provide an analytical framework for the examination of the demand for coal for the generation of electricity where more than 50% of the coal produced in the country is consumed. More specifically, the aim of the thesis is to identify the factors influencing the demand for steam-coal, dis...
Abstract Selection of optimum machining parameters is an essential factor in process planning for efficient metal cutting operations. In this study, an artificial neural network- based tool wear predictive model and a genetic algorithm-based optimization model were developed to determine the optimum cutting parameters for turning NST 37.2 steel with uncoated carbide cutting inserts. Multi-layer, feed-forare, back -propagation network was used in predictive model, while maximum metal removal r...
ABSTRACT Tool wear measurement is of great concern in machining industry, as it affects the surface qualities, dimensional accuracy and production costs of the machined components. The orthodox methods of measuring tool wear are time consuming and limited in accuracy and application. In this study, machine vision system based on digital image processing was developed for measurement of tool wear. The basic components of the system are: a charge coupled device (CCD) camera, PC, Microsoft Wind...
ABSTRACT Energy benchmarking and carbon footprint reduction opportunities in Portland cement manufacturing processes in Nigeria are presented. Life Cycle Assessment (LCA) is used to estimate the environmental impact of three cement manufacturing processes in Nigeria. The energy consumption of the cement manufacturing processes are evaluated using energy Benchmarking and Energy Savings Tool for cement (BEST-Cement). BEST-Cement evaluates and compares the energy consumption of the cement manuf...
Abstract The Design of an Efficient Solid Waste Management and Disposal Scheduling System in a metropolis is hereby presented. The design employed ten landfill sites in contrast to the existing one landfill site in the metropolis. The metropolis was divided into ten zones and a Hungarian mathematical model was used to get the optimal assignment of the proposed landfill sites to the zones. This model was applied to the field data obtained from the road net-work of Enugu metropolis and Enugu S...
ABSTRACT This study is about the production and characterization of epoxy-rice husk ash composite. Composites were produced at 10%,20%,30%,40% and 50% volume fraction of Rice Husk Ash(RHA) fillers and the epoxy was cast neat at 0%RHA which served as the control .The microstructure of the composites were studied with Scanning Electron Microscopy(SEM) and Energy Dispersive X-ray Spectroscopy(EDX).Mechanical properties of the composites such as tensile properties(tensile stress, tensile strain,...
Abstract: This study investigates the Indoor Air Quality (lAQ) of a room apartment and focused on the number of occupants that a space or an apartment can accommodate as a result of increase in the concentration level of the CO2 contaminant present within the space. The law of mass action was applied to generate a relation between the concentration of CO2 produced and the concentration of the reactants (i.e., O2 and CO). A decay equation was also used to relate the variation in the number of...
ABSTRACT This work deals with the multi-faceted impact of gas flaring on a global scale and the different approach employed by researchers to measure gas flared and its resulting emissions. It gives an overview of methods employed by these researchers in the oil and gas industry, academia and governments in attempt to determine ways of measuring and reducing gas flaring and its emission drastically. This approach so far includes analytical studies, numerical studies, modeling, computer simul...