Reproduction de : Thèse doctorat : Chimie : Metz : 2004. / Titre provenant de l'écran-titre. Notes bibliographiques.

Orientador: Sergio Santos Mühlen / Dissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-18T19:10:57Z (GMT). No. of bitstreams: 1 Hernandes_MarceloRocha_M.pdf: 3294457 bytes, checksum: d5c6210ad1c775f02c1a394d65ab908c (MD5) Previous issue date: 2011 / Resumo: A questão da partida a frio de motores movidos a Diesel ainda é um problema que não foi apropriadamente resolvido e se torna particularmente crítico em face da tendência de redução de níveis de emissões de poluentes a baixas temperaturas e da taxa de compressão do motor visando redução do consumo de combustível. Embora esteja claro que existem alguns fatores-chave que levam a um apropriado processo de partida a frio, sua relevância e relações não são claramente compreendidas. Assim, os esforços para a otimização do processo de partida a frio são principalmente baseados em procedimentos de tentativa e erro em câmaras climáticas a baixas temperaturas, com sérias limitações em termos de confiabilidade da medição em algumas condições, baixa repetibilidade e altos custos com experimentos. O objetivo deste trabalho é estudar os componentes auxiliares de partida a frio dos motores a Diesel com o intuito de adquirir conhecimento sobre este tema para aplicação em propulsores, de maneira que estes possam ser utilizados em regiões com temperaturas negativas com desempenho confiável. Os componentes estudados serão apresentados, bem como sua aplicação e importância na tarefa de proporcionar as condições adequadas à partida a frio do motor. Além disso, uma visão geral será dada em relação à contribuição que estes componentes trazem na redução de emissões de poluentes e consumo de combustível / Abstract: Cold start in Diesel engines is a problem which has not yet been properly solved and becomes particularly critical with the current trend to reduce the emission levels at low temperatures and engine compression ratio addressed to fuel consumption decrease. Although it is clear that there are some key factors whose control leads to a proper cold start process, their individual relevance and relations are not clearly understood. Thereby, the efforts on optimization of the cold start process are mainly based on a trial-and-error procedure in climatic chambers at low ambient temperature, with serious limitations in terms of measurement reliability, low repeatability and high experiments costs. The objective of this work is to study cold start auxiliary components of Diesel engines in order to acquire knowledge on this topic for application in engines in a way that they can be used in regions with low temperatures with reliable performance. The components studied will be presented, as well as its application and importance of providing appropriate conditions to engine cold start. In addition, an overview will be given on the contribution that these components are going to bring in the reduction of emissions and fuel consumption / Mestrado / Eletrônica / Mestre em Engenharia Automobilistica

Thesis (M.S.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 54.

No description available.

The overall objective of this thesis was to develop field deployable instrumentation for the selective, sensitive determination of additives in diesel fuels using flow injection with chemiluminescence detection. The target analytes were the detergent dodecylamine and the lubricity additive P655. Chapter One describes the types of additives that are used in fully formulated diesel fuels in order to improve performance and outlines the need for robust analytical methods to be able to detect their presence / absences in fuels at the point of distribution, i.e. at the petrol pump. Flow injection (FI), and chemiluminescence (CL) are described as suitable techniques for sample preparation and detection respectively. The application of FI-CL for the quantitative determination of various analytes is reviewed, with the focus on real sample matrices. Finally the technique of solid phase extraction is discussed as a means of selective analyte preconcentration / matrix removal prior to FI-CL detection Chapter Two describes the development and optimisation (both univariate and simplex) of an FI-CL method for the determination of dodecylamine in acetonitrile / water mixtures using the catalytic effect of amines on the peroxyoxalate / sulphorhodamine 101 CL reaction. The linear range for dodecylamine was 0 - 50 mg Lˉ¹ with a detection limit of 190 µg Lˉ¹ and RSDs typically < 4 %. The effect of indigenous diesel compounds on the CL response is also investigated. Chapter Three investigates the applicability of the method developed in Chapter Two to determine dodecylamine in diesel fuels. Solid phase extraction was needed prior to analysis by FI-CL. The development of a solid phase extraction that is compatible with the FI-CL system is detailed. GC-NPD and GC-MS analysis are used in order to validate the solid phase extraction procedure. A range of diesel fuels have been spiked with an additive package containing dodecylamine and have been analysed off-line using FI-CL. Recoveries for all diesel fuels analysed were < 72 % and all fuels could by identified from the corresponding base fuel. Chapter Four describes the design and construction of a fully automated on-line solid phase extraction flow injection chemiluminescence analyser for the determination of dodecylamine in diesel fuel. Details of the automation and programming using LabVIEW are described. Results obtained using the automated on-line system are compared with results obtained using off-line SPE with FI-CL detection from Chapter Three. Recoveries for all fuels except SNV were < 71 %, and all fuels except SNV could be positively identified from the corresponding base fuels. No significant differences were found between the on-line and off-line results (within 95 % confidence limits). Chapter Five investigates the feasibility of determining the lubricity additive P655 in diesel fuel using FI-CL. The optimisation and development of a method using the competing reactions of periodate with alcohols and periodate with the CL oxidation reaction with pyrogallol is discussed, and the development of a solid phase extraction procedure for the extraction of P655 from an organic matrix is described. The limit of detection for P655 using SPE without preconcentration was 860 mg Lˉ¹ and was linear in the range 0 - 10000 mg Lˉ¹ (R² = 0.9965).

Thesis (M. E.)--University of New South Wales, 2003. / Also available online.

Thesis (M.S.)--Ohio State University, 1968. / Includes bibliographical references (leaves 37-39).

Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 176-178).

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 157-162).

Thesis (M.S.)--University of Wisconsin--Madison, 1985. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 95-97).