959 resultados para Lubricating oils


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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Includes bibliography

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Pós-graduação em Engenharia Mecânica - FEIS

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The lubricant oil used in engines of internal combustion must be, periodically, changed. Its mainly function in the engines is to reduce the friction between the pieces, but its presence also promotes the cleanness and the refrigeration of the equipment. These attributions, at the end of some cycles of operation, make the oil to be dirty, that is, full of contaminating substances such as water, gasoline, diesel, additives, oxidized hydro-carbons and rests of metals, not being recommended, therefore, its discarding in the environment. Thus, all the used lubricant oil that leaves the automobiles engine has been thrust, waiting for a solution. The pollution generated by the discarding of a ton of used oil per day in the soil or in the rivers is equivalent to a domestic sewer of 40 thousand of people. The indiscriminate burning of the used lubricant oil generates significant emissions of metallic oxides, besides other toxic gases, like the dioxin and sulphur oxides. In this context, the mean objective of this essay was to effectuate the rerrefine of the used lubricant oil, aiming the increase of its life cycle and consequently contributing for the reduction of the environmental pollution. According to the used process, it was possible to get a rerrefine oil, of good quality, which physicistchemistries properties are in compliance with the norms of NBR and ASTM

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Mode of access: Internet.

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Beginning with 1971 ed. published under title: Multicylinder test sequencs for evaluating automotive engine oils.

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"November 15, 1989."--Letter of transmittal.

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The heavy part of the oil can be used for numerous purposes, e.g. to obtain lubricating oils. In this context, many researchers have been studying alternatives such separation of crude oil components, among which may be mentioned molecular distillation. Molecular distillation is a forced evaporation technique different from other conventional processes in the literature. This process can be classified as a special distillation case under high vacuum with pressures that reach extremely low ranges of the order of 0.1 Pascal. The evaporation and condensation surfaces must have a distance from each other of the magnitude order of mean free path of the evaporated molecules, that is, molecules evaporated easily reach the condenser, because they find a route without obstacles, what is desirable. Thus, the main contribution of this work is the simulation of the falling-film molecular distillation for crude oil mixtures. The crude oil was characterized using UniSim® Design and R430 Aspen HYSYS® V8.5. The results of this characterization were performed in spreadsheets of Microsoft® Excel®, calculations of the physicochemical properties of the waste of an oil sample, i.e., thermodynamic and transport. Based on this estimated properties and boundary conditions suggested by the literature, equations of temperature and concentration profiles were resolved through the implicit finite difference method using the programming language Visual Basic® (VBA) for Excel®. The result of the temperature profile showed consistent with the reproduced by literature, having in their initial values a slight distortion as a result of the nature of the studied oil is lighter than the literature, since the results of the concentration profiles were effective allowing realize that the concentration of the more volatile decreases and of the less volatile increases due to the length of the evaporator. According to the transport phenomena present in the process, the velocity profile tends to increase to a peak and then decreases, and the film thickness decreases, both as a function of the evaporator length. It is concluded that the simulation code in Visual Basic® language (VBA) is a final product of the work that allows application to molecular distillation of petroleum and other similar mixtures.

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Three different lubricating greases and their bleed and base oils were compared in terms of film thickness in a ball-on-disc test rig through optical interferometry. The theoretical values calculated according to Hamrock's equation are in close agreement with the base oil film thickness measurements, which validates the selected experimental methodology. The grease and bleed oil film thickness under fully flooded lubrication conditions presented quite similar behaviour and levels. Therefore, the grease film thickness under full film conditions might be predicted using their bleed oil properties, namely the viscosity and pressure-viscosity coefficient. The base and bleed oil lubricant parameter LP are proportional to the measured film thickness. A relationship between grease and the corresponding bleed oil film thickness was evidenced.

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Natural rubber/isora fibre composites were cured at various temperatures. The solvent swelling characteristics of natural rubber composites containing both untreated and alkali treated fibres were investigated in aromatic and aliphatic solvents like toluene, and n-hexane. The diffusion experiments were conducted by the sorption gravimetric method. The restrictions on elastomer swelling exerted by isora fibre as well as the anisotropy of swelling of the composite have been confirmed by this study. Composite cured at 100°C shows the lowest percentage swelling. The uptake of aromatic solvent is higher than that of aliphatic solvent for the composites cured at all temperatures. The effect of fibre loading on the swelling behaviour of the composite was also investigated in oils like petrol, diesel, lubricating oil etc. The % swelling index and swelling coefficient of the composite were found to decrease with increase in fibre loading. This is due to the increased hindrance exerted by the fibres at higher fibre loadings and also due to the good fibre-rubber interactions. Maximum uptake of solvent was observed with petrol followed by diesel and then lubricating oil. The presence of bonding agent in the composites restrict the swelling considerably due to the strong interfacial adhesion. At a fixed fibre loading, the alkali treated fibre composite showed lower percentage swelling compared to the untreated one.