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M.Sc. (Chemistry) / The preparatIon of fine powders having large surface are as was carried out using the Hot Kerosene Drying Method (H.K.D.). In this method an emulsion containing An aqueous solution of a sought after cation is emulsified along with kerosene having a high boiling point (200+ C). The emulsion is then added to a given amount of the kerosene at a predetermined temperature above the boiling point of water, in a drop-wise fusion, during which the water con concerned in the emulsion rapidly evaporates resulting in the solid accumulating on the bottom of the flask. The powder is then separable from the kerosene using conventional means. Tungsten and iron-containing powders were each, made according to this method. The preliminary preparations were carried out with tungsten containing emulsions. In an attempt to produce an emulsion having the smallest internal phase diameter, w/o iron-containing emulsions prepared using different concentrations of the emulsifying agents and various kerosene-water ratios, were photographed microscopically under high magnification. Sedimentation rates and the presence of phase separation of the emulsions were recorded. In this manner an optimum emulsion with regard to particle size and stability was found. This emulsion composition was employed to prepare a series of emulsions with varying concentratiOns of the iron sulphate solution. Powders were prepared from these emulsions by subjecting them to the ".K.D. procedure. In another series of experiments the effect of the kerosene bath temperature on the quality of the poWders was studied. The surface areas of the solids were determined by using a dynamic method, and these could be directly related to the particle size of the powders for purposes of comparison...

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 99-100).

The goals of this research were first to examine flame quenching in tubing smaller than the quench diameter, and then to place lower size limits on microcombustor and microreactor systems by studying a catalytic microcombustor burning propane. In the first set of experiments, flame quenching was examined as a function of wall temperature for various hydrocarbon fuels. This was accomplished by creating a wall temperature profile along a tube, allowing a flame to propagate down the tube, and measuring the temperature of the tube wall coincident with the flame front. This wall quench temperature was plotted as a function of both the equivalence ratio and tube diameter. Fuels tested included propane, hexane, kerosene and diesel. Results showed that quench diameter was reduced by elevating the wall temperature and that the quench temperature increased for increasing mixture flow velocities. Flames were produced in tubes down to 0.8 mm in diameter. In the second set of experiments, a catalyst was used in combination with fuel preheating to obtain a self-sustaining combustion reaction in a chamber approximately 0.25 mm³ in size. Propane was used in this experiment. Results demonstrated that a stable self-sustaining reaction can be obtained in the microscale regime and that reaction temperatures are on the order of 900°C. This research not only aided in the characterization of hydrocarbon combustion in small diameter channels but also showed promise for development of microcombustor systems. / Graduation date: 2002

[pt] No presente trabalho foram desenvolvidos métodos analíticos para a determinação seletiva de azaarenos básicos. Extração em fase sólida (SPE, do inglês solid phase extraction) em combinação com cromatografia líquida de alta eficiência com detector de fluorescência (HPLC-FD, do inglês high performance liquid chromatography with fluorescence detector) foram utilizados como um método sensível para a determinação de seis azaarenos básicos (7,8-benzoquinolina - 78BQ, 7,9-dimetilbenzo[c]acridina - 79DMBA, 9-amino-1,2,3,4-tetrahidroacridina - 9ATHA, 9-metilacridina - 9MA, acridina - A, e dibenzo[a,j]acridina - DBA) em amostras de querosene de aviação (QAV) e querosene comercial. O procedimento de extração foi realizado em uma única etapa usando um cartucho de ácido propilsulfônico. Para HPLC, foram utilizados separação em fase reversa (C18) e um programa de detecção com os comprimentos de onda ótimos de excitação e de emissão. Um gradiente de eluição com acetonitrila (ACN) e tampão fosfato (pH 6,5) permitiu uma separação rápida e eficiente dos azaarenos em menos de 15 min. Os valores de LOD e LOQ, baseados na razão sinal-ruído de 3:1 e 10:1, respectivamente, ficaram entre 0,0013 e 0,021 e entre 0,0044 e 0,072 ng injetados. As curvas analíticas mostraram comportamento linear na faixa de trabalho estudada, LOQ a 250 ug L(-1), (r2 > 0,99). Para uma amostra de QAV fortificada com 6,0 ug L(-1), as recuperações foram de 92 a 107%, exceto para a 9ATHA, que apresentou um valor de recuperação menor (68%). Finalmente, o método proposto foi aplicado para a quantificação dos seis azaarenos básicos em uma amostra de querosene doméstico e em três amostras de QAV. A presença de 78BQ e DBA foi confirmada nas amostras de QAV. Em seguida, estudos para o desenvolvimento de métodos por eletroforese capilar foram avaliados para a quantificação dos azaarenos básicos em QAV. Em cromatografia eletrocinética capilar micelar, as condições selecionadas para a separação dos analitos, na fase preliminar de estudo, foram: tampão borato 20 mmol L(-1) contendo 40 mmol L(-1) de SDS, 20% de metanol e 2 mol L(-1) de uréia, pH 9,5; condições instrumentais: 30 kV, 30 °C e 10 s de injeção hidrodinâmica por pressão de 50 mbar. No caso de eletroforese capilar de zona (CZE), as condições selecionadas para a separação e a préconcentração dos analitos em linha foram: tampão fosfato 50 mmol L-1 contendo 25% de ACN, pH 2,65; condições instrumentais: 25 kV, 25 °C e 150 s de injeção hidrodinâmica por pressão de 50 mbar; amostra dissolvida em tampão fosfato 1 mmol L(-1) contendo 20% de ACN. Um capilar de sílica fundida com 64,5 cm de comprimento (56 cm efetivos), 50 (u)m de diâmetro interno e 150 (u)m de caminho óptico foi utilizado. Os valores de LOD e LOQ para o método CZE ficaram entre 0,68 e 3,2 e entre 1,1 e 7,7 (u)g L(-1), respectivamente. Os resultados obtidos até o momento indicam, com perspectivas positivas, que é possível aplicar CZE com pré-concentração em linha para a determinação dos azaarenos básicos em QAV. Entretanto, um estudo mais detalhado para melhorar a resolução e a sensibilidade e diminuir o tempo de análise ainda se faz necessário. Além disso, o procedimento de extração dos analitos da amostra de QAV deve ser ajustado para, além de proporcionar bons resultados de recuperação, ser compatível com o método de análise desenvolvido. Finalmente, um método alternativo foi desenvolvido, usando a aquisição de espectros de fluorescência por varredura sincronizada e a análise dos dados por mínimos quadrados parciais (PLS) para a determinação simultânea dos mesmos seis azaarenos em QAV. Foram utilizadas 40 amostras sintéticas, contendo os seis analitos em estudo, na faixa de 10 a 100 (u)g L(-1) em Metanol:HCl 0,01 mol L(-1). Os espectros de varredura sincronizada foram obtidos com (delta)(lambda) = 30, 120 e 150 nm. Na construção dos modelos de regressão PLS foram empregadas 20 amostras para calibração e 20 para a previsão (et / [en] In this work, analytical methods were developed for the selective determination of basic azaarenes. Solid phase extraction (SPE) in combination with high performance liquid chromatography with fluorescence detection (HPLCFD) has been used for the sensitive method determination of six basic azaarenes (7,8-benzoquinoline - 78BQ, 7,9-dimethylbenz[c]acridine - 79DMBA, 9-amino- 1,2,3,4-tetrahydroacridine - 9ATHA, 9-methylacridine - 9MA, acridine - A, and dibenz[a,j]acridine - DBA) in jet fuel samples. The extraction process was performed in a single step using a propyl sulfonic acid cartridge (PRS). The HPLC system consisted of C18 column with a selected detection program of optimum excitation ((lambda) exc) and emission ((lambda)em) wavelengths. A gradient elution with ACN and phosphate buffer (pH 6.5) allowed an efficient and fast separation of the azaarenes within 15 min. The LOD and LOQ values, based on signal-to-noise ratio 3:1 and 10:1, respectively, were between 0.0013 and 0.021 and from 0.0044 to 0.072 ng per injection. The calibration curves showed linear behavior in range from LOQ to 250 mg L(-1) (r(2) > 0.99). For the spiked concentration of 6.0 (u)g L(-1), the recoveries were from 92 to 107% for jet fuel samples, except for 9ATHA, which presented a lower recovery value (68%). Finally, the proposed method was applied to the quantification of those six basic azaarenes in a commercial kerosene sample and in three jet fuel samples. The presence of 78BQ and DBA was confirmed in the jet fuel samples. Capillary electrophoresis methods were evaluated for the quantification of the basic azaarenes in jet fuel samples. In MECC, the best conditions for the separation of the analytes, in the preliminary phase of study, have been: 20 mmol L(-1) borate buffer with 25% of methanol and 40 mmol L(-1) SDS (pH 9.5) as the background solution; instrumental conditions: 30 kV, 30 °C and hydrodynamic injection (50 mbar) for 10 s. In CZE, the best conditions for the separation of the analytes have been: 50 mmol L(-1) phosphate buffer with 25 % of acetonitrile (pH 2.65) as the background solution; instrumental conditions: 25 kV, 25 °C and hydrodynamic injection (50 mbar) for 150 s; sample solvent: 1 mmol L(-1) phosphate buffer with 20 % of acetonitrile. A fused-silica capillary of 50 mm ID x 64.5 cm (56 cm effective length) x 150 mm path length has been used. The LOD and LOQ values were between 0.68 and 3.2 and from 1.1 to 7.7 (u)g L(-1), respectively. The previous results showed positive perspectives to apply CZE with on-line pre-concentration for the determination of the basic azaarenes in jet fuel. However, a more detailed study to improve the resolution and sensitivity and to reduce the analysis time is still necessary. Moreover, the procedure of the analytes extraction from the kerosene sample must be adjusted for providing good results of recovery and to be compatible with the developed method of analysis. Finally, an alternative method was developed, using fluorescence spectra acquisition by synchronous scan and partial least square regression (PLS), for determination of the same basic azaarenes. 40 synthetic mixtures were used in the range of 10 to 100 (u)g L(-1). The synchronous scan spectra were obtained using (lambda)(delta) = 30,120 and 150 nm. In the PLS models, 20 samples were used for calibration and 20 for test. The clean-up procedure was adapted from the HPLC-FD method employing Methanol:HCl 0,01 mol L(-1) as the final solvent of the extraction. The extracts were analyzed by HPLC and the results were used as reference values. The LOD and LOQ values, calculated from the net analytical signal (NAS), were between 0.045 and 2.0 and from 0.15 to 6.6 (u)g L(-1), respectively. The relative standard errors of prediction (%RSEP) were from 3.0 to 10% for the sample test set. For the spiked jet fuel sample the %RSEP were between 4.9 and 11% for four of the six studied analytes, since it

L'un des objectifs de l'industrie aéronautique est, aujourd'hui, de fournir une flotte aérienne plus efficace et plus respectueuse de l'environnement. C'est dans ce contexte qu'une nouvelle génération d'avions dit plus « électrifiés » (MEA, More Electrified Aircraft) est développée. Dans cette optique, l'utilisation multifonctionnelle d'une pile à combustible multifonctionnelle dans l'aéronef permettrait de réduire et de simplifier le nombre de systèmes embarqués. Toutefois l'intégration d'une pile à combustible à l'intérieur d'un avion pose un problème majeur :l'approvisionnement en hydrogène. Pour surmonter cet obstacle, la génération d'hydrogène à bord de l'avion semble être une solution appropriée étant donné la possibilité de produire le combustible à partir du kérosène JET-A1. Les technologies de reformage classique d'hydrocarbures comme le steam reforming, l'oxydation partielle et le reformage autothermique ne sont pas réalisables à bord d'un avion. C'est pourquoi un nouveau concept de génération d'hydrogène, à bord de l'aéronef, a été développé dans ce travail : La déshydrogénation partielle (PdH, PartialDeshydrogenation) du kérozène. Le kérosène modifié par la déshydrogénation est alors réinjecté dans le pool de carburant. L'objectif d'Airbus concernant ses futurs avions est d'embarquer un système de production d'hydrogène avec une capacité volumétrique de 80 gL-1 et une production d'hydrogène de 7.5 kg h-1 pour alimenter une pile à combustible d'une puissance de 125 KW. Dans ce projet, la cible à atteindre pour l'unité de production est : 1000 NLH2kgcat-1h-1 d'hydrogène avec une pureté supérieure à 98 % et une durée de vie de 100 heures.Ce travail s'intéresse à la faisabilité du concept PDh à partir d'études théoriques et expérimentales. Les études théoriques ont pour but de répondre aux questions fondamentales telles que la possibilité de déshydrogéner un hydrocarbure à basse température, la nature des espèces hydrocarbonées dans le carburant et sa pression de vapeur, la température idéale assurant le meilleur compromis entre la production d'hydrogène et la formation de coke qui désactive le catalyseur. Les études expérimentales ont été conduites à la fois à partir de catalyseurs d'hydrogénation-déshydrogénation commerciaux et à partir de catalyseurs optimisés pour la réaction PDh, préparés en laboratoire. A la lumière de ce travail, le matériau présentant les meilleures performances est un catalyseur bimétallique à base de platine et d'étain supporté sur l'alumine-g. Les résultats des différentes études expérimentales sont positifs et montrent qu'à basse température (350 °C) et P = 10 bar, la production d'hydrogène est de 435.3 NLH2kgcat-1h-1 avec une pureté supérieure à 98 % et avec une durée de vie extrapolée à 21.7 h. A haute température (450 °C) et P = 10 bar la pureté du gaz chute à 36.3% mais la production d'hydrogène de 1157.05 NLH2kgcat-1h-1, pour une durée de vie de21.7 h, est plus élevée que la cible fixée. Les courtes durées de vie observées dans les deux conditions d'expérience sont attribuées au dépôt de coke sur le catalyseur et à la présence de soufre au sein du kérosène.Toutefois ces travaux ont permis de montrer la pertinence et la faisabilité du concept PDh même si des recherches complémentaires demeurent nécessaires pour une application embarquée. / The aviation industry is in support to bring greener and more efficient aircraft into the skies, as new generation of more electrified aircraft (MEA) are being developed. One technology on this roadmap is to implement a fuel cell on-board an aircraft, which has a “multi-functional” approach and can reduce many on-board systems & simplify operations for an aircraft. However, the implementation of a PEMFC on-board has one drawback – the supply of hydrogen. On-board hydrogen generation poses certain advantageous as there is already a hydrogen-rich material on all aircrafts, aviation fuel Kerosene Jet A-1. However, conventional fuel reforming technologies such as steam reforming, partial oxidation (thermal or catalytic) and autothermal reforming are not feasible for aircraft application. Therefore, a novel hydrogen generation concept was developed in this work that is geared towards on-board operation called Partial Dehydrogenation (PDh). For future aircraft, Airbus is aiming to have a hydrogen delivery system with a volumetric capacity of ca. 80 g L--1, delivering 7.5 kg hr-1 of hydrogen to power a 125 kWe PEMFC on-board. However to nurture this new hydrogen generation concept, milestones were set to focus the development which is limited to 1000 NLH2 kgcat-1 hr-1 with >98 % pure hydrogen with a lifetime of 100 hours. This work investigates the feasibility of the concept of PDh, from theoretical studies to experimental investigations, paving the way to appraise the discoveries so far for aircraft applicability. Theoretical studies were aimed at answering fundamental questions such as the potential of low temperature dehydrogenation, hydrogen availability from Kerosene Jet A-1, hydrocarbon species within the fuel, the vapour pressure of such a complex fuel, and the ideal temperature range to operate for hydrogen liberation with limit coke formation. Experimental investigations were performed with commercial hydrogenation-dehydrogenation catalysts, as well as experimental catalysts designed for the PDh process. In which the best catalyst found thus far is a bimetallic Tin-Platinum catalyst on ã-alumina. The overall findings of the experimental investigation were positive and can be summed up in two different stages of development. At low temperature of 350 °C at 10 bar, hydrogen produced was at 435.3 NLH2 kgcat-1 hr-1, hydrogen purity exceeding 98 % were obtained but with an extrapolated lifetime of 21.7 hours. At higher temperature of 450 °C at 10 bar, hydrogen purity dropped to 36.3 % but exceeded the activity goal with 1157.05 NLH2 kgcat-1 hr-1, however, the lifetime was still extrapolated to be in the region of 21.7 hours. Coke deposition and the influence of sulphur can be explained by the short lifetime found within the experiments. Nevertheless, the novel hydrogen production concept PDh has been showed to be possible, but further research and development is required to achieve on-board applicability.

Les réglementations sur les NOx émis par les avions sont sévères. Les techniques les réduisant ont des inconvénients. Pour les supprimer, deux pistes sont explorées. La première modifie l'architecture des chambres de combustion et les stabilise par une cavité. La seconde dope le kérosène au ralenti.Peu d'information est disponible sur les mécanismes de stabilisation et sur la structure de flamme des Trapped Vortex Combustor. Pour y remédier, un TVC est construit. L'étude de l'écoulement à froid ainsi que l'étude temporellement résolue de la flamme, mettent en avant les éléments stabilisateurs et déstabilisateurs. L'impact de la structure de flamme sur les émissions est évalué.La seconde partie porte sur l'effet de l'ajout d'hydrogène et de gaz de reformeur dans une chambre conventionnelle. Malgré une légère augmentation des émissions de NOx, l'ajout de composés hydrogénés réduit fortement les émissions de CO, augmente la stabilité et réduit la limite d'extinction pauvre. / Environmental standards on aircraff NOx emissions are strict. Technics for reducing them have drawbacks. Two options are explored in this study to supress them. The first one is to fundamentally change the current combustion chamber architecture, to stabilize them by a cavity, the second, to dope fuel at idle.Little information on the mechanisms of stabilization and on the flame structure on Trapped Vortex Combustor is available. To remedy this, a TVC is built. The stabilizing ans destabilizing parameters are pointed out by the cold flow investigation and the temporally resolved study of the combustion. The impact of the flame structure on pollutant emissions is also considered.The second part of this stud, deals with the addition of pure hydrogen an of reformer gas in a conventional combustuion chamber. Despite a slight increase in NOx emissions, the addition of hydrogenated compounds reduces drastically CO emissions, increases the flame stability and reduces the LBO limit.

It is widely accepted that climate change is a very serious environmental concern. Levels of carbon dioxide (CO2) and other emissions in the global atmosphere have increased substantially since the industrial revolution and now increasing faster than ever before. There is a thought that this has already led to dangerous warming in the Earth’s atmosphere and relevant changes around. Emissions legislations are going to be stringent as the years will pass. Hydro carbon fuel cost is also increasing substantially; more over this is non- renewable source of energy. There is an urgent need for novel combustor technologies for reducing emission as well as exploring alternative renewable fuels without effecting combustor performance. Development of novel combustors needs comprehensive understanding of conventional combustors. The design and development of gas turbine combustors is a crucial but uncertain part of an engine development process. At present, the design process relies upon a wealth of experimental data and correlations. Some major engine manufacturers have addressed the above problem by developing computer programs based on tests and empirical data to assist combustor designers, but such programs are proprietary. There is a need of developing design methodologies for combustors which would lead to substantial contribution to knowledge in field of combustors. Developed design methodologies would be useful for researchers for preliminary design assessments of a gas turbine combustor. In this study, step by step design methodologies of dual annular radial and axial combustor, triple annular combustor and reverse flow combustor have been developed. Design methodologies developed could be used to carry out preliminary design along with performance analysis for conventional combustion chambers. In this study the author has also proposed and undertaken preliminary studies of some novel combustor concepts. A novel concept of a dilution zone less combustor has been proposed in this study. According to this concept dilution air would be introduced through nozzle guide vanes to provide an optimum temperature traverse for turbine blades. Preliminary study on novel dilution zone less combustor predicts that the length of this combustor would be shorter compared to conventional case, resulting in reduced weight, fuel burn and vibrations. Reduced fuel burn eventually leads to lower emissions. Another novel concept of combustor with hydrogen synthesis from kerosene reformation has been proposed and a preliminary studies has been undertaken in this work. Addition of hydrogen as an additive in gas turbine combustor shows large benefits to the performance of gas turbine engines in addition to reduction in NOx levels. The novel combustor would have two stages, combustion of ~5% of the hydrocarbon fuel would occur in the first stage at higher equivalence ratios in the presence of a catalyst, which would eventually lead to the formation of hydrogen rich flue gases. In the subsequent stage the hydrogen rich flue gases from the first stage would act as an additive to combustion of the hydrocarbon fuel. It has been preliminary estimated that the mixture of the hydrocarbon fuel and air could subsequently be burned at much lower equivalence ratios than conventional cases, giving better temperature profiles, flame stability limits and lower NOx emissions. The effect of different geometrical parameters on the performance of vortex controlled hybrid diffuser has also been studied. It has been predicted that vortex chamber in vortex controlled hybrid diffuser does not play any role in altering the performance of diffuser. The overall contribution to knowledge of this study is development of combustor preliminary design methodologies with different variants. The other contribution to knowledge is related to novel combustors with a capability to produce low emissions. Study on novel combustor and diffuser has yielded application of two patent applications with several other publications which has resulted in a contribution to knowledge. A list of research articles, two patents, awards and achievements are presented in Appendix C.

Thesis (MScAgric)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Paraffin, also called kerosene is used by small-scale soya bean farmers in some parts of Africa as a pest repellent. The repellent action is claimed to be effective against parasites during seed germination and development of the seedlings. Seeds are immersed in commercial paraffin for a few seconds and sown in the soil immediately. This method raised some questions about possible negative effects on the seed after the imbibition process but also on humans and animals consuming the plants and seeds. Experiments were designed to investigate whether this practice would have negative effects on seed germination and vigour of the resulting seedlings of seven selected crop species. A trial was also carried out to test the effectiveness of paraffin as a pest repellent on canola in a field situation. The collected data were analyzed using STATISTICA, software version 11. Wherever the experiments showed significant interaction or differences within main factors, the means were separated making use of Fischer’s LSD post-hoc analysis at p = 0.05. The first series of experiments was done in the laboratory. It was carried out on seeds of seven crop species: canola (Brassica napus L.), common beans (Phaseolus vulgaris L.), ground nuts (Arachis hypogea L.), maize (Zea mays L.), soya bean (Glycine max L.), sunflower (Helianthus annuus L.) and wheat (Triticum aestivum L.). In the germination trial, seeds were subjected to a 7X5X4 factorial design treatment with factors Crop species (CS) (see above), Paraffin concentration (PC) (0, 25, 50, 75 and 100% of commercial paraffin diluted with distilled water) and Time of immersion (TOI) (1, 5, 10, and 30 minutes). Treatments were repeated four times. After immersion seeds were dried with water absorbent paper and immediately germinated in 90 mm diameter petri dishes containing two filter papers and 5 ml of distilled water. Germination tests included 10 seeds per replicate and were incubated at a constant temperature of 20°C under dark conditions in an incubator. Findings showed that canola, sunflower and soya bean are paraffin tolerant (>70 % germination), wheat and groundnuts are less tolerant (30% – 70% germination) and beans and maize are intolerant (< 30 % germination). The paraffin had a negative influence on the rate of germination but there were no statistically significant differences between the 25% to 100% paraffin concentrations. Measurements of the quantity of water and of paraffin absorbed were done after seeds of the seven crop species were immersed in 0, 25, 50, 75 and 100% paraffin concentrations for 30 minutes. Beans absorbed more water at 100% water and more paraffin at 25% paraffin than the other crop species. The paraffin uptake decreased with the increase of paraffin concentration while water uptake increased with the increase in water percentage. In both cases canola had the lowest uptake. Differential uptake of water and paraffin did not explain the results of the germination test. Seeds of the seven crop species immersed in different paraffin concentrations (0, 25, 50, 75 and 100%) for thirty minutes were dried and then soaked in distilled water for 20 hours. The electrical conductivity (EC) of the liquid was determined by means of an EC meter after 20 hours of soaking. This was done to investigate whether paraffin treatment influenced leaking of electrolytes, which would indicate damage to the cell membranes in the seed. Results showed that sunflower leaked more electrolytes than any other seed, while wheat and maize had lower electrolyte leakage than the other species. This showed that the negative effect of paraffin on the germination of some crop species was unlikely to be due to membrane damage because sunflower seeds that leaked most electrolytes had a high germination percentage while the maize and wheat seeds that leaked little electrolytes, had poor germination after paraffin treatments. The second experiment was conducted in a glasshouse. Seeds of the seven crop species were subjected to the same PC and TOI treatments as described in the germination experiment above but instead of being placed in an incubator to germinate, they were planted in 8cm x 8 cm plastic pots (10 seeds in each) in coarse sand in a glasshouse that was running at approximately 20ºC. The establishment of the seedlings was monitored daily in the glasshouse. The final percentage of establishment was calculated. Three weeks after planting, the seedlings were thinned to one plant per pot. The mean root and stem lengths as well as dry mass of the seedlings was recorded when the seedlings were thinned. The one plant per pot that was retained was harvested six weeks after establishment. Root and stem length and dry mass were determined. Establishment percentage and tolerance indices were calculated. Maize and beans showed the lowest establishment percentages and sunflower scored the highest establishment percentage after treatment with paraffin. The root and stem lengths of the crops were generally unaffected by paraffin treatments. In terms of dry mass paraffin had a significant negative effect on groundnut at three weeks but at six weeks no effect of paraffin on any of the vegetative growth parameters could be observed. The third experiment was run in the microscope laboratory. A test using a confocal and fluorescence microscope was carried out to determine if residues of paraffin could be found in germinating soya bean seeds and seedlings. Specimens collected from the germinating soya bean seed and seedlings were mounted on the fluorescent microscope and stained with a solution of 100 μg.ml-1 Nile Red and observed with LD Plan-Neofluar 60X/0.6. Results showed that paraffin did penetrate the soya bean seed and was translocated within the plant system (endodermis) as the plant grows. The concentrations of paraffin in the tissue were however quite low. The fourth experiment was run on the Langgewens Experimental Farm near Moorreesburg in the Western Cape Province. Forty blocks were spatially grouped into two separate groups. Twenty blocks received the five paraffin treatments replicated four times and the other twenty blocks received the five water treatments also replicated four times. Within each group the treatments were allocated randomly to the plots. The experimental design was a 2X5 Factorial experiment with factors Treatment liquid (distilled water and paraffin) and Time of immersion (0, 1, 5, 10 and 30 minutes) replicated four times. No pesticides were applied to the canola crop. Stand density, leaf area and dry mass were recorded at the first harvest at 12 weeks, and then dry mass was determined at 21weeks. Final yield was determined after 27 weeks when the plots were harvested by means of a combine plot harvester. The stand density, leaf area and dry mass were significantly increased by paraffin treatments at the time of the first harvest. After 21 weeks paraffin treatment had no significant effect on the dry mass production of the canola and the same was true of the final seed yield. . Even though there was no serious attack by pests, the little feeding damage that occurred in the water treated plots and not in the paraffin treated plots, indicate that paraffin may have a repellent effect. Paraffin had no negative effects whatsoever on the growth and yield of canola in this experiment. This study indicates that different crops react differently to seed treatment with paraffin. The results of the fourth experiment indicate that paraffin might be used as pest repellent on certain selected crops but more research is needed on the subject. / AFRIKAANSE OPSOMMING: Paraffien, ook genoem keroseen, word deur kleinskaalse boere in sekere dele van Afrika gebruik as ‘n pesafweermiddel. Dit word beweer dat die afweeraksie suksesvol is teen parasiete tydens saadontkieming en vroeë saailinggroei. Saad word in kommersiële paraffien gedoop vir ‘n paar sekondes en dan onmiddelik daarna geplant. Die metode skep vrae oor die moontlike negatiewe gevolge op die saad na die imbiberingsproses maar ook op mense en diere wat die plante en sade benut. Eksperimente is beplan om vas te stel of die praktyk negatiewe gevolge op die saadontkieming en groeikragtigheid van die daaropvolgende saailinge van sewe geselekteerde gewasspesies sal hê. ‘n Eksperiment is ook uitgevoer om die effektiwiteit van paraffien as pesafweermiddel op kanola in ‘n veldsituasie te toets. Die data wat ingesamel is is ontleed deur gebruik te maak van STATISTICA, sagteware, uitgawe 11. Waar betekenisvolle interaksies of verskille binne hooffaktore voorgekom het, is die gemiddeldes geskei deur middel van Fischer se LSD post-hoc ontleding by p = 0.05. Die eerste reeks eksperimente is uitgevoer in ‘n laboratorium. Dit is uitgevoer op sade van sewe gewasspesies naamlik . kanola (Brassica napus L.), gewone bone (Phaseolus vulgaris L.), grondbone (Arachis hypogea L.), mielies (Zea mays L.), sojabone (Glycine max L.), sonneblom (Helianthus annuus L.) en koring (Triticum aestivum L.). In die ontkiemingsproef is die sade onderwerp aan ‘n 7X5X4 ewekansige blokontwerp wat faktoriaal gerangskik is met faktore Gewasspesies (CS) (sien hierbo), Paraffien konsentrasie (PC) (0, 25, 50, 75 en 100% van kommersiële paraffien verdun met gedistilleerde water) en Tyd van indompeling (TOI) (1, 5, 10, en 30 minute). Behandelings is vier keer herhaal. Na indompeling is die sade met waterabsorberende papier gedroog en onmiddelik daarna in 90 mm deursneë petribakkies wat twee filtreerpapiere en 5 ml gedistilleerde water bevat het, ontkiem. Tien sade per petribakkie is gebruik en die petribakkies is geïnkubeer by ‘n konstante temperatuur van 20ºC in die donker in ‘n inkubasiekas. Resultate het getoon dat kanola, sonneblom en sojaboon bestand is teen paraffienbehandelings (>70% ontkieming), koring en grondboon is minder bestand (30-70% ontkieming) en mielies en gewone bone is sensitief vir paraffienbehandeling (<30% ontkieming). Die paraffien het oor die algemeen ‘n negatiewe effek op ontkiemingstempo gehad maar daar was geen statisties betekenisvolle verskille tussen die 25% en 100% paraffienbehandelings nie. Die hoeveelheid water en paraffien wat opgeneem is deur sade van die sewe gewasspesies nadat dit in paraffienkonsentrasies van 0, 25, 50, 75 en 100% ingedompel is vir 30 minute, is bepaal. Gewone bone het meer water by die 100% water behandeling en meer paraffien by die 25% paraffien behandeling opgeneem as die ander spesies. Die paraffienopname het afgeneem met toename in paraffienkonsentrasie terwyl wateropname toegeneem het met toenemende waterkonsentrasies. Beide in geval van wateropname en paraffienopname het kanola die minste water opgeneem. Differensiële opname van water en paraffien het nie die resultate van die ontkiemingstoets verklaar nie. Sade van die sewe gewasspesies is in verskillende paraffienkonsentrasies (0, 25, 50, 75 en 100%) gedompel vir 30 minute, gedroog en daarna in gedistilleerde water geweek vir 20 uur. Aan die einde van die 20 uur wekingsperiode is die elektriese konduktiwiteit (EC) van die wekingsvloeistof bepaal deur middel van ‘n EC meter. Dit is gedoen om vas te stel of paraffienbehandeling die uitlek van elektroliete vanuit die saad, wat ‘n aanduiding van beskadigde selmembrane van die saad kan wees, beïnvloed. Resultate het aangedui dat sonneblom die meeste elektroliete vrygestel het en koring en mielies die minste. Dit dui aan dat die negatiewe invloed van paraffien op sommige gewasspesies waarskynlik nie deur membraanbeskadiging veroorsaak is nie omdat sonneblom, wat die meeste elektroliete vrygestel het, die hoogste ontkiemingspersentasie na behandeling met praffien gehad het terwyl mielies en koring, wat die minste elektroliete vrygestel het, baie swak ontkieming gehad het na paraffienbehandeling. Die tweede eksperiment is in ‘n glashuis uitgevoer. Sade van die sewe gewasspesies is onderwerp aan dieselfde paraffienkonsentrasies en tye van indompeling as in die ontkiemingseksperiment hierbo maar in plaas van om die sade in ‘n inkubasiekas te ontkiem, is dit in 8 cm x 8 cm plastiekpotte wat gevul is met growwe sand geplant (10 sade per pot) in ‘n glashuis wat by ‘n konstante temperatuur van ongeveer 20ºC geloop het. Die vestiging van die saailinge in die glashuis is daagliks gemonitor en die finale persentasie van vestiging is bereken. Drie weke na plant is die saailinge uitgedun sodat een per pot oorgebly het. Die uitgedunde saailinge se gemiddelde wortel- en stamlengtes is bepaal asook die gemiddelde droëmassas. Die een plant wat per pot oorgebly het is na ses weke ge-oes en weer is wortel- en stamlengtes bepaal asook die droëmassas. Vestigingspersentasies en toleransie indekse is bereken. Mielies en gewone bone het die laagste vestigingspersentasies getoon en sonneblom die hoogste nadat die gewasse met paraffien behandel is. Die wortel- en stamlengtes van die gewasse was oor die algemeen nie deur paraffienbehandelings beïnvloed nie. In terme van droëmassa het paraffien ‘n negatiewe effek op grondbone gehad drie weke na plant maar na ses weke kon geen invloed van paraffienbehandelings op enige van die vegetatiewe groeiparameters waargeneem word nie. Die derde eksperiment is in ‘n mikroskooplaboratorium uitgevoer. ‘n Konfokale en fluoreserende mikroskoop is gebruik om te bepaal of oorblyfsels van paraffien gevind kan word in ontkiemende sojaboonsade en saailinge. Monsters wat geneem is van die ontkiemende sojaboonsade saailinge is gemonteer op die fluoreserende mikroskoop en gekleur met ‘n oplossing van 100 μg.ml-1 Nile Red oplossing en ge-evalueer met LD Plan-Neofluar 60X/0.6. Resultate het getoon dat paraffien wel die sojaboonsaad kon infiltreer en dat dit ook in die saailinge se endodermis vervoer kon word en opspoorbaar was. Die konsentrasies van paraffien in die weefsel was egter laag. Die vierde eksperiment is uitgevoer op die Langgewens Proefplaas naby Moorreesburg in die Wes-Kaap Provinsie. Veertig blokke is ruimtelik in twee groepe van twintig elk grangskik. Twintig blokke het die vyf paraffienbehandelings ontvang en twintig die vyf gedistilleerde waterbehandelings. Die behandelings is vier keer herhaal. Binne elke blok is die behandelings ewekansig toegeken aan persele. Die proefontwerp was ‘n 2X5 ewekansige geneste blokontwerp (split plot) wat faktoriaal gerangskik is met faktore Behandelingsvloeistof (gedistilleerde water en paraffien) en indompelingstyd (0, 1, 5, 10 and 30 minute). Geen insekdoders is op die kanola toegedien nie. Plantdigtheid, blaaroppervlakte en droëmassa is bepaal tydens die eerste monsterneming 12 weke na plant en daarna is slegs droëmassa bepaal na 21 weke. Na 27 weke is finale oesopbrengs bepaal deur die persele met ‘n perseelstroper te stroop. Plantdigtheid, blaaroppervlakte en droëmassa is betekenisvol verhoog deur paraffienbehandelings na 12 weke. Na 21 weke het die paraffienbehandelings egter geen betekenisvolle invloed op die droëmassa van die plante gehad nie en daar was ook nie verskille ten opsigte van finale oesopbrengs nie. Alhoewel daar nie ernstige insekskade waargeneem is nie, was dit tog duidelik dat die bietjie vreetskade wat in die waterbehandelings voorgekom het, nie in die paraffienbehandelings voorgekom het nie. Dit dui aan dat die paraffien moontlik ‘n afwerende invloed gehad het. Paraffien het geen negatiewe invloed enigsins gehad op die groei en produksie van kanola in hierdie eksperiment nie. Hierdie studie dui aan dat verskillende gewasse verskillend reageer op saadbehandeling met paraffien. Die resultate van die vierde eksperiment dui aan dat paraffien moontlik as ‘n pesafweermiddel op sekere geselekteerde gewasse gebruik kan word maar meer navorsing word benodig op die onderwerp.

Commercial aviation has demonstrated its ability to be a key driver of global socio-economic growth to this date. This growth, resulting from an ever increasing need for air-travel, has been observed to be environmentally unsustainable. Any technological enhancements to the upcoming fleet of aircraft or operational improvements have been overshadowed by this very demand for air-travel. Any further investigation into innovative concepts and optimisation approaches bring in trade-off difficulties due to limitations in current technology. This creates a constraint on design space exploration. The need to mitigate civil aviation’s environmental impact has necessitated this sector to expand its frontier and seek radical technologies. Among a range of other technologies, advanced biofuels for civil jet engines have been claimed to be one of the most promising solutions. “Techno-economic Environmental Risk Analysis (TERA) of Advanced Biofuels for Civil Aviation” is a study that contributes to knowledge through conception plus application of quantitative/ qualitative approaches to assess the technical viability, financial feasibility and environmental competence of 2nd and 3rd generation biojet fuels, through their application into the existing scenario of civil aviation, against that of the fossil-derived conventional jet fuel (Conv.Jet fuel). TERA of advanced biofuels aims to accomplish the aforementioned through a holistic, multi-disciplinary study entailing life cycle studies, carbon-foot printing, sustainability analysis, fuel chemistry, virtual studies comprising combustion thermodynamic, engine/aircraft performance and emission prediction, economic studies entailing biofuel price prediction and business case analysis as opposed to earlier studies. TERA of Advanced biofuels study entails development of elaborate life cycle models, ALCEmB (Assessment of Life Cycle Emissions of Biofuels) and ALCCoB (Assessment of Life Cycle Cost of Biofuels) to predict life cycle emissions and costs, respectively, of the advanced biofuels from the point of raw material generation to the point of finished product consumption (a “cradle-grave” approach). A virtual experiment, to assess the impact of the “performance” properties of the advanced biofuels on a representative twin-shaft turbofan/airframe combination, relative to that of Conv.Jet fuel, was also undertaken through numerical modelling and simulation.Evaluation through ALCEmB revealed that Camelina-SPK, Microalgae-SPK and Jatropha-SPK delivered 70%, 58% and 64% savings in life cycle emission, relative to Conv.Jet fuel. The Net Energy Ratio (NER) analysis indicates that current technology for the biofuel processing is energy efficient and technically feasible. An elaborate post-combustion gas property evaluation infers that the Bio-SPKs exhibit improved thermodynamic behaviour. This thermodynamic effect has a positive impact on mission-level fuel consumption which reflected as fuel savings in the range of 3 - 3.8% and, therefore, emission savings of 5.8-6.3% in CO2 and 7.1-8.3% in LTO NOx, relative to that of Jet-A1. An economic feasibility analysis which entails prediction of hypothetical biofuel price prediction and its impact on direct operating cost (DOC) of an aircraft which infers that Bio-SPKs, over a user-defined medium-range mission profile, costs an additional 95-100% in terms of aircraft DOC, relative to that operated with conventional Jet-fuel, within short (2020) and medium (2020). However, the advanced biofuels are able to exhibit financial competence from 2020 onwards, relative to that of Conv.Jet fuel. However, the Bio-SPKs exhibit this economic feasibility only against a backdrop of persistent Conv.Jet fuel price volatility and severe environmental taxation between the analysis periods (2020-2075).