The South African based petrochemical company, SASOL, operates three large plants for the recovery and purification of the chemical 1-hexene. The thermodynamic models available in commercial simulation packages fail to predict or correlate the plant data presently observed by SASOL. The focus of this project is the accruement of comprehensive and accurate modelling parameters that would assist SASOL in optimizing the operation of the three plants and meet their purity specifications. The experimental requirements of the project are the measurement of isothermal vapour-liquid equilibrium (VLE) data for selected binary systems, using a dynamic still. The binary systems investigated were 1-hexene + n-methylpyrrolidone (NMP) at 40, 62 and 90 °C, water + NMP at 70, 90 and 107 °C and 1-hexene + 3methylcyclopentene (3MCP) at 40, 50 and 60 °C. With respect to the modelling of the VLE data, the combined (gamma-phi) and direct (phi-phi) regression procedures were utilized. The results of the analysis show the combined method as the more flexible of the two, when used for low pressure systems. The excess Gibbs energy correlations investigated were the Margules, Van Laar, Wilson, NRTL and UNIQUAC. The NRTL and Van Laar models dominated the modelling results across the range of temperatures for each binary system and for both the direct and combined methods of data regression. The experimental data for the systems of water (1) + NMP (2) at 107 °C and at 70 °C were compared to literature data. The first system showed excellent correlation with the literature results while the second plot at 70 °C showed a positive bias of the experimental data between xj of 0.3 and 0.8. Thermodynamic consistency tests for the VLE data are also required to verify the accuracy of the data. For this project, the point and direct (Van Ness) consistency tests were used as the area test was considered as too mild. All systems passed the point and direct tests for the combined method and therefore verify the thermodynamic consistency of the experimental data. The systems failed in most cases for the direct method as the combined method is the more flexible of the two modelling methods. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2007.

This thesis involves a study of the thermodynamics of liquid mixtures containing N-methyl-2pyrrolidone (NMP) and hydrocarbons or ethers. NMP is a polar liquid which is used in liquid extraction procedures for the separation of polar and nonpolar hydrocarbons. It was considered important enough to devote an entire thesis to the properties of NMP related to its interactions with simple hydrocarbons and ethers. The thesis consists of four parts: Part one is devoted to liquid-liquid equilibria. Experimental results at 298.2 K, are presented for the mixtures: NMP + an aromatic hydrocarbon + an n-alkane. Firstly, the effect increasing the chain length of the alkane has on the liquid-liquid equilibria was investigated, by studying mixtures of the type: an n-alkane + toluene + NMP; where the n-alkane refers to n-hexane or n-nonane or n-tetradecane or n-hexadecane. Secondly, the effect of substitution on the benzene ring on the equilibria was studied by measuring the liquid-liquid equilibria for the mixtures: n-hexadecane + an aromatic hydrocarbon + NMP; where the aromatic hydrocarbon refers to toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. The chain length of the n-alkane had a significant effect on the liquid-liquid equilibria. Methyl substitution on the benzene ring had a small effect on the liquid-liquid equilibria. Part two is devoted to activity coefficients at infinite dilution. Experimental results at 298,15 K, determined using gas-liquid chromatography, are presented for the mixtures: NMP (solvent) + n-pentane or n-hexane or n-heptane or n-octane or cyclopentane or cyclohexane or cycloheptane or I-hexene or 1-heptene or l-octene or diethyl ether or diisopropyl ether. The magnitudes of the infinite dilution activity coefficients had the following order: n-alkanes > cycloalkanes > l-alkenes > ethers. Part three is devoted to excess molar enthalpies. Experimental results at 298.15 K are presented for the mixtures: NMP + an aromatic hydrocarbon. Here, an aromatic hydrocarbon refers to one of benzene or toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. Isothermal flow microcalorimetry was used to determine the excess molar enthalpies. Increased methyl substitution on the' benzene ring manifests itself as a reduction in the association between NMP and the aromatic hydrocarbon. Part four is devoted to excess molar volumes. Experimental results at 298.15 K are presented for the mixtures: NMP + an aromatic hydrocarbon. Here, an aromatic hydrocarbon refers to one of benzene or toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. Densitometry was used to determine the excess molar volumes. The excess molar volumes were negative for all the mixtures. / Thesis (M.Sc.)-University of Natal, 1997.

The experimental work conducted in this thesis was aimed at determining the thermodynamic quantities associated with the formation of complexes formed between various metal ions and KELEX 100, a ligand which is used commercially for liquid - liquid extraction. In order to accomplish this, the beats of protonation of the ligand KELEX 100 were determined calorimetrically at 25°C in a partially aqueous medium of75% (v/v) l,4-dioxane and at an ionic strength of 0.1 mol dm·3• Extraneous heat effects that usually accompany complex formation were accounted for by measuring each heat contribution separately. The complexation of the lead (II), cadmium (II) and nickel (II) ions with KELEX 100 was studied in 75%(v/v) l,4-dioxane medium. The enthalpies of complexation were measured calorimetrically and calculated using the program LETAGROP KALLE. These results were combined with the values of the Gibbs free energies available in the literature for these systems to yield the entropies of complexation. In all calorimetric determinations a constant ionic strength of 0.1 mol dm'3 and a temperature of 25°C was maintained. The calculated enthalpies and entropies are discussed in terms of a number of factors that affect the thermodynamics of the systems. These factors include the structure of the ligand molecule, the nature of the donor atoms, the degree of substitution on the ligand and the properties of the metal atom such as charge and size, and the nature of the solvent. The cumulative enthalpies and entropies of formation of the metal-ligand complexes are favourable, Le. complexation is accompanied by a decrease in enthalpy and an increase in entropy. However, the enthalpy changes contribute more to the stability of the complexes and hence are the driving forces for complex formation. In the case of the Cd(II) ion, the enthalpy and entropy changes are similar. The cumulative enthalpies of formation increase (Le., become more exothermic) in the order: Ni > Pb > Cd while the reverse order is found for the entropies of formation. The smaller enthalpy change for the Cd(II) complex is possibly due to the weak interaction between the 'soft' Cd(II) ion and the 'hard' KELEX 100 ligand while the decrease in entropy for the Ni(II) may be due to the loss of fewer solvent molecules from the Ni(II) hydration sphere on complexation with the ligand. The stepwise entropy and enthalpy changes for the formation of the ML+ complexes are dependent on the ionic radius of the metal ion. However, no linear correlations exist between the cumulative entropy or enthalpy changes of formation of the ML complexes and the size of the metal ion. The stepwise and cumulative enthalpies of formation appear to be largely independent of steric effects of the bulky alkyl substituent on the KELEX 100 ligand. The increased steric hindrance of the substituent decreases the cumulative entropy change for the formation of the Ni(II) complexes. However, in the case of the Pb(II) complexes, steric effects do not appear to affect the cumulative entropies of complex formation. / Thesis (M.Sc.)-University of Natal, 1995.

This thesis is presented in two parts. In part one, the excess molar volumes and the excess molar enthalpies have been determined for several binary systems at 298.15 K using an LKB flow microcalorimeter and/or a 2277 Thermal Activity Monitor and an Anton Paar Digital Densitometer. The excess molar volumes and excess molar enthalpies, V; and H; , have been determined for systems involving an alkanol (I-propanol, 2-propanol) mixed with a hydrocarbon (1hexene, I-heptene, l-octene, I-hexyne, I-heptyne, l-octyne). The results show trends relating to the degree of unsaturation of the hydrocarbon to the position of the hydroxyl group on the alkanol. The excess molar volumes and excess molar enthalpies, V; and H; of di-n-butylamine + diethyl ether or dipropyl ether or di-l-methylethyl ether or dibutyl ether or 1,1 dimethylethyl methyl ether or 1,1 dimethylpropyl methyl ether or tetrahydrofuran or tetrahydropyran or 1,4 dioxane have been measured over the whole composition range at the temperature 298.15 K in order to investigate di-n-butylamine - ether interactions. The V; values for each of the systems studied are negative with the exception of the mixtures of (di-n-butylamine + dibutyl ether or tetrahydrofuran or tetrahydropyran or 1,4 dioxane. The H; results over the whole mole fraction range are formed endothermically. Measurements were also made on mixtures involving (a cycloalkane + a pseudocycloalkane). The congruency theory was tested for the (cycloalkane + pseudo-cycloalkane) mixture. The cycloalkane mixtures studied here did not satisfy the null test of the congruency principle. In the second part of this thesis the main aim of the investigation was to apply ambient temperature hydrogen peroxide bleaching techniques to a novel non-woven fabric and to optimize the treatment conditions for this technique. Five cold-pad batch bleaching formulas were applied to the non-woven and the sample fabrics were analyzed for the following properties a) fluidity (measure of degree of degradation of the cotton fibre as a result of the bleaching process) b) wettability (absorbency) c) whiteness (using instrumental techniques) d) inherent fibre surface properties (SEM) A method was elucidated for the cold batch bleaching of the non-woven which produced a fabric with minimum fibre damage, an acceptable degree of whiteness and excellent absorbency properties. The treatment parameters of time (Xl), temperature(x2) and hydrogen peroxide concentration (x3) for this method were optimised using a multiple regression analysis for three variables and response surface plots. / Thesis (M.Sc.)-University of Natal, Durban, 1993.

The development of magnox fuel cans at the Heston Laboratories of A.P.C. Ltd. required a non-contact method of measuring fuel can temperature during heat transfer tests. Infra-red techniques were examined and a two colour ratio pyrometer was selected as offering the greatest prospect of success. A design specification was compiled for an instrument having a lower temperature limit of 250°C with a target area of approximately 1mm². During heat transfer tests a pressurised rig is used and an observation window is necessary. This leads to some deterioration in performance which it is impracticable to remove by internal chopping and the pyrometer is designed for outside use. Operational wavebands around 1.8 and 2.3 microns are chosen and a lead sulphide infra-red detector operating at room temperature is selected. The properties of the detector lead to a design where the signal is chopped at 900 cps and modulated at 30 cps by the energy in each waveband. Conventional optical systems are considered and rejected in view of the large size of chopper wheel necessary. An alternative system is devised in which a commercially available pencil galvanometer is used to combine the function of chopping at both 900 cps and 30 cps. This enables an optical system to be designed which, because it employs reflecting optics, is compact and for the most part axially symmetric. The signal ration is extracted using an automatic gain control technique and a high signal to noise ratio is achieved with a phase sensitive rectifier at the output. The pulses which activate the galvanometer chopper and phase sensitive circuits are derived from a master oscillator operating at 900 cps. The performance of the system is assessed and it meets the specification in all respects except for a small surface geometry effect. The underlying cause for this is examined and a means for overcoming it is suggested. The performance when scanning a magnox can during bench tests is illustrated and it can be seen that although agreement to within 2°C is obtained with thermocouples placed at the fin roots, the geometry effect prevents the isolation of fin tip temperature. During the development of the instrument the possibility of wider application was an important consideration. Some of the applications which have arisen are discussed briefly and an indication of the performance of the pyrometer is given. Furthermore the system is capable of easy modification for use with a cooled detector and other regions of the infra-red spectrum.

During July 2005, Typhoon Banyan recurved and underwent tropical transition over the western North Pacific. Coincident with the extratropical transition of Banyan, a large mid-tropospheric anticyclone developed immediately east of the recurving typhoon. The anticyclone was associated with a high-amplitude Rossby wave-like pattern that developed downstream of the anticyclone and extended across the North Pacific. Development of the anticyclone is examined with respect of the interaction between the outflow from Banyan and the midlatitude jet streak. During the poleward movement of TY Banyan, an anticyclonically-curved jet streak was forced by the merger of the upper-level outflow from Banyan and a jet streak associated with an upstream trough. The anticyclonic curvature was accentuated by the presence of a mid-tropospheric cyclone east of Banyan. The anticyclonic curvature increased as Banyan moved poleward and the mid-tropospheric cyclone moved equatorward. Thermodynamic forcing of the mid-tropospheric anticyclone is examined with respect to the poleward movement of warm moist air that ascends as it is advected around the eastern side of the decaying typhoon. The combination of dynamic and thermodynamic factors is examined in a potential vorticity framework to identify the development of the anticyclone east of Banyan and the transformation of Banyan into a midlatitude cyclone.

The Palaeoproterozoic Birimian terrane of the West African Man Shield is a gold province of global importance. Gold mineralization at the Damang deposit, however, is unique amongst known gold deposits in Ghana. It comprises a stratigraphically controlled auriferous quartz-pebble conglomerate, which is overprinted by later orogenic gold contained in a sub-horizontal fault-fracture quartz vein array. Furthermore, this gold mineralization is hosted in sediments of the Tarkwaian System, rather than volcanics of the underlying Birimian Supergroup. This thesis integrates petrological, geochemical, thermodynamic and geochronological data to investigate the Damang deposit in the context of the regional tectonic and metallogenic framework. Staurolite-grade, amphibolite facies peak metamorphism at Damang occurred at around 595ºC and 5.5 kbar at 2005±26 Ma. This was immediately followed by a short period (~ 5 Ma) of rapid exhumation, at a rate of approximately 2.6 mm/yr. This decompression led to the formation of the fault-fracture mesh, which was enhanced by the silicification of host rocks during an earlier ‘Pink Haematite’ hydrothermal event that was associated with the intrusion of voluminous dolerite bodies. Orogenic gold mineralization occurred at the end of this exhumation period at conditions of 400–450ºC and 1–2 kbar. These conditions are in broad agreement with other Ghanaian deposits. A gold-bearing, CO₂-rich (X(CO₂) ~ 0.7), aqueous fluid generated through metamorphic devolatilization reactions close to peak metamorphism and during the subsequent exhumation fed the fault-fracture mesh. This fluid imparted a potassic–carbonation–sulphidation alteration overprint similar to that seen at orogenic gold deposits globally. This alteration signature is characterized and identified with portable infrared spectroscopic techniques. Exhumation rates following gold mineralization were less than 0.01 mm/yr, while ⁴⁰Ar/³⁹Ar dating of biotites give ages ranging between 1978.8±6.2 Ma and 1898±11 Ma, indicating extremely prolonged (~ 80 Ma) cooling through the interval 300–250ºC. Ultimately, this thesis demonstrates that the Damang deposit is part of the same regional metallogenic event that formed the other Ghanaian deposits. This implies that the Tarkwaian System elsewhere in Ghana may be prospective for orogenic gold mineralization.

A Thesis submitted to the faculty of Engineering, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy / Thermodynamic analysis techniques for the study of combustion in compression ignition engines were developed and refined. The techniques were validated against test runs of diesel fuelling, and were then applied to the almost unexplored case of combustion of aspirated dimethyl either (DME) acting as ignition promotor and supplementary fuel, and injected methanol as main fuel. Combustion chamber pressure versus crank angle data were captured for single engine cycle on normal fuelling (methanol and DME), fuelling with DME alone and pure motoring (no fuel) all at essentially identical engine conditions. These data were analysed by a number of mutually complementary techniques. / AC2017

This experim ental project aims to describe the influencing factors in the vacuum boiling o f w ater in w ater vapour refrigeration system s Testing was conducted using a 2 kW three-stage steam je t ejector system, w ith barom etric condensers, as the com pression device. Three direct-contact evaporators were used to investigate the boiling phenom ena. T hese were : a through-flow evaporator w here heal and mass transfer rates were established for boiling m echanism s at various positions within the evaporator; a vertical cylinder where small quantities o f w ater were subjected to rapid decom pression and the effects m easured, and a sim ple channel for photographic studies o f the process. Boiling in direct-contact water vapour systems is described herein The vacuum boiling proo ss was found to be controlled by a com bination o f the w ater surface tem perature and the hydrostatic pressure gradient, these being governed by the w ater vapour flow geometry between the w ater surface and ejector suction and convective heat transfer below the boiling region. The contributions o f the various boiling regim es to the total heat transfer are discussed. Heat and mass transfer coefficients and their applicability to evaporator design are presented

How is it that the Roman decadence, a derogatory term during the Enlightenment, became the fundamental aesthetic reference for a nineteenth century literary movement? Focusing on the intersections of literature, politics, religion, science and art history, this dissertation adopts a diachronic approach to decadence, read against a backdrop mobilizing twentieth century philosophers Vladimir Jankelevitch and Michel Serres. Decadence (Latin cadere, to fall) first designated the fall of the Roman Empire and a falling away from its political, moral and aesthetic norms. Drawing on Petronius and Baudelaire, I crystallize three ways in which philosophers, scholars (“érudits”), and poets faced the troubling notion of the fall : they observe its occurrence, restore its ruins, or praise its beauty. With this in mind, the dissertation closely analyzes eighteenth century topoi that conceive decadence as political instability (Montesquieu, Gibbon), moral corruption (Rousseau, de Maistre), and architectural imbalance (Diderot, Seroux d’Agincourt). The principal emphasis is on the semantic and stylistic value assigned to the term “decadence”. These interdiscursive readings disclose the displacement of decadent topoi : shifting from one context to another, they narrate the fall of the Roman Empire and remain inscribed in the literary production of Decadence. Whereas the Enlightenment underlines the edifying dimension of the Roman example, nineteenth century authors, lapsing into original sin and propelled by thermodynamic loss, salute the expression of the fall. Barbey d’Aurevilly’s writings reveal consistent historical, structural and textual references to Roman topoi, caught up in the arrested completion of political and mechanical cycles. Furthermore, his dandyism and ultramontanism conjure up the Roman conflict, while recurring fragments, maculae and lacunae destabilize the architectural balance of his texts. The Literature of Decadence emerges as an artificial intervention that suspends the irreparable fall, enlightening the political, moral and technological turmoil of the Second Empire with those of the Roman Empire. In returning Decadence back to its Roman origins, and tracing their configuration in the age of Enlightenment, this dissertation unravels a formative, yet frequently overlooked component of nineteenth century literature and aesthetics.