A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburq, in fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 1996. / An apparatus to measure residue curves and the associated VLE data was designed. The apparatus was required to measure this data quickly, easily, cheaply and reasonably accurately. The Acetone, Benzene and Chloroform and the Acetone, Methanol and Benzene ternary liquid systems were measured to test the accuracy of the apparatus. In both cases, the results obtained correlated reasonably well with those predicted by theory using published data. [Abbreviated Abstract. Open document to view full version] / AC2017

Orientador: Saul Gonçalves D'Avila / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Campinas / Made available in DSpace on 2018-09-11T20:49:22Z (GMT). No. of bitstreams: 1 Krahenbuhl_MariaAlvina_M.pdf: 3725977 bytes, checksum: 38538289dacd93804946d945b2946e7c (MD5) Previous issue date: 1987 / Resumo: Neste trabalho são discutidos três aspectos do tratamento termodinâmico de dados de Equilíbrio Líquido-Vapor (ELV), que compõem a base da metodologia da determinação experimental de dados P-T-x-y para aplicação em projeto e simulação de processos: (1) Teste de Consistência Termodinâmica através da integração da Equação da Coexistência enfatizando os sistemas tendo ácido carboxílico; (2) Determinação experimental do ELV num ebuliômetro de recirculação, focalizando as misturas etanol-água e água-ácido acético na faixa de 19,998 a 133,322 kPa (150 à 1000 mmHg), preenchendo lacunas existentes, na literatura; (3) Correlação dos dados P-T-x-y usando seis modelos de coeficientes de atividade da fase líquida. / Abstract: This work discusses three aspects of the thermodynamic treatment of Vapor-Liquid Equilibria (VLE) data, which forms the core of the methodology of the experimental determination of P-T-x-y data for process design purpose:(1)thermodynamic Consistency Test by means of the integration of the Coexistence Equation, with special emphasis on systems containing carboxylic acid; (2) Experimental determination of VLE in a circulatin still apparatus,1 focusing the mixtures ethanol-water and water-acetic acid in the range 19,998 to 133,322 kPa (150 to 1000 mmHg), filling the existing gap in the literature; (3) Correlation of P-T-x-y data using six liquid-phase activity coefficients models. / Mestrado / Mestre em Engenharia Química

A presente tese de doutorado apresenta, pela primeira vez, a produção de estruturas tridimensionais (3D) de nanotubos de carbono (NTC), nomeadas esponjas de NTC, por deposição química de vapor (CVD) empregando o catalisador sólido nanoestruturado em pó (magnésio ferrita - MgFe2O4). As nanopartículas de MgFe2O4 foram produzidas por síntese de combustão em solução (SCS). Esta técnica permite a produção de pós nanoestruturados de baixo custo e elevada qualidade. Sabe-se que as nanopartículas de MgFe2O4 são excelentes catalisadores para a produção de nanotubos de carbono (NTC). Propriedades como área superficial, inversão do espinélio, tamanho de cristalito, grau de aglomeração e sua correlação com as forças de van der Waals foram examinadas nesta tese. A síntese de arquiteturas 3D de NTC continua sendo um dos desafios mais importantes na nanotecnologia. Estes sistemas possuem um grande potencial para supercapacitores, eletrodos catalíticos, músculos artificiais e em aplicações ambientais. Nesta tese, realizou-se o estudo detalhado da influência dos parâmetros de síntese por CVD na obtenção de esponjas de NTC. Parâmetros como tempo de síntese, temperatura, fluxo de hidrogênio, fluxo de hexano e quantidade de catalisador empregado foram avaliados. A rota de síntese desenvolvida dispensa sistemas de aerossol, agentes dopantes e catalisadores comerciais, reduzindo significativamente o custo e a complexidade da síntese de esponjas de NTC, facilitando a reprodutibilidade. Ao final do estudo foi possível obter-se uma rota de síntese padrão com os seguintes parâmetros: 0,100 g de quantidade de catalisador, 100 cm3/min de fluxo de Hidrogênio, 40 minutos de tempo de síntese, 850º C de temperatura, 150 cm3/min de fluxo de Hexano e 300 cm3/min de fluxo de Argônio. Partindo deste padrão foi possível obter esponjas de NTC com tamanho de 8,78 mm de altura x 14 cm de comprimento x 9,9 mm de largura com cerca de 0,770 g. As esponjas sintetizadas apresentaram resistência à deformação mecânica e a temperatura, além de alta absorção de fluidos apolares (cerca de 1600 % em peso de gasolina e óleo diesel em apenas um minuto de contato). Estas propriedades indicam que as esponjas produzidas são fortes candidatas para aplicações ambientais. / This PhD thesis presents, for the first time, the production of carbon nanotube (CNT) sponges by chemical vapor deposition (CVD) employing solid nanopowered catalyst (magnesium-ferrite - MgFe2O4). Nanoparticles of MgFe2O4 were produced by solution combustion synthesis (SCS). This technique allows the production of low cost and high quality nanostructured powders. It is known that nanoparticles of MgFe2O4 are excellent catalysts for the production of carbon nanotubes. Properties such as surface area, spinel inversion, crystallite size, degree of agglomeration and its correlation with van der Waals forces were examined in this thesis. The synthesis of CNT 3D architectures remains one of the most important challenges in nanotechnology nowadays. These systems have high potential for application as supercapacitors, catalytic electrodes, artificial muscles and environmental applications. In this thesis, it was carried out a detailed study of the influence of the CVD synthesis parameters in the obtaining of CNT 3D Sponges. Parameters such as synthesis duration time, temperature, hydrogen flow, hexane flow and amount of catalyst employed were evaluated. The developed synthesis route dispenses aerosol systems, dopant agents and commercial catalysts, reducing significantly the synthesis cost and complexity, in a synthesis of easy reproducibility. At the end of the study, t was possible to obtain a standard synthesis route with the following parameters: 0.100 g of catalyst amount, 100 cm 3 / min of Hydrogen flow, 40 minutes of synthesis time, 850 ° C of temperature, 150 cm 3 / min of Hexane flow and 300 cm 3 / min of Argon flow. From this standard it was possible to was possible to obtain 3D CNT sponges with a size of 8.78 mm in height x 14 cm in length x 9.9 mm thick, weighting about 0.770 g. Macrostructure resistance to mechanical deformation and temperature, besides the high absorption of non-polar fluids (about 1600 wt. % to gasoline and diesel oil in only one minute of contact between them), indicate that the produced sponge is a strong candidate for environmental applications.

Orientador: Pedro Magalhães Sobrinho / Banca: Eliana Vieira Canettieri / Banca: Christian Jeremi Coronado Rodriguez / Resumo:As tecnologias tradicionais utilizadas na geração de vácuo para fabricação de aço são ejetores a vapor, bombas de vácuo de anel líquido e sistemas combinados entre esses dois. O sistema de ejetores de vapor tem uma capacidade de gerar um vácuo médio de 101 kPa (1 atm) a 0,1 Pa (0,01 mbar), as bombas de anel líquido chegam a apenas 3 kPa (30 mbar) e as bombas secas abrangem a faixa de 101 kPa (1 atm) até 67 Pa (0,67 mbar), faixa necessária para a aplicação em metalurgia secundária e é o limite desta tecnologia. Neste trabalho foi realizado estudo de caso no setor industrial que utiliza a geração de vácuo à ejetores a vapor superaquecidos a 250°C e 1,2 MPa (12 kgf/cm2) de pressão. O vácuo é necessário para a remoção de gases indesejáveis na composição do aço, como Nitrogênio, Oxigênio, Hidrogênio e Enxofre que causam fragilidades na estrutura cristalina. Atualmente têm surgido inovações tecnológicos para geração de vácuo para aplicações em VD (desgaseificação à vácuo), vácuos até 67 Pa (0,67 mbar) e para VOD (descarburação) para vácuos de 8-20 kPa (80-200mbar). Uma dessas inovações é a combinação de bombas mecânicas secas formando três estágios de vácuo, juntando várias tecnologias, sendo a primeira e segunda com rotor Roots e a terceira com rotor parafuso. Neste estudo o objetivo foi o de mensurar os rendimentos reais oferecidos pelo sistema de ejetores a vapor, juntamente com o rendimento da Caldeira em comparação com a nova tecnologia de bomba seca em aplicações siderúrgicas, apresentaremos as vantagens, desvantagens e custo benefício para a substituição do sistema de geração de vácuo. Representando uma redução de 92,7 % no consumo energético e 81,4% de redução dos custos operacionais / Abstract: Traditional technologies used to generate vacuum for steelmaking are steam ejectors, liquid ring vacuum pumps and systems combined of them. The steam ejector system has a capacity to generate a medium vacuum 101 kPa (1 atm) a 0,1 Pa (0,01 mbar), the liquid ring pumps only reach 3 kPa (30 mbar) and dried pump cover the range of 101 kPa (1 atm) até 67 Pa (0,67 mbar), band required for use in secondary metallurgy and is the limit of this technology. In this work was realized a case study in the industrial sector that uses the vacuum generation through steam ejectors superheated at 250 ° C and 1,2 MPa (12 kgf/cm2). The vacuum is needed for removal of undesirable gases in the composition of the steel as nitrogen, oxygen, hydrogen and sulfur which causes weakness in the crystalline structure. Currently there have been technological innovations for vacuum generation in applications in VD (vacuum degassing), vacuums until to 67 Pa (0,67 mbar) and VOD (decarburization) for vacuums of 8-20 kPa (80-200 mbar). One of these innovations is mechanical pumps dried formed by three-stage vacuum, joining various technologies, the first and second rotor roots and the third screw rotor. In this study the objective was to measure the real returns offered by the steam ejector system, along with the performance of the boiler compared to the new dry pump technology in steel making industry, will present the advantages, disadvantages and cost effective to replace the vacuum generating system. Representing a 92,7% reduction in energy consumption and 81,4 % reduction in operating costs / Mestre

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El presente trabajo muestra la forma de desarrollar la validación de uno de los pilares dentro del sistema de apoyo crítico en la industria farmacéutica: la Validación Prospectiva del Sistema Generador de Vapor Limpio, de tal manera que se establezca una evidencia documentada de que el proceso es capaz de cumplir en forma consistente y repetitiva las especificaciones establecidas. Se procedió a elaborar los protocolos en donde se definen los objetivos específicos de las evaluaciones a efectuar, las responsabilidades de cada una de las áreas involucradas; se establecieron variables de interés a monitorear, incluyendo el plan de monitoreo respectivo, además de incluir los criterios de aceptación que luego se compararon con los resultados esperados. Posteriormente se desarrollo el proceso de validación propiamente dicho, en el cuál se realizó una evaluación del proceso y se hicieron pruebas de que todos los componentes del sistema funcionan según lo especificado. Se sometió a prueba todos los controles de operación normal, verificación: del sistema generador, del sistema de control, de alarmas, de bomba, y de niveles de agua. Se hizo la calificación de desempeño, para la cuál se analizaron el perfil de pureza: control físico-químico (pH, conductividad, sustancias oxidables y sólidos totales) y control microbiológico (prueba de endotoxinas y carga microbiana) del condensado de vapor en el punto de uso por 30 días. Con los resultados obtenidos se concluye que el vapor producido por el generador de vapor limpio en una industria farmacéutica local es apto para su uso. -- Palabras Claves: Validación, Sistema, Generador, Vapor, Pureza. / -- The present work shows the form to develop the validation of one of the pillars within the system of critical support in the pharmaceutical industry: the Prospective Validation of the Generating Clean Steam System, in order to establish documentary evidence that the process is able to fulfill in consistent and repetitive form the established specifications. The protocols were elaborated in which the specific objectives of the evaluations, the responsibilities of each of the involved areas are defined to carry out; interest variables to monitor were established including the respective plan of monitoring; besides to sit includes the acceptance criterias which will be compared with the expected results afterwards. Then, the validation process itself was developed, in which an evaluation of the process was made and all the components of the system were tested to check whether they work according to the specifications or not. All the controls of normal operation were checked, verification: of the generating system, of the control system, alarms, pump, and water levels. The qualification of performance was made, for which analyzed the purity profile was analyzed: physical-chemistry control (pH, conductivity, rusty substances and total solid) and microbiological control (test of endotoxins and microbial load) of the condensed steam in the point of use by 30 days. With the obtained results we conclude that the steam produced by the clean steam generator in a local pharmaceutical industry is suitable for its use. -- Key Words: Validation, System, Generator, Steam, Purity. / Tesis

Process development of halide transport chemical vapor deposited (HTCVD) ZnS:Mn thin film has been studied. To this end, electrical characterization of HTCVD ZnS:Mn electroluminescent devices has been used. Process optimization focused on a simple design of experiment (DOE) with brightness as the major response. Deposition parameters such as HCl and H���S gas flow rates, ZnS and Mn source temperatures and substrate temperature were studied. A substrate temperature of 550��C gives the brightest devices. ZnS source temperature and H���S gas flow rate are insignificant parameters according to the statistical analysis. However HCl gas flow rate and Mn source temperature show strong interaction. It is proposed that the incorporation of Cl into the ZnS:Mn film causes the interaction. A Cl defect is also consistent with anomalous electrical behavior observed in the devices. Cl defects are thought to precipitate at the grain boundaries of the initial growth interface, then diffuse (or migrate) along the grain boundaries and possibly into the bulk crystal. This defect will easily form negative charge leading to asymmetric space charge in the bulk of the phosphor. Since the defects are believed to originate from the nucleation of Cl at high grain boundary density, one potential solution is to remove the Cl source as the grains begin to grow and only later expose the film to Cl. While film growth without HCl present at the beginning of deposition leads to brighter films, it is a sub-optimal solution. Part of the ZnS host does not have luminescent centers. It is believed other processing solutions need to be realized to make the HTCVD system viable. / Graduation date: 1999

Graduation date: 1995

The ability to produce potable water economically is the primary purpose of seawater desalination research. Reverse osmosis (RO) and multi-stage flash (MSF) cost more than potable water produced from fresh water resources. As an alternative to RO and MSF, this research investigates a high-efficiency mechanical vapor-compression distillation system that employs an improved water flow arrangement. The incoming salt concentration was 0.15% salt for brackish water and 3.5% salt for seawater, whereas the outgoing salt concentration was 1.5% and 7%, respectively. Distillation was performed at 439 K (331oF) and 722 kPa (105 psia) for both brackish water feed and seawater feed. Water costs of the various conditions were calculated for brackish water and seawater feeds using optimum conditions considered as 25 and 20 stages, respectively. For brackish water at a temperature difference of 0.96 K (1.73oF), the energy requirement is 2.0 kWh/m3 (7.53 kWh/kgal). At this condition, the estimated water cost is $0.39/m3 ($1.48/kgal) achieved with 10,000,000 gal/day distillate, 30-year bond, 5% interest rate, and $0.05/kWh electricity. For seawater at a temperature difference of 0.44 K (0.80oF), the energy requirement is 3.97 kWh/m3 (15.0 kWh/kgal) and the estimated water cost is $0.61/m3 ($2.31/kgal). Greater efficiency of the vapor compression system is achieved by connecting multiple evaporators in series, rather than the traditional parallel arrangement. The efficiency results from the gradual increase of salinity in each stage of the series arrangement in comparison to parallel. Calculations using various temperature differences between boiling brine and condensing steam show the series arrangement has the greatest improvement at lower temperature differences. The following table shows the improvement of a series flow arrangement compared to parallel: ?T (K) Improvement (%)*1.111 2.222 3.333 15.21 10.80 8.37 * Incoming salt concentration: 3.5% Outgoing salt concentration: 7% Temperature: 450 K (350oF) Pressure: 928 kPa (120 psig) Stages: 4