An experimental study was conducted using axisymmetric co-flow laminar diffusion flames of methane-air, methane-oxygen and ethylene-air to examine the effect of pressure on soot formation and the structure of the temperature field. A liquid fuel burner was designed and built to observe the sooting behavior of methanol-air and n-heptane-air laminar diffusion flames at elevated pressures up to 50 atm. A non-intrusive, line-of-sight spectral soot emission (SSE) diagnostic technique was used to determine the temperature and the soot volume fraction of methane-air flames up to 60 atm, methane-oxygen flames up to 90 atm and ethylene-air flames up to 35 atm. The physical flame structure of the methane-air and methane-oxygen diffusion flames were characterized over the pressure range of 10 to 100 atm and up to 35 atm for ethylene-air flames. The flame height, marked by the visible soot radiation emission, remained relatively constant for methane-air and ethylene-air flames over their respected pressure ranges, while the visible flame height for the methane-oxygen flames was reduced by over 50 % between 10 and 100 atm. During methane-air experiments, observations of anomalous occurrence of liquid material formation at 60 atm and above were recorded. The maximum conversion of the carbon in the fuel to soot exhibited a strong power-law dependence on pressure. At pressures 10 to 30 atm, the pressure exponent is approximately 0.73 for methane-air flames. At higher pressures, between 30 and 60 atm, the pressure exponent is approximately 0.33. The maximum fuel carbon conversion to soot is 12.6 % at 60 atm. For methane-oxygen flames, the pressure exponent is approximately 1.2 for pressures between 10 and 40 atm. At pressures between 50 and 70 atm, the pressure exponent is about -3.8 and approximately -12 for 70 to 90 atm. The maximum fuel carbon conversion to soot is 2 % at 40 atm. For ethylene-air flames, the pressure exponent is approximately 1.4 between 10 and 30 atm. The maximum carbon conversion to soot is approximately 6.5 % at 30 atm and remained constant at higher pressures.

The thermodynamic knowledge of accurate phase equilibrium data plays an important role in the design and optimization of separation processes in chemical and engineering industries. Vapour-liquid equilibrium data are essential for the design of efficient separation processes such as distillation. The presented research study is mainly focused on the vapour-liquid equilibrium data measurement of fluorochemical and hydrocarbon binary systems at various temperatures and at high pressures. A new static analytical apparatus was constructed and commissioned for the measurement of accurate and precise vapour-liquid equilibrium data at temperatures and absolute pressures ranging from low temperatures to 323.15 K and 0 to 10 MPa respectively. The new apparatus incorporates the ROLSI TM sampler, a sampling technique developed by the CEP/TEP laboratory in Fontainebleau, France. Isothermal high pressure VLE data were measured for three binary systems comprising of hexafluoroethane (R116) + propane, HFPO + propane and ethane + octafluoropropane (R218). The R116 + propane system at 263.15 K was measured as a test system using the new static apparatus. These measurements helped to confirm the functioning of the experimental apparatus. The reliability and the reproducibility of the experimental procedure were also checked. The data obtained were in excellent agreement with data in the literature. Thereafter, measurements of previously unmeasured systems were undertaken. Isothermal vapour-liquid equilibrium data measurements for the ethane + octafluoropropane system were performed at five isotherms with temperatures and pressures ranging from 264.05 to 308.04 K and 0.298 to 4.600 MPa respectively. The five isotherms constitute new experimental data. The HFPO + propane system was also investigated and vapour-liquid equilibrium data were measured at three isotherms (283.05, 303.05 and 323.05 K) with pressures ranging from 0.437 to 2.000 MPa. The data measured also constitute a set of a new HPVLE data. The uncertainties in the measurement for both systems were within ± 0.09 K, ± 0.0016 MPa and less than 2% for temperatures, pressures and mole fractions, respectively. All experimental data were correlated via the direct method using the Peng-Robinson equation of state with the Mathias-Copeman alpha function and the Wong-Sandler mixing rules incorporating the NRTL activity coefficient model. The consistency of the measured VLE data was tested using the Van Ness point test which yielded few points of difference between the measured and calculated data, suggesting a low error rate. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

Modifications were undertaken to a static high pressure vapour-liquid equilibrium (VLE) apparatus described by Naidoo [2004]. The alterations were made to improve the sample analysis technique. These modifications included the incorporation of the ROLSITM sampling device into the equilibrium cell, a re-design of the air bath which improved the temperature profile and further alterations described in the text. The equipment has an operating temperature range of 278.15 K to 473.15 K and pressure range of absolute vacuum to 150 bars. The apparatus consisted of an agitated cell in an air-bath. The uncertainties in the temperature and pressure measurements were ±0.02 K and ±4 kPa respectively. A Shimadzu Gas Chromatograph, Model 2010 was used for sample analysis. An initial test of the apparatus was carried out to measure the pure component vapour pressure data for propane and ethane in the temperature range of 279.24 – 360.18K and the results concurred with literature data (absolute relative deviation <0.153%) The experimental procedure used in this study was developed from the technique used by Ramjugernath [2000], with some minor changes implemented only to achieve some requirements for problems encountered during the project. Isothermal binary measurements for the hexafluoroethane (R116) + propane system were used as test system to investigate the accuracy and reliability of the equipment. Three binary isotherms were measured at 291.22 K, 296.23 K and 308.21 K. The measured data compared well with literature data. Particular attention was placed on the fluorinated hydrocarbons. Specific properties of fluorinated hydrocarbons give them many applications in industry, such as solvents, refrigerants, propellants, anaesthetics, etc. Hence, a phase equilibria study of a fluorinated hydrocarbons system was carried out in this project. The commissioning of the equipment was successfully undertaken and the equipment was found to be efficient and reliable. As a consequence measurements were made on the hexafluoropropylene oxide (HFPO) + ethane system. No data has been previously published in literature for this system. Measurements were undertaken at five different temperatures, 283.15 K, 290.15 K, 298.15 K, 308.15 K and 318.15 K. The isotherms were chosen in order to have measurements below and above the critical temperature of ethane, in order to see the transition at the critical temperature. The experimental data were modelled via the direct (phi-phi) method. The Peng-Robinson equation of state was applied, including the Mathias-Copeman alpha correlation with the Wong- Sandler mixing rules incorporating the NRTL activity coefficient model. Good agreement was found between the correlated and the measured data. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.

The objective of this project is to optimize the SAPREF oil refinery steam distribution in which imbalances between the various levels presently require the venting of steam from the lowest level. The overall steam balance shows that the problem originates from an excess of high·pressure (HP) steam production for too few medium pressure steam users and turbines. We proposed to solve this problem by considering the replacement of selected steam turbines with electrical drives. Given a set of demands of electricity, mechanical power and steam at various pressure levels, the objective is to recommend configuration changes to minimize overall cost. This is not a trivial problem, as steam not passed down through turbines to lower levels can create a shortage there, so a combination of replacements is required. The variables of the problem are both decision variables on every steam turbine and continuous variables, such as flows and enthalpies. These decision variables are integer variables, 0 or 1 for every steam turbine. Depending on whether it is kept on steam use or replaced with an electrical drive, these variables are as follows: E = 0: keep the existing steam turbine E - 1: switch it to an electrical drive. A complete and realistic model of this utility section must be constructed in order to represent the actual distribution accurately. This model will include an objective function to minimize, some equality and inequality constraints, and some cost functions. If we want this model to be accurate, we shall have to deal with nonlinearities to avoid simplifications, and these non-linearities could lead to infeasabilities or sub-optimal solutions. So we are facing a typical MTNLP (Mixed Integer Non-Linear Programming) problem to find optimal configuration changes which will maximize the return on investment, meeting the electrical, mechanical and steam demands of the refinery. In order to solve this difficult optimization problem we shall use the user-friendly package GAMS (General Algebraic Modeling System). / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2001.

In order to effectively model the behaviour of energetic materials under operational conditions it is essential to obtain detailed structural information for these compounds at elevated temperature and/or pressures. The structural characterisation of the high explosives RDX and CL-20 and a series of inorganic azides [Mn+(N3)n] at extreme conditions is described herein. In addition to the characterisation of a highly metastable β -form of RDX (1,3,5- trinitrohexahydro-1,3,5-triazine) at atmospheric pressure, the structure solution of a high-pressure/ high-temperature polymorph is described. This form, obtained above 4.3 GPa and 450 K, has been shown to be distinct from the β -form and has therefore been denoted - RDX. Furthermore, ε -RDX is sufficiently metastable to allow its recovery to ambient pressure at 150 K; it only transforms to the α -form upon warming to 230 K. Finally, the ambient-temperature compression of RDX has been investigated to a maximum pressure of 23.0 GPa, using methanol:ethanol (4:1) as the pressure-transmitting medium; no phase transition was observed under these conditions, other than the α → γ transition at 3.9 GPa. The structure of a high-pressure polymorph of CL-20 (2,4,6,8,10,12- hexanitrohexaazaisowurtzitane) has also been determined by a combination of powder and single-crystal X-ray diffraction. Compression of γ -CL-20 to above 0.7 GPa using Fluorinert (FC-77) as the pressure-transmitting medium results in a phase transition to the ζ -form, which has been found to display structural similarities with both theγ γ - and ε -forms. The high-pressure behaviour of CL-20, however, depends markedly on the starting polymorph and the pressure-transmitting medium selected. Compression of γ -CL-20 in MeOH:EtOH (4:1) results in the formation of a 2:1 CL-20:MeOH solvate at 0.5 GPa. This solvate is stable upon compression to P > 5.0 GPa. It may also be recovered to ambient pressure at 293 K. Meanwhile, no phase transition is observed during the compression of ε -CL-20 to a maximum pressure of 7.2 GPa. Finally, a series of inorganic azides [NaN3, CsN3, TlN3, NH4N3, AgN3 and Pb(N3)2] has been characterised under a range of pressure and temperature conditions. Of the six compounds studied, all displayed at least one polymorphic transition – 5 new forms have been structurally characterised in this work and evidence of another 5 is presented. The combined effect of pressure and temperature results in sodium azide adopting a tetragonal structure common to larger alkali metal azides. Caesium azide has been shown to undergo three phase transitions during compression to 6.0 GPa – the structure of the first high-pressure form is reported. A variable temperature X-ray powder diffraction study of TlN3 has allowed the structural characterisation of the low-temperature TlN3-IV (at 230 K) as well as providing evidence for a phase transition to a high-temperature form above 550 K. The high-pressure form III (obtained above 0.76 GPa) has also been determined by neutron powder diffraction. Silver, ammonium and lead(II) azides have all been shown to undergo a phase transition at high pressures. Compression of silver azide (P > 0.80 GPa) removes an orthorhombic distortion observed at atmospheric pressure, resulting in the tetragonal structure adopted by CsN3 and TlN3 under ambient conditions. Moreover, NH4N3 and Pb(N3)2 have been found to undergo phase transitions at 2.6 GPa, although their high-pressure structures have still to be determined.

Nanomaterials (NMs) are materials in which the size of at least one dimension is less than 100 nm. Examples include quantum dots, nanoparticles, “Buckminsterfullerene (C60)”, carbon nanotubes, graphene and TiO2 thin films. Many research groups have investigated the properties of NMs, and they have reported that some of them are clearly different to those of the bulk materials, and depend on the size of the NMs. Examples include melting temperatures, phase transition pressures, fluorescence spectra, catalytic properties and magnetic properties. Recently, a high-pressure study of Te nano-cylinders revealed compressibility effects that are different to those observed in bulk-Te. Although this study reported an elevation of phase transition pressure compared to the bulk, the authors did not investigate the structures of the high-pressure phases, and it is unclear whether the incommensurate phase found at high pressures in bulk-Te was observed or not. Indeed, it is completely unknown whether the incommensurate phases observed in a number of elements at high pressure also exist in nanoparticle samples of the same materials. The search for, and study of, such phases forms the subject of this thesis. Initial studies of commercial selenium nanoparticles (nano-Se) revealed that the incommensurate phase of bulk selenium (Se-IV) is also found in nano-Se. The transition pressures in nano-Se are slightly higher than those of bulk-Se. However, the nano-Se samples were subsequently found not to have the sizes, shapes, and properties claimed by the vendor, which was confirmed by transmission and scanning electron microscopy. Further commercial samples of nano-Se and nano-Bi were also found to be of extremely poor quality. It was clear, therefore, that a detailed study of incommensurate phases in NMs would require us to make our own samples. Bismuth nanoparticles (nano-Bi) with dimensions 51(6), 52(15), 92(13), 128(45), and 138(27) nm have been successfully synthesised by the author in collaboration with the Hybrid Nano Collods group at the University of St. Andrews. On compression, the nano-Bi samples were found to have the same order of phases Bi-I, Bi-II, Bi-III, and Bi-V and phase transitions as found in bulk-Bi, but were found to exhibit larger phase coexistence. The phase transition pressures on pressure increase were higher than those of the bulk materials, and the smaller the diameter of nano-Bi, the higher the phase-transition pressure. This behaviour is similar to, but more extreme than, that found in CdSe nanoparticles. The incommensurate Bi-III structure has been found in nano-Bi under increases in pressure. However, the di↵raction patterns from Bi-III contain additional unaccounted-for peaks, and this phase is referred to as complex Bi-III. The Debye- Scherrer rings from complex Bi-III are smooth, and do not exhibit the spottiness observed in the diffraction patterns of Bi-III obtained from bulk-Bi. This enables full Rietveld refinement of Bi-III in the nano-samples. Complex Bi-III exists from 3 GPa up to 30 GPa, compared to the stable range of only 2.7 to 7.7 GPa of Bi-III in the bulk material. While such a large range of pressure enables the structure of nano-Bi-III to be studied over a much wider pressure range than bulk-Bi-III, such studies were hampered by the existence of the unaccounted-for peaks. In order to get clean, single-phase patterns of Bi-III, samples of this phase were first prepared on pressure decrease from the higher-pressure Bi-V phase, before recompressing them. Single-phase samples of Bi-III were obtained and were found to be stable up to 14-18 GPa. However, because of phase coexistence, diffraction peaks from Bi-III were still visible at pressures as high as ~30 GPa, which is ~3 times larger than the upper limit pressure of existence of bulk-Bi-III. On pressure re-increase, nano-Bi-III has a higher bulk modulus than bulk-Bi-III. The bulk modulus was found to be size-dependent as it is higher when size decreases. Moreover, nano-Bi has a smaller value of the incommensurate wave vector, which is almost pressure independent, but is found to be particles size dependent. The incommensurate wave vector thus becomes another of the structural and physical properties of nanomaterials that is found to be sample-size dependent.

This work is devoted to generate knowledge and high quality experimental data of catalytic combustion at operational gas turbine conditions. The initial task of the thesis work was to design and construct a high pressure combustion test facility, where the catalytic combustion experiments can be performed at real gas turbine conditions. With this in mind, a highly advanced combustion test facility has been designed, constructed and tested. This test facility is capable of simulating combustion conditions relevant to a wide range of operating gas turbine conditions and different kinds of fuel gases. The shape of the combustor (test section) is similar to a “can” type gas turbine combustor, but with significant differences in its type of operation. The test combustor is expected to operate at near adiabatic combustion conditions and there will be no additions of cooling, dilution or secondary supply of air into the combustion process. The geometry of the combustor consists of three main zones such as air/fuel mixing zone, catalytic reaction zone and downstream gas phase reaction zone with no difference of the mass flow at inlet and exit. The maximum capacity of the test facility is 100 kW (fuel power) and the maximum air flow rate is 100g/s. The significant features of the test facility are counted as its operational pressure range (1 – 35 atm), air inlet temperatures (100 – 650 °C), fuel flexibility (LHV 4 - 40 MJ/m3) and air humidity (0 – 30% kg/kg of air). Given these features, combustion could be performed at any desired pressure up to 35 bars while controlling other parameters independently. Fuel flexibility of the applications was also taken into consideration in the design phase and proper measures have been taken in order to utilize two types of targeted fuels, methane and gasified biomass. Experimental results presented in this thesis are the operational performances of highly active precious metal catalysts (also called as ignition catalysts) and combinations of precious metal, perovskites and hexaaluminate catalysts (also called as fully catalytic configuration). Experiments were performed on different catalytic combustor configurations of various types of catalysts with methane and simulated gasified biomass over the full range of pressure. The types of catalysts considered on the combustor configurations are palladium on alumina (Pd/AL2O3), palladium lanthanum hexaaluminate (PdLaAl11O19), platinum on alumina (Pt/AL2O3),and palladium:platinum bi-metal on alumina (Pd:Pt/AL2O3). The influence of pressure, inlet temperature, flow velocity and air fuel ratio on the ignition, combustion stability and emission generation on the catalytic system were investigated and presented. Combustion catalysts were developed and provided mainly by the project partner, the Division of Chemical Technology, KTH. Division of Chemical Reaction Technology, KTH and Istituto di Ricerche sulla Combustione (CNR) Italy were also collaborated with some of the experimental investigations by providing specific types of catalysts developed by them for the specific conditions of gas turbine requirements. / <p>QC 20131125</p>

The focus of this project is to find a suitable method to determine the mixing ratio inbinary fluid mixtures in continuous-flow microfluidic systems because of thedifficulties in doing so for mixtures containing compressible fluids. Refractive indexand relative static permittivity are both properties that could be suitable, but methodsmeasuring the refractive index scales badly for microsystems. A microfluidic chip for measuring capacitance was placed on a PCB together with amixing structure with strain-relieved fluid and electrical interfaces. This PCB was builtinto a rig with two piston pumps and a backpressure regulator to makemeasurements of the relative static permittivity of air, ethanol, methanol, acetonitrile,liquid and gaseous carbon dioxide, as well as of several mixtures of ethanol andcarbon dioxide using a Network Analyzer. Several other measuring techniques were tried, but the Network Analyzer wassuperior in accuracy, stability and frequency range. It produced values within 4% ofthe theoretical, and the discrepancy could be explained by the approximations in theparallel plate capacitor formula, the capacitance contributions of the external parts ofthe system and surface roughness. The Network Analyzer is a good tool to determinethe mixing ratio in binary fluid mixtures in continuous-flow microfluidic systems.

A research report Submitted to the faculty of Health Sciences, University of Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Masters of Science in Medicine (Pharmaceutical Affairs). / Pathogenic mycobacterial infection was in recent decades a health concern so well controlled that eradication seemed imminent. However, it is once again reaching epidemic proportions following the increasing prevalence of AIDS. One important means of curbing this resurgence, is a robust method that has the capability of identifying to a species level speciating disease causing mycobacteria in a matter of days. Several new methodologies are now available that enable dramatic reductions in turn-around times. In this study High Performance Liquid Chromatography was investigated to determine how this system compared with the current mycobacterial system of methodologies adopted in South African laboratories. Four species of pathogenic mycobacteria, with a high prevalence in South Africa, were tested in a sample size of 80. Samples were subjected to HPLC, Gene Probes and Biochemical testing. HPLC was the most capable of identifying the mycobacteria to species level displaying a sensitivity to the organisms of 96.25 %. Gene probes and Biochemical testing had sensitivity values of 82.5 % and 80 % respectively. HPLC was also more cost efficient and displayed a wider range of identification. It is therefore suggested that HPLC replace Gene probes and Biochemical testing for purposes of MOTT identification in the comprehensive mycobacterial identification system. The result is a time saving of at least 3 weeks and a cost reduction of approximately 30 %. The large initial capital investment required for the implementation of the HPLC system is justified by the long term cost saving as well as the additional utility derived from early identification. As a consequence treatment is not empiric but rather tailored to the organism infecting the patient, hence preventing multiple drug resistance developing and ultimately saving a life through rational drug use. / WHSLYP2016

by Lau Yick Ki. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1987. / Includes bibliographies.