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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Análise de falhas em tubos sem costura de aço St52 utilizados em motores diesel / Failure analysis in seamless pipes of St52 steel used in Diesel Engines

Belloto, Humberto Jesuino 19 August 2018 (has links)
Orientador: Paulo Roberto Mei / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-19T00:26:25Z (GMT). No. of bitstreams: 1 Belloto_HumbertoJesuino_M.pdf: 5308190 bytes, checksum: 1a5267190a7db08ed3b659370b64f95a (MD5) Previous issue date: 2011 / Resumo: O tubo de aço carbono com alto teor de manganês St52 (Norma DIN 1.0580) sem costura, com 8 mm de diâmetro externo e 3 mm de diâmetro interno, atualmente utilizado no sistema de combustível de motores eletrônicos a diesel com pressões de trabalho de até 1300 bar, apresentou problemas nos testes de durabilidade. O rompimento do tubo foi consequência das trincas internas originadas no processo de laminação, denominadas descontinuidades. O tubo de fabricação nacional, atualmente utilizado nos motores, foi comparado com um importado e os resultados dos testes encontrados determinaram qual deles teria maior vida à fadiga. São apresentados nesta dissertação o processo de fabricação do tubo com as suas vulnerabilidades, os testes de fadiga comparando as durabilidades dos tubos nacionais e importados, o efeito do processo de autofretagem e os ensaios metalográficos. Os resultados levaram a concluir que o tubo nacional não atende as solicitações de trabalho do motor e a solução imediata é a utilização do tubo importado. A recomendação para trabalhos futuros seria o estudo de melhoria no processo de laminação para diminuição do nível de descontinuidades internas tubos nacionais / Abstract: The carbon steel with high manganese in accordance with Din 1.0580 (St52) seamless 8 x 3 mm diameter has been used into fuel injection system of the electronic diesel king with pressure up to 1300 bar. This tube presented short life on durability tests due to inner cracks created during rolling process. The tube produced in Brazil and used nowadays in was compared with an imported one using a fatigue test. It is shown on this work the manufacturing tube process, the fatigue test applied to the national and imported tubes and the e effects. The results showed that the national tube does not meet the necessary requirements and the immediate solution is to use the imported one. It is recommended further used on the rolling process to reduce the internal roughness of the tubes produced in Brazil / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica
22

Estudo do tempo de mistura em tanques de diesel com o uso da fluidodinâmica computacional / Study of the mixing time in diesel storage vessels with the use of computational fluid dynamics

Àlvarez Castro, Helver Crispiniano, 1984- 19 August 2018 (has links)
Orientador: José Roberto Nunhez / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T04:07:53Z (GMT). No. of bitstreams: 1 AlvarezCastro_HelverCrispiniano_M.pdf: 3784043 bytes, checksum: bc88cbde39ba881df9a43aee4f3ba52c (MD5) Previous issue date: 2011 / Resumo: Este Trabalho tem por objetivo desenvolver um modelo de simulação dinâmica para um tanque de mistura de diesel de larga escala localizado na refinaria da Petrobras em Paulínia. O tanque é utilizado na área de produtos acabados médios da Petrobras. Neste sentido, o objetivo principal deste projeto inclui estimar o perfil de velocidade, tempo de mistura e a potência que o agitador requer para sua homogeneização, visando otimizar a operação destes tanques na Petrobras. O referido tanque de armazenamento e mistura de óleo diesel possui uma capacidade nominal de 24000 m3, o fluido possui densidade de 0,86 kg/ m3; O projeto do tanque esta baseado na norma API 650. Para a simulação utilizam-se técnicas baseadas em fluidodinâmica computacional (CFD). O método utilizado é o dos volumes finitos. Para atingir o objetivo proposto, utiliza-se o software comercial CFX versão 12.1. O software resolve numericamente as equações discretas de conservação de massa, momento e um modelo de turbulência associado ao modelo. O SST ( Shear Stress Transport Model ) é usado para se estimar a turbulência. A região do fluido é dividida em um grande número de volumes de controle, sendo construído um modelo de tanque equipado com uma entrada lateral de um misturador tipo naval . O modelo do impelidor foi fornecido pela PETROBRAS / Abstract: The aim of this work is the development of a computational model for large storage diesel mixing vessels. The tank studied is located at REPLAN (Refinery of Paulínia). This vessel is used for products with intermediate viscosity. It is intended to estimate velocity profiles, mixing time and energy consumption required for its homogenization, with a view to optimize its operation. This storage vessel has a nominal capacity of 24000 m3, the fluid has a specific mass of 0.86 kg/m3. The tank design follows the API 650 especifications. The model uses Computational Fluid Dynamics (CFD) techniques. It is based on the finite volume method. The commercial CFX 12.1 software was used to get the numerical data. This software solves numerically the discrete form of the mass, momentum and species conservation equations and the turbulence model associated to the general tank model. The SST ( shear Stress transport turbulence model ) is used to estimate the turbulence. The tank is divided into a great number of control volumes. The model of the vessel considers a lateral flow impeller (similar to a naval type impeller). The characteristics of the impeller was given by PETROBRAS / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química
23

Análise da influência de impelidores laterais no tempo de mistura em tanques de estocagem de diesel com o uso da fluidodinâmica computacional / Analysis of the influence of side-entry mixers on the mixing time in diesel storage vessels using computational fluid dynamics

Cabrales Navarro, Fredy Antonio 19 August 2018 (has links)
Orientadores: José Roberto Nunhez, Nicolas Spogis / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-19T06:34:09Z (GMT). No. of bitstreams: 1 CabralesNavarro_FredyAntonio_M.pdf: 2052593 bytes, checksum: d8d60c68b460ac2a2cd457e16a29e929 (MD5) Previous issue date: 2011 / Resumo: O processo de homogeneização de hidrocarbonetos em tanques de estocagem de grande escala equipados com impelidores de entrada lateral desempenha um papel importante na operação de uma refinaria, visto que a qualidade do produto final depende do desempenho deste processo. A Fluidodinâmica Computacional (CFD) é a técnica mais viável para avaliar e otimizar este processo, no qual o trabalho experimental é tecnicamente complicado e custoso. Neste trabalho, a técnica CFD é empregada para simular um tanque de estocagem de diesel a escala industrial com o uso do pacote comercial ANSYS CFX 13.0. A abordagem com múltiplos sistemas de referência (MFR) é empregada para modelar a movimentação do impelidor. Os efeitos turbulentos foram incorporados mediante o modelo de turbulência Shear Stress Transport (SST). Vários arranjos impelidor(es)/tanque obtidos variando o ângulo de deslocamento horizontal em relação à linha central do tanque são usados para avaliar a influência do número de impelidores e o seu posicionamento no desempenho do processo. Perfis hidrodinâmicos, consumos de potência, tempos de homogeneização e outros parâmetros relevantes para processos de mistura são utilizados para comparar os resultados. Baseando-se nos resultados das simulações, foi possível avaliar os diferentes cenários e determinar a condição mais apropriada para levar a cabo o processo. Considerando o consumo energético, a melhor configuração é utilizando um impelidor desviado 10 º e, levando em conta o tempo de homogeneização, o melhor arranjo é com três impelidores sem deslocamento. Adicionalmente, os prós e contras das alternativas foram discutidos e os resultados mais relevantes foram reportados / Abstract: The homogenization process of hydrocarbons in large scale storage tanks equipped with side-entry impellers plays an important role in a refinery operation, since the quality of the final products depends on the performance of this process. Computational Fluid Dynamics (CFD) is the most viable technique to evaluate and to optimize this process, as experimental work is technically complicated and expensive. In this work, the CFD technique is used to simulate an industrial diesel storage vessel using the commercial package ANSYS CFX 13.0. The Multiple Frames of Reference (MFR) approach is used to model the mixer movement. The turbulent effects are incorporated by means of the Shear Stress Transport (SST) turbulence model. Several impeller(s)/tank layouts obtained by varying the horizontal offset angle from the tank center line are used to assess the influence of the number of impellers and their positioning on the performance of the process. Hydrodynamic profiles, power consumptions, homogenization times and other relevant mixing parameters are also used to compare the results. Based on the computer simulation results, it was possible to evaluate the different scenarios and to determine the most appropriate conditions to carry out the process. Considering the power consumption, one impeller deviated 10° is the configuration with the best performance and, using three impellers without deviation is the arrangement that gives the shortest mixing time. In addition, the pros-and-cons of the other alternatives are discussed and the most relevant findings are reported / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química
24

Molecular Modeling of Ionic Liquids for Potential Applications in the Desulfurization of Diesel Fuel

Caudle, Miranda 10 December 2018 (has links)
No description available.
25

A Five-Zone Model for Direct Injection Diesel Combustion

Asay, Rich 19 September 2003 (has links) (PDF)
Recent imaging studies have provided a new conceptual model of the internal structure of direct injection diesel fuel jets as well as empirical correlations predicting jet development and structure. This information was used to create a diesel cycle simulation model using C language including compression, fuel injection and combustion, and expansion processes. Empirical relationships were used to create a new mixing-limited zero-dimensional model of the diesel combustion process. During fuel injection five zones were created to model the reacting fuel jet: 1) liquid phase fuel 2) vapor phase fuel 3) rich premixed products 4) diffusion flame sheath 5) surrounding bulk gas. Temperature and composition in each zone is calculated. Composition in combusting zones was calculated using an equilibrium model that includes 21 species. Sub models for ignition delay, premixed burn duration, heat release rate, and heat transfer were also included. Apparent heat release rate results of the model were compared with data from a constant volume combustion vessel and two single-cylinder direct injection diesel engines. The modeled heat release results included all basic features of diesel combustion. Expected trends were seen in the ignition delay and premixed burn model studies, but the model is not predictive. The rise in heat release rate due to the diffusion burn is over-predicted in all cases. The shape of the heat release rate for the constant volume chamber is well characterized by the model, as is the peak heat release rate. The shape produced for the diffusion burn in the engine cases is not correct. The injector in the combustion vessel has a single nozzle and greater distance to the wall reducing or eliminating wall effects and jet interaction effects. Interactions between jets and the use of a spray penetration correlation developed for non-reacting jets contribute to inaccuracies in the model.
26

Perfil dos HPA prioritários na exaustão de veículo a diesel, no combustível diesel utilizado durante os ensaios de emissão veicular e no óleo lubrificante do motor / HPA priority profile in diesel vehicle exhaust, in diesel fuel used during the emissions testing and in engine lubricant oil

Carolina Vieira de Souza 04 March 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As concentrações na exaustão e os fatores de emissão dos hidrocarbonetos policíclicos aromáticos (HPA) prioritários de um veículo a diesel e as suas respectivas concentrações no diesel usado durante os ensaios de emissão veicular foram determinados com a finalidade de estimar a contribuição dos HPA provenientes do combustível nas emissões. Os produtos da combustão foram coletados diretamente nas emissões brutas do escapamento, utilizando um sistema de amostragem a volume constante sem diluição dos gases da exaustão. Os HPA associados ao MP foram amostrados de forma estratificada, utilizando um impactador em cascata MOUDI e filtros de fibra de vidro como substratos, e os HPA em fase gasosa foram amostrados usando cartuchos de amberlite XAD-2. A concentração dos HPA no óleo lubrificante do motor também foi monitorada ao longo do tempo até a sua troca após 12.000 km de uso. Após a extração e tratamento das amostras, a identificação e quantificação dos HPA foram realizadas, utilizando cromatografia de fase gasosa acoplada à espectrometria de massas (CG-EM) com injetor de grande volume de vaporização com a temperatura programável (PTV-LVI). Cinco variáveis do PTV-LVI foram otimizadas, utilizando planejamento de experimentos, o que permitiu obter limites de detecção menores do que 2,0 g L-1. Somente 7 dos 16 HPA prioritários foram identificados na exaustão: NAP, ACY, ACE, FLU, FEN, FLT e PYR. Os ensaios de emissão veicular foram realizados com o veículo em modo estacionário, sem aplicação de carga e com baixa velocidade de rotação do motor (1500 rpm), utilizando um diesel com menor teor de enxofre (10 mg kg-1) e com 5% v/v de biodiesel. Esses fatores possivelmente contribuíram para reduzir as emissões dos outros 9 HPA a valores abaixo dos limites de detecção do método desenvolvido. Aproximadamente 80% da massa dos HPA totais associados ao MP estavam presentes em partículas com tamanho entre 1,0 m e 56 nm, e aproximadamente 4,5% estavam presentes em partículas menores do que 56 nm. Partículas menores que 2,5 m são facilmente inaladas e depositadas no trato respiratório e na região alveolar, justificando a preocupação com relação às emissões de HPA associados a partículas provenientes da exaustão veicular de motores a diesel. Somente 5 dos 7 HPA identificados na exaustão foram detectados no diesel: NAP, ACY, FLU, FEN e PYR. A razão entre os fatores de emissão (g L-1diesel) dos HPA na exaustão e suas respectivas concentrações do diesel (g L-1) variaram de 0,01 0,02 a 0,05 0,029, dependendo do HPA. Esses valores indicam que pelo menos 95 a 99% dos HPA identificados no diesel foram destruídos e/ou transformados em outros compostos durante a combustão, e/ou foram retidos no reservatório do óleo lubrificante. Por outro lado, os HPA que tiveram maiores concentrações no diesel também apresentaram maiores fatores de emissão, o que sugere que os HPA provenientes do diesel possuem uma contribuição significativa para as emissões dos HPA totais. O perfil dos HPA prioritários no óleo lubrificante mostrou-se semelhante ao perfil dos HPA no diesel e nas emissões totais, onde o NAP, FEN e PYR foram os HPA majoritários / A diesel vehicle exhaust concentrations and emission factors of priorities polycyclic aromatic hydrocarbons (PAHs) and their respective concentrations in the diesel fuel used during the vehicle emissions testing were determined in order to estimate the fuel PAHs contribution to vehicle emissions. Combustion products are collected directly from the raw vehicle exhaust using a constant volume sampling system that does not employ exhaust products dilution. The particle-phase PAHs were sampled in stratified way using a Micro-orifice Uniforme Deposite Impactor (MOUDI) and glass fiber filter as substrates and the gas-phase PAHs were sampled using Amberlite XAD-2 cartridge. The PAHs concentrations in the engine lubricant oil were also monitored over time until its change after 12,000 km of use. After sample extractions and treatments, the PAHs identification and quantification were performed using gas chromatography coupled with mass spectrometry (GC-MS) and programmable temperature vaporization large volume injection (PTV-LVI). Five PTV parameters were optimized using statistical design experiments, which allowed to be obtained detection limits below 2.0 g L-1. Only 7 of 16 priority PAH were identified in exhaustion: NAP, ACY, ACE, FLU, FEN, FLT and PYR. The vehicle emission tests were carried out with the vehicle in stationary mode, without load, low engine speed (1500 rpm), using diesel fuel with lower sulfur (10 mg kg-1) and 5% v/v biodiesel. These factors may have contributed to reduce the other 9 PAH emissions to values below the detection limits of the method developed. Approximately 80% of the PAHs total mass associated with the particulate matter were present in particle size between 1.0 m and 56 nm and approximately 4.5% were present in particles smaller than 56 nm. Particles smaller than 2.5 m are easily inhaled and deposited in the respiratory tract and in the alveolar region, justifying the concern about PAHs emissions associated with particles from vehicle exhaust diesel engine. Only 5 of the 7 PAHs identified in exhaust were detected in diesel fuel: NAP, ACY, FLU, PHE and PYR. The ratio between the PAHs emission factors in exhaust (g L-1 diesel) and their respective concentrations in diesel fuel (g L-1) ranged from 0.01 0.02 a 0.05 0.029, depending on the PAH. These values indicate that al least 95 to 99% of the PAH identified in diesel fuel were destroyed and/or converted into other compounds during the combustion, and/or been retained in lubricant oil reservoir. On the other hand, PAHs that had higher concentration in diesel also had higher exhaust emission factors, which suggests that the PAH from diesel have a mean contribution to total PAHs emissions. The PAH priority profile in lubricant oil was similar to PAH profile in diesel and in vehicle exhaust, where the NAP, FEN and PYR were the majorities PAHs
27

Perfil dos HPA prioritários na exaustão de veículo a diesel, no combustível diesel utilizado durante os ensaios de emissão veicular e no óleo lubrificante do motor / HPA priority profile in diesel vehicle exhaust, in diesel fuel used during the emissions testing and in engine lubricant oil

Carolina Vieira de Souza 04 March 2015 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As concentrações na exaustão e os fatores de emissão dos hidrocarbonetos policíclicos aromáticos (HPA) prioritários de um veículo a diesel e as suas respectivas concentrações no diesel usado durante os ensaios de emissão veicular foram determinados com a finalidade de estimar a contribuição dos HPA provenientes do combustível nas emissões. Os produtos da combustão foram coletados diretamente nas emissões brutas do escapamento, utilizando um sistema de amostragem a volume constante sem diluição dos gases da exaustão. Os HPA associados ao MP foram amostrados de forma estratificada, utilizando um impactador em cascata MOUDI e filtros de fibra de vidro como substratos, e os HPA em fase gasosa foram amostrados usando cartuchos de amberlite XAD-2. A concentração dos HPA no óleo lubrificante do motor também foi monitorada ao longo do tempo até a sua troca após 12.000 km de uso. Após a extração e tratamento das amostras, a identificação e quantificação dos HPA foram realizadas, utilizando cromatografia de fase gasosa acoplada à espectrometria de massas (CG-EM) com injetor de grande volume de vaporização com a temperatura programável (PTV-LVI). Cinco variáveis do PTV-LVI foram otimizadas, utilizando planejamento de experimentos, o que permitiu obter limites de detecção menores do que 2,0 g L-1. Somente 7 dos 16 HPA prioritários foram identificados na exaustão: NAP, ACY, ACE, FLU, FEN, FLT e PYR. Os ensaios de emissão veicular foram realizados com o veículo em modo estacionário, sem aplicação de carga e com baixa velocidade de rotação do motor (1500 rpm), utilizando um diesel com menor teor de enxofre (10 mg kg-1) e com 5% v/v de biodiesel. Esses fatores possivelmente contribuíram para reduzir as emissões dos outros 9 HPA a valores abaixo dos limites de detecção do método desenvolvido. Aproximadamente 80% da massa dos HPA totais associados ao MP estavam presentes em partículas com tamanho entre 1,0 m e 56 nm, e aproximadamente 4,5% estavam presentes em partículas menores do que 56 nm. Partículas menores que 2,5 m são facilmente inaladas e depositadas no trato respiratório e na região alveolar, justificando a preocupação com relação às emissões de HPA associados a partículas provenientes da exaustão veicular de motores a diesel. Somente 5 dos 7 HPA identificados na exaustão foram detectados no diesel: NAP, ACY, FLU, FEN e PYR. A razão entre os fatores de emissão (g L-1diesel) dos HPA na exaustão e suas respectivas concentrações do diesel (g L-1) variaram de 0,01 0,02 a 0,05 0,029, dependendo do HPA. Esses valores indicam que pelo menos 95 a 99% dos HPA identificados no diesel foram destruídos e/ou transformados em outros compostos durante a combustão, e/ou foram retidos no reservatório do óleo lubrificante. Por outro lado, os HPA que tiveram maiores concentrações no diesel também apresentaram maiores fatores de emissão, o que sugere que os HPA provenientes do diesel possuem uma contribuição significativa para as emissões dos HPA totais. O perfil dos HPA prioritários no óleo lubrificante mostrou-se semelhante ao perfil dos HPA no diesel e nas emissões totais, onde o NAP, FEN e PYR foram os HPA majoritários / A diesel vehicle exhaust concentrations and emission factors of priorities polycyclic aromatic hydrocarbons (PAHs) and their respective concentrations in the diesel fuel used during the vehicle emissions testing were determined in order to estimate the fuel PAHs contribution to vehicle emissions. Combustion products are collected directly from the raw vehicle exhaust using a constant volume sampling system that does not employ exhaust products dilution. The particle-phase PAHs were sampled in stratified way using a Micro-orifice Uniforme Deposite Impactor (MOUDI) and glass fiber filter as substrates and the gas-phase PAHs were sampled using Amberlite XAD-2 cartridge. The PAHs concentrations in the engine lubricant oil were also monitored over time until its change after 12,000 km of use. After sample extractions and treatments, the PAHs identification and quantification were performed using gas chromatography coupled with mass spectrometry (GC-MS) and programmable temperature vaporization large volume injection (PTV-LVI). Five PTV parameters were optimized using statistical design experiments, which allowed to be obtained detection limits below 2.0 g L-1. Only 7 of 16 priority PAH were identified in exhaustion: NAP, ACY, ACE, FLU, FEN, FLT and PYR. The vehicle emission tests were carried out with the vehicle in stationary mode, without load, low engine speed (1500 rpm), using diesel fuel with lower sulfur (10 mg kg-1) and 5% v/v biodiesel. These factors may have contributed to reduce the other 9 PAH emissions to values below the detection limits of the method developed. Approximately 80% of the PAHs total mass associated with the particulate matter were present in particle size between 1.0 m and 56 nm and approximately 4.5% were present in particles smaller than 56 nm. Particles smaller than 2.5 m are easily inhaled and deposited in the respiratory tract and in the alveolar region, justifying the concern about PAHs emissions associated with particles from vehicle exhaust diesel engine. Only 5 of the 7 PAHs identified in exhaust were detected in diesel fuel: NAP, ACY, FLU, PHE and PYR. The ratio between the PAHs emission factors in exhaust (g L-1 diesel) and their respective concentrations in diesel fuel (g L-1) ranged from 0.01 0.02 a 0.05 0.029, depending on the PAH. These values indicate that al least 95 to 99% of the PAH identified in diesel fuel were destroyed and/or converted into other compounds during the combustion, and/or been retained in lubricant oil reservoir. On the other hand, PAHs that had higher concentration in diesel also had higher exhaust emission factors, which suggests that the PAH from diesel have a mean contribution to total PAHs emissions. The PAH priority profile in lubricant oil was similar to PAH profile in diesel and in vehicle exhaust, where the NAP, FEN and PYR were the majorities PAHs
28

L'identification et quantification d'additifs dans les carburants et les lubrifiants par HPTLC-MS et techniques de dérivatisation / Identification and quantification of additives in fuels and lubricants by HPTLC-MS and derivatization techniques

Beaumesnil, Mathieu 24 October 2017 (has links)
Les compagnies pétrolières améliorent les propriétés de leurs produits et en particulier des carburants par l’ajout d’additifs. Un large choix de familles d’additifs est disponible, tels que les antioxydants ou les agents antidétonants. Dans ce travail, la chromatographie sur couche mince haute performance (HPTLC) a été utilisée pour quantifier certains additifs dans le gazole sans aucune préparation d’échantillon. L’HPTLC est une technique d’analyse qui est couramment utilisée afin d’analyser et quantifier des composés en mélange. Pour améliorer la détection des polymères et la qualité du signal, des méthodes de dérivatisation ont été utilisées. Afin de confirmer l’identification des composés et obtenir des informations structurales, un couplage direct entre l’HPTLC et la spectrométrie de masse a été développé. Les sources d’ionisation, comme la source DESI(Desorption Electrospray Ionization), la source DART (Direct Analysis in Real Time) et la source MALDI (Matrix Assisted Laser Desorption Ionization) ont été évaluées. Il est apparu que la source MALDI était la plus adaptée pour la désorption des additifs sur plaque HPTLC. Après des essais et optimisations sur différentes phases stationnaires, une méthode HPTLC-MALDI sur phase cellulose a été développée et a permis de détecter les détergents aux teneurs réelles dans le gazole. Parallèlement, l’HPTLC a été couplé pour la première fois à la source ASAP (Atmospheric Solids Analysis Probe). / Oil companies increase the quality of their products such as fuels by using additives. A large variety of additives can be used, such as antioxidants or antiknock agents. In this study, high performance thin layer chromatography (HPTLC) was used to quantify some additive in diesel fuel without sample preparation. HPTLC is an analytical technique used to characterize and quantify compounds in mixtures. To increase polymer detection and signal quality, derivatization methods were used.In order to confirm the analyte identification and to provide structural information, a method based on the direct coupling of HPTLC to mass spectrometry (MS) was developed. Ionization sources such as DESI (desorption electrospray ionization), DART (direct analysis in real time) and MALDI (matrix assisted laser desorption ionization) were evaluated. It appeared that MALDI was the most suitable source to efficiently desorb the additives on HPTLC plate. After several tests and optimizations on different stationary phases and ionization sources, a HPTLC-MALDI method was developed on cellulose and allowed to detect surfactant in diesel fuel at real concentration. At the same time, ASAP (atmospheric solids analysis probe) was coupled for the first time to HPTLC.
29

Desulphurization of diesel fuel using carbon-based metal oxide nanocomposites

Cherubala, Rusumba Bienvenu 04 1900 (has links)
M.Tech. (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / This thesis presents a slight on desulphurization process of the commercial diesel fuel using the carbon-based metal oxide nanocomposites such as graphene oxide, ZnO, rGO as a nano-adsorbent, activated carbon (PAC and AC) and charcoal Granular active carbon (GAC) to produce a fuel of less than 10 ppm sulphur content. Due to the high percentage of sulphur compounds in the fuel causing air pollution, acid rain and other problems related to combustion process. The synthesised of sorbents were achieved using incipient impregnation, microwaved-assisted and chemical exfoliation methods. The materials were characterized using Thermogrametric Analyzer (TGA), Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD), Brunauer, Emmett and Teller (BET). The examination effect of operating conditions on the adsorption capacity with DBT and Sulphur compounds adsorption, the isotherms and the adsorption kinetic models were evaluated. The experimental data for PAC and AC were well suited to Freundlich isotherm and pseudo second-order kinetic models. The results shown that the sulphur feed concentration, the space velocity and the functional groups of the adsorbents have a considerable effect on the adsorption. In addition, it was observed that the temperature in the range of 30 to 80oC has a significant effect on the adsorption of Sulphur compounds from diesel fuel using 20 wt.% of sorbents. The rGO substrate which contained abundant oxygen functional groups was confirmed to promote the dispersion metal oxide and increased the adsorption efficiency of sulphur compounds (H2S and SO2) by providing oxygen ions weakly bound to the sulphur molecules. For the desulfurization process by adsorption, PAC and AC exhibited a better affinity for 80% removal of sulphur compared to the GAC and GO. The effects of metal species such as zinc oxide (ZnO) and reduced graphite oxide (rGO) composite on the adsorption capacity of hydrogen sulphide (H2S) were investigated. It was found that depending on the copper load, the adsorption capacity of H2S increased up to 20 times compared to pure ZnO. To study the oxidation changes on copper and zinc oxides, crystallite analysis by XRD and chemical state analysis by XPS were performed.
30

ELECTRORHEOLOGY FOR ENERGY PRODUCTION AND CONSERVATION

Huang, Ke Colin January 2010 (has links)
Recently, based on the physics of viscosity, we developed a new technology, which utilizes electric or magnetic fields to change the rheology of complex fluids to reduce the viscosity, while keeping the temperature unchanged. The method is universal and applicable to all complex fluids with suspended particles of nano-meter, sub-micrometer, or micrometer size. Completely different from the traditional viscosity reduction method, raising the temperature, this technology is energy-efficient, as it only requires small amount of energy to aggregate the suspended particles. In this thesis, we will first discuss this new technology in detail, both in theory and practice. Then, we will report applications of our technology to energy science research. Presently, 80% of all energy sources are liquid fuels. The viscosity of liquid fuels plays an important role in energy production and energy conservation. With an electric field, we can reduce the viscosity of asphalt-based crude oil. This is important and useful for heavy crude oil and off-shore crude oil production and transportation. Especially, since there is no practical way to raise the temperature of crude oil inside the deepwater pipelines, our technology may play a key role in future off-shore crude oil production. Electrorehology can also be used to reduce the viscosity of refinery fuels, such as diesel fuel and gasoline. When we apply this technology to fuel injection, the fuel droplets in the fuel atomization become smaller, leading to faster combustion in the engine chambers. As the fuel efficiency of internal combustion engines depends on the combustion speed and timing, the fast combustion produces much higher fuel efficiency. Therefore, adding our technology on existing engines improves the engine efficiency significantly. A theoretical model for the engine combustion, which explains how fast combustion improves the engine efficiency, is also presented in the thesis. / Physics

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