The possibility of using waste vegetable oil from deep-frying processes as a fuel for long term use in diesel engines was investigated. Research was aimed at using existing technology in terms of engine design in order to utilize a maximum amount of waste vegetable oil as the energy source with a minimum of processing. A small swirl-chamber diesel engine was selected and used to run the 200-hour test recommended by the EMA for testing vegetable oil-based fuels. A blend of 20/80 (waste oil/diesel fuel) was tested as well as a 50/50 blend. BSFC data for both blends did not indicate any significant deterioration in engine performance during the 200 hour tests for ail the fuels tested. However, the 50/50 blend BSFC data had more spread than the data from the 20/80 or the diesel baseline test. This was attributed to variable amounts of deposits on the injector nozzle throughout this test Carbon deposits on all other parts of the combustion chamber were comparable for all the fuels tested. Wear of the engine parts was also comparable except for the piston rings. Piston ring wear was greater with diesel fuel and smaller when burning the 50/50 blend. This was attributed to a film of unburned fuel on the cylinder wall that improved lubrication. Lower -lubricating oil consumption was also attributed to this film. The alternate fuel blends completed the 200 hour EMA screening test and could be considered as possible candidates for long-term use in I.D.I, engines. / Applied Science, Faculty of / Graduate

No description available.

No description available.

No description available.

Hydrotreating processes play a vital role in petroleum refineries to meet the increasing demand of transportation fuels. The recent trends in processing of heavier crudes with higher sulphur contents and more stringent product specifications for cleaner transportation fuels, such as ultra-low sulphur diesel, are resulting in more severe operating conditions and higher hydrogen consumption of hydrotreating processes. In order to carry out any revamp or design projects for improving the performance and efficiency of hydrotreating units molecular kinetic models of hydrotreating reactions may be required to provide detailed and accurate information of the composition and properties of hydrotreating products. The overall hydrotreating process consisting of the hydrotreater, the separation system and the associated heat recovery system need to be modelled on a consistent basis of detailed characterisation of petroleum fractions and the interactions of these individual subsystems with each other and with the refinery hydrogen network handled simultaneously for overall process optimisation. A molecular pathways level model of diesel hydrotreating reactions using the molecular type and homologous series matrix is employed for prediction of detailed molecular level information of composition and properties of diesel hydrotreating products. The molecular type and homologous series matrix representation of petroleum fractions is a detailed characterisation approach that represents the composition of a stream in a matrix in terms of the carbon number range and compound classes existing in the petroleum fraction. A new strategy is developed for estimation of physical properties of middle distillate and heavy petroleum fractions with molecular type and homologous series matrix representation using group contribution methods.

A requirement for thermophysical property data of diesel fuels at conditions removed from ambient was identified. A series of measurements of the pressure-volume-temperature relations of diesel fuels was undertaken using a Micro-PVT apparatus at pressures to 300MPa in the temperature range 25 to 75°C. A new calibration procedure for this instrument was devised to enable measurements of high accuracy to be made. Viscosity measurements of diesel fuels over a range of temperature and pressure were made using the National Engineering Laboratory high pressure viscometer to pressures of 460MPa in the temperature range 25 to 100°C.Corresponding states theory was applied for compressed liquid density prediction. Improvement in density prediction in this region was found through use of iso-octane and heptadecane as reference fluids. Compressibility factors of these were represented by Tait-style equations. An iterative solution technique was developed to allow the corresponding states method to be applied to diesel fuelsusing limited density measurement and a guess value of boiling point as inputs. Densities predicted from this method agreed well with measurements made using the Micro-PVT apparatus. Hard sphere theory was applied as a method for viscosity prediction. Despite the complexity of the diesel fuel mixture, reasonable estimates of viscosity were made with limited measurement input at higher temperatures. At lower temperatures, an additional simple empirical correction term was required. A method of viscosity estimation of complex hydrocarbon mixtures based upon composition is presented. Further development of this would require additional measurements and greater characterisation of the fuel.

Visando a redução de poluentes emitidos pelos motores de combustão interna com ignição por compressão, que operam conforme o ciclo diesel, foram desenvolvidos nos últimos anos dispositivos para a operação destes motores com novos combustíveis, que além da redução de poluentes barateariam o custo de operação, devido à oportunidade de utilização de alguns combustíveis com boa disponibilidade. No presente estudo analisa-se a operação do motor diesel utilizando gás natural como combustível. Neste caso utiliza-se o óleo diesel apenas como combustível piloto, que será responsável pela ignição do segundo combustível, o gás natural. Em diversas publicações constata-se o ganho ambiental e econômico desta aplicação, porém nada é comentado em relação à alteração de índices de confiabilidade e surgimento de novos modos de falha. Neste trabalho verifica-se através de ferramentas de análise de confiabilidade, tais como a análise do tipo FMEA e Árvore de falhas, quais os principais modos de falha que serão inseridos no motor de combustão interna do tipo diesel quando este passa a operar como bi-combustível, com gás natural. Para tanto, necessita-se subdividir o motor diesel em subsistemas mostrando sua estruturação em árvores funcionais e integrando o kit diesel gás neste sistema. A partir da análise de confiabilidade verifica-se a probabilidade de ocorrência de novos modos de falha, que necessitarão da elaboração de novos planos de manutenção ou mesmo alterações no projeto do subsistema de injeção de gás natural. / In order to reduce pollutants emissions from internal combustion engines with compression bend ignition, designed to operate as the Diesel cycle, it has been developed in recent years devices for the addition of new fuels, which in addition to reducing pollutants could lower the cost of operation, due to the possibility of use of some fuels with good availability. In this case it is used only the diesel oil as the pilot flame, which is responsible for the ignition of the second fuel, the natural gas. Many publications discuss the environmental and the economic gain with the use of natural gas as fuel application, however nothing is said about the change of reliability indexes and the appearance of new failure modes in the engine. In this study through system reliability analysis tools such as Faillure Mode Effects and Analisys and Fault tree analysis it is analysed, which are the main failure modes that are inserted into the internal combustion engine when it comes to operate as dual fuel. For that analyses it is necessary to split the engine into subsystems showing its functional trees and integrating diesel gas kit in this system. New failure modes appear with greater severity than the existing in the traditional diesel engine system, leading to new design and maintenance practices. The end user, according to his need, will have one more parameter to choose whether to adopt a Diesel Gas system.

Visando a redução de poluentes emitidos pelos motores de combustão interna com ignição por compressão, que operam conforme o ciclo diesel, foram desenvolvidos nos últimos anos dispositivos para a operação destes motores com novos combustíveis, que além da redução de poluentes barateariam o custo de operação, devido à oportunidade de utilização de alguns combustíveis com boa disponibilidade. No presente estudo analisa-se a operação do motor diesel utilizando gás natural como combustível. Neste caso utiliza-se o óleo diesel apenas como combustível piloto, que será responsável pela ignição do segundo combustível, o gás natural. Em diversas publicações constata-se o ganho ambiental e econômico desta aplicação, porém nada é comentado em relação à alteração de índices de confiabilidade e surgimento de novos modos de falha. Neste trabalho verifica-se através de ferramentas de análise de confiabilidade, tais como a análise do tipo FMEA e Árvore de falhas, quais os principais modos de falha que serão inseridos no motor de combustão interna do tipo diesel quando este passa a operar como bi-combustível, com gás natural. Para tanto, necessita-se subdividir o motor diesel em subsistemas mostrando sua estruturação em árvores funcionais e integrando o kit diesel gás neste sistema. A partir da análise de confiabilidade verifica-se a probabilidade de ocorrência de novos modos de falha, que necessitarão da elaboração de novos planos de manutenção ou mesmo alterações no projeto do subsistema de injeção de gás natural. / In order to reduce pollutants emissions from internal combustion engines with compression bend ignition, designed to operate as the Diesel cycle, it has been developed in recent years devices for the addition of new fuels, which in addition to reducing pollutants could lower the cost of operation, due to the possibility of use of some fuels with good availability. In this case it is used only the diesel oil as the pilot flame, which is responsible for the ignition of the second fuel, the natural gas. Many publications discuss the environmental and the economic gain with the use of natural gas as fuel application, however nothing is said about the change of reliability indexes and the appearance of new failure modes in the engine. In this study through system reliability analysis tools such as Faillure Mode Effects and Analisys and Fault tree analysis it is analysed, which are the main failure modes that are inserted into the internal combustion engine when it comes to operate as dual fuel. For that analyses it is necessary to split the engine into subsystems showing its functional trees and integrating diesel gas kit in this system. New failure modes appear with greater severity than the existing in the traditional diesel engine system, leading to new design and maintenance practices. The end user, according to his need, will have one more parameter to choose whether to adopt a Diesel Gas system.

This thesis describes the development of a micromachine model and associated data acquisition system, which is used to study the improvement of the transient response of a ship's diesel generator set following a severe disturbance. The improvement in response is obtained by the use of transient rotor acceleration as a single extra feedback signal into the excitation and governor systems of the micromachine model. The response of the ship system is predicted by theoretical studies, which use a multiprocessor system to implement a Park's two axes, five winding model of the ship's generator together with the associated automatic voltage regulator and diesel governor models. The optimal feedback gains obtained from the theoretical studies are then used to obtain results from the micromachine system, a comparison between the theoretical and experimental results confirms the conclusion that a significant improvement in the system's transient response is obtained. This improvement is maintained when changes are made to the alternator load and the fault duration, without any alterations to the system feedback gains.

Diesel, one of the main petroleum products, is widely used in industry and transportation. Only high quality diesel product can survive in the more and more competitive market. The optimization methodology for diesel production and management is critical to refineries' profitability. LP/MIP models have been applied in diesel blending planning and scheduling in the last decades. With the benefits of reducing the model scale and computing efforts, LP/MIP models lead to operation results with inaccurate property estimation and profit loss due to the accuracy loss in the linearisation of blending models. To improve model accuracy, more accurate property prediction models for diesel blending should be incorporated into the refinery planning and schedule methods to improve decision making procedure in the case of scheduling for diesel blending, where academic effort is almost absent. A model for planning of refinery diesel streams is developed to optimise the diesel production of a refinery. Nonlinear blending models are applied to calculate blending properties more precisely than conventional linear models. Due to the large number of equations and variables, it may be generated to an infeasible solution if the given initial points are not good enough. To avoid this situation, a solution algorithm is proposed. Based on the NLP planning model, a model for scheduling diesel blending is developed. In order to improve the model accuracy, nonlinear blending correlations are used, which lead to a complicated MINLP problem that cannot be solved by existing MINLP solver directly. A robust solution algorithm is proposed in this thesis to help optimizing the MINLP problem. A case study of diesel production blending scheduling is introduced to illustrate how to model a diesel blending scheduling problem and the efficient and reliability of the solution algorithm. Besides, the proposed MINLP model and the solution algorithm can be extensively applied to other processes in a refinery, such as gasoline blending. Once gasoline blending models are taken into account, the model can be modified to optimize the gasoline blending scheduling problem.