The modernized world is over-consuming low-cost energy sources that strongly contributes to pollution and environmental stress. As a consequence, the interest for environmentally friendly alternatives has increased immensely. One such alternative is the use of solar energy and water as a raw material to produce biohydrogen through the process of photosynthetic water splitting. In this work, the relation between H2-production and photosynthesis in the green algae Chlamydomonas reinhardtii was studied with respect to three main aspects: the establishment of prolonged H2-production, the involvement of PSII in H2-production and the electron pathways associated with PSII during H2-production. For the first time, this work reveals that PSII plays a crucial role throughout the H2-producing phase in sulfur deprived C. reinhardtii. It further reveals that a wave-like fluorescence decay kinetic, before only seen in cyanobacteria, is observable during the H2-producing phase in sulfur deprived C. reinhardtii, reflecting the presence of cyclic electron flows also in green algae.

An existing encoder system was analyzed to determine why the system had failed. This encoder system was found to have slipped off the crankshaft, resulting in the need for a new encoder mount system. A new encoder mount was designed and installed on a Detroit Diesel 3-53 engine. The encoder mount was designed to ensure positive contact with the crankshaft while not allowing the mechanism to have the same type of failure that was determined. During the validation of the encoder, the push rod connected to the fuel injector rocker arm failed, preventing further validation of the system. The failure of the push rods is described.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / The use of fuels (from crude oil) in vehicles is responsible for one of the biggest environmental challenges; SO2 emission. As a result most countries regulate their sulfur emissions, with the goal of getting to the use of 10 ppm sulfur fuels. These stringent fuel sulfur content requirements have resulted in intensive research being directed at alternative desulfurization technologies which will ensure the treatment of fuels to acceptable sulfur levels. Extractive desulfurization using ionic liquids (IL) may be considered as one of the most promising of these technologies and is the subject of the study presented in this work. This study served two major purposes: (1) to investigate the capacity as well as key parameters which affect the extraction efficiency of the IL; 1-butyl-3-methylimidazolium octylsulfate as a solvent for deep extractive desulfurization of real Fluid Catalytic Cracking Unit (FCCU) diesel fuel samples collected from a typical South African Refinery, (2) to study/find suitable solvents for the regeneration of sulfur-loaded 1-butyl-3-methylimidazolium octylsulfate and the efficiency and effectiveness of the regenerated IL in the desulfurization of diesel fuel. 1-butyl-3-methylimidazolium octylsulfate was selected due to its properties i.e. good extractive ability for S-compounds and insolubility in fuel oils. A 22.1% sulfur removal was achieved in the desulfurization of FCCU feed stream diesel fuel, while 96% sulfur removal was achieved for FCCU product stream diesel fuel. These results show that the IL is more effective in the selective removal of sulfur (S) from FCCU diesel product than from FCCU feed stream, suggesting that fuel sulfur content and stream composition affects the extraction efficiency and effectiveness of the IL. Based on thermodynamic considerations, hexane was selected as the most suitable solvent for the re-extraction of sulfur from spent IL. Regenerated IL was used for desulfurization of diesel and achieved highest sulfur removal of 95% and the IL was regenerated up to four times without appreciable decrease in efficiency. The results obtained herein show that ILs are effective in the desulfurization of real diesel oil samples when the sulfur concentration is not very high. Further studies on the recoverability of ILs as well as their environmental impact need to be done to support findings in this study. / GR2016

Orientador: Délson Luiz Módolo / Banca: Vicente Luiz Scalon / Banca: Elson Avallone / Resumo: A reação de transesterificação de óleos vegetais com álcool etílico ou metílico dá origem a ésteres metílicos ou etílicos de ácidos graxos, conhecidos como biodiesel. Este apresenta propriedades próximas do óleo diesel mineral como o número de cetano, massa específica, poder calorífico e relação ar-combustível. Porém, problemas decorrentes de sua maior viscosidade resultam em uma pulverização deficiente pelos bicos injetores levando a uma combustão de qualidade inferior, e com isso, formação de depósitos indesejáveis no interior do motor, alterações nas propriedades do óleo lubrificante e na composição dos gases de escape. Frente a essa questão se faz necessário o estudo da utilização de um aditivo capaz de tornar as características do biodiesel mais adequadas à sua utilização em motores de ignição por compressão e também o acompanhamento das alterações na composição dos gases de escape. O aditivo estudado nesse trabalho foi o d-limoneno, um hidrocarboneto obtido como subproduto da citricultura, que foi adicionado ao óleo diesel à ser utilizado como combustível do conjunto moto-gerador utilizado nos ensaios. Neste sistema foram aplicadas diferentes cargas e coletados os dados relativos à emissão do motor. Resultados relevantes como a redução de material particulados foram observados mesmo com a adição de pequenas quantidades de d-limoneno / Abstract: The transesterification of vegetable oils with methanol or ethanol results in methyl esters or ethyl esters of fatty acid, known as biodiesel. This one presents similar features of diesel oil, such as cetane number, specific weight, heat of combustion and air-fuel ratio. However, arising problems from its higher viscosity leads to a poor spraying by the fuel injectors and so to a low-grade combustion, causing formation of undesirable deposits inside the engine, changes in the properties of the lubricating oil and in the composition of the exhaust gas. Owing to this issue, it is necessary to study an additive able to make biodiesel characteristics more appropriate to be used in compression ignition engines, as well as a monitoring of changes in exhaust gas composition. The chosen additive was d-limonene, a hydrocarbon obtained as a byproduct of citriculture, which was added to diesel fuel to be used as fuel for the motor-generator set used in the tests. Different loads were applied to this system and the engine emission data were collected. Relevant results such as the reduction of particulate material were observed even with small amounts of d-limonene added / Mestre

Thesis advisor: Dunwei Wang / Artificial photosynthesis is achieved by placing a semiconductor in water, where photoexcited charges generate a photovoltage at the surface of the semiconductor. However, solar to fuel efficiencies of earth abundant metal oxides and metal nitrides remain limited by their low photovoltages. Many different treatments have been used to improve the photovoltages of semiconductors, such as photocharging, surface regrowths, or the addition of heterogeneous catalysts. However, in these treatments, it remains unclear whether the enhanced photovoltage arises from improved kinetics or energetics. In many of the following studies, the surface kinetics of different semiconductors are measured in order to quantify how surface kinetics are related to the photovoltage of these materials. Different spectroscopic measurements are made along with detailed analysis of the Fermi level and quasi Fermi level in order to corroborate the kinetic data with energetic data. Together, this dissertation explores a multitude of methods and procedures that demonstrate how the photovoltage of semiconductors can be understood and manipulated for photoelectrochemial artificial photosynthesis. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Antes de transportar os derivados de petróleo por dutos, a sua corrosividade é verificada por meio do ensaio NACE TM-0172 ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). O referido ensaio, por basear-se na avaliação visual, não tem por objetivo a determinação da taxa de corrosão e nem a verificação do tipo de corrosão e, normalmente, os profissionais que o executam não têm conhecimento da influência das variáveis que interferem nos resultados do ensaio. Desta forma, o presente estudo teve como objetivos: verificar a influência de algumas variáveis (velocidade de agitação, geometria do corpo-deprova, temperatura, teor de água, tempo de ensaio e pH) nos resultados obtidos com o ensaio NACE TM-0172 (NACE, 2001), fazer avaliação quantitativa da taxa de corrosão por meio da determinação da perda de massa dos corpos-de-prova expostos ao meio, correlacionar os resultados da avaliação visual com a perda de massa, verificar se o ensaio, que é realizado em condições aeradas, simula adequadamente as condições internas dos dutos. Para condução do estudo, além do próprio ensaio NACE TM-0172 (NACE, 2001), foram realizados outros ensaios simples utilizando o aço-carbono COPANT 1020 na confecção dos corpos-de-prova metálicos. Com base em todos os ensaios realizados, foi possível fazer uma análise crítica do ensaio NACE TM-0172 (NACE, 2001) e justificar a adoção das diferentes condições de ensaio além de apresentar uma explicação para o mecanismo de corrosão do açocarbono na mistura derivado/água. / Before transporting distillate fuels by pipelines, their corrosive properties are verified by the NACE TM-0172 test ?Determining Corrosive Properties of Cargoes in Petroleum Product Pipelines? (NACE, 2001). This test, being based on a visual evaluation, has as its goal, neither the determination of the corrosion rate nor the verification of the corrosion type; the technicians usually do not know the influence of the variables that interfere in the test results. Thus, this study had as its goals: to verify the influence of some variables (stirring speed, coupon geometry, temperature, water content, test duration and pH of the water phase) in the results obtained with the NACE TM-0172 test (NACE, 2001), to make the quantitative evaluation of the corrosion rate by determination of the coupon mass loss exposed to this condition, to correlate the results of the visual evaluation with the mass loss, to verify if the test, which is made in aerated conditions, simulate properly the internal conditions of pipelines. To conduct the study, besides the NACE TM-0172 (NACE, 2001) test itself, other simple tests were made using the carbon steel COPANT 1020 to prepare the metallic coupons. Based on all the tests, it was possible to make a critical analysis of the NACE TM-0172 (NACE, 2001) test and (to) justify the adoption of different test conditions as well as there being the possibility of presenting an explanation for the mechanism of the carbon steel corrosion in the mixture distillate/water.

No description available.

Orientador: Ricardo Alan Verdú Ramos / Banca: João Batista Campos Silva / Banca: Jhon Jairo Ramirez Behainne / Resumo: Na produção de biodiesel em pequena escala são comumente empregados os decantadores para separar o glicerol do biodiesel após a reação química de transesterificação do óleo com um álcool e um catalisador. Na maioria das vezes, esse processo de separação é realizado de forma manual e subjetiva por um operador que está sujeito a erros de interpretação, podendo, com isso, aumentar o custo de produção e/ou comprometer a qualidade do combustível produzido. Neste trabalho é proposta uma metodologia para o desenvolvimento e teste de um sistema eletrônico micro controlado, capaz de distinguir as fases formadas após o processo de decantação por meio de um sensor de condutividade elétrica, o qual permite o acionamento de válvulas para controle automático do direcionamento do biodiesel e do glicerol para reservatórios distintos. Essa metodologia contém a técnica de desenvolvimento abrangendo modelagem, simulação computacional, seleção de materiais, usinagem, projeto eletrônico, calibração e obtenção das características do desempenho do sensor. O sistema é composto por um painel elétrico que permite observar características do processo, através de um visor de LCD, e permite alterar as configurações do micro controlador, através da comunicação USB do equipamento com um computador. O sistema se mostrou eficiente nos testes com o biodiesel e glicerol, em processos produtivos com óleo de soja refinado, sendo que o glicerol apresentou valor de condutividade superior ao biodiesel, conforme esperado / Abstract: In the production of biodiesel on a small scale decanters are commonly utilized to separate the glycerol from biodiesel produced after a chemical reaction of oil with some alcohol and a catalyst. In most cases, this separation process is done manually and subjectively by an operator that can make mistakes in interpretation, increasing the cost of production and/or compromising the quality of the fuel produced. This work presents a methodology for developing and testing of a micro controlled electronic system, capable of distinguishing the phases formed after the decanting process by means of an electrical conductivity sensor, which permits the actuation of valves in order to have an automatic control of the direction of biodiesel and glycerol for different reservoirs. This methodology contains the technical development including modeling, computer simulation, materials selection, manufacturing, electronic project, calibration and obtains the performance characteristics of the sensor. The system consists of an electrical panel, which allows to observe the process through features an LCD display and permits change the settings of microcontroller through the USB communication device with a computer. The system proved effective in tests with biodiesel and glycerol production processes with refined soybean oil, and glycerin showed conductivity value higher than biodiesel as expected / Mestre

The introduction of alternative fuels such as natural gas is likely to occur at an increasing rate. The dual-fuel concept allows these low cetane number fuels to be used in compression-ignition (CI, diesel) type engines. Most CI engine conversions have pre-mixed the alternative fuel with air in the intake manifold while retaining diesel injection into the cylinder for ignition. The advantage is that it is simple for practical adaptation; the disadvantage is that good substitution levels are only obtained at midload. A better solution is to inject both the alternative and diesel fuels directly into the cylinder. Here, the fuel in the end-zone is limited and the diesel, injected before the alternative, has only a conventional ignition delay. This improves the high-end performance. Modern, very high pressure diesel injectors have good turndown characteristics as well as better controllability. This improves low-end performance and hence offers an ideal platform for a dual-fuel system. Several systems already exist, mainly for large marine engines but also a few for smaller, truck-sized engines. For the latter, the key is to produce a combined injector to handle both fuels which has the smallest diameter possible so that installation is readily achieved. There exists the potential for much improvement. A combined gas/diesel injection system based on small, high pressure common-rail injectors has been tested for fluid characteristics. Spray properties have been examined experimentally in a test rig and modelled using CFD. The CFD package Fluent was used to model the direct-injection of natural gas and diesel oil simultaneously into an engine. These models were initially calibrated using high-speed photographic visualisation of the jets. Both shadowgraph and schlieren techniques were employed to identify the gas jet itself as well as mixing regions within the flow. Different orientations and staging of the jets with respect to each other were simulated. Salient features of the two fuel jets were studied to optimise the design of a dual-fuel injector for CI engines. Analysis of the fuel-air mixture strength during the injection allowed the ignition delay to be estimated and thus the best staging of the jets to be determined.

<p>High temperature filtration in combustion and gasification processes is a highly interdisciplinary field. Thus, particle technology in general has to be supported by elements of physics, chemistry, thermodynamics and heat and mass transfer processes. This topic can be addressed in many ways, phenomenological, based on the up stream processes (i.e. dust/aerosol formation and characterisation) or apparatus oriented.</p><p>The efficiency of the thermochemical conversion process and the subsequent emission control are major important areas in the development of environmentally sound and sustainable technology. Both are highly important for combustion and gasification plant design, operation and economy. </p><p>This thesis is divided into four parts:</p><p>I. High temperature cleaning in combustion processes.</p><p>II. Design evaluations of the Panel Bed Filter technology.</p><p>III. Biomass gasification</p><p>IV. High temperature cleaning of biomass gasification product gas</p><p>The first part validates the filter performance through field experiments on a full scale filter element employed to a biomass combustion process and relates the results to state of the art within comparable technologies (i.e. based on surface filtration). The derived field experience led to new incentives in the search for a simplified design featuring increased capacity. Thus, enabling both high efficiency and simplified production and maintenance. A thorough examination of design fundamentals leading to the development of a new filter geometry is presented.</p><p>It is evident that the up-stream process has significant influence upon the operation conditions of a filter unit. This has lead to a detailed investigation of some selected aspects related to the thermochemical conversion. Furthermore, the influence of fuel characteristics upon conversion and product gas quality is discussed.</p><p>The last part discusses the quality of biomass gasification product gas and requirements put upon the utilisation of this gas in turbines, diesel engines or other high temperature applications. Filtration experiments conducted on product gas derived from wood gasification are reported and discussed.</p>