Eucalyptus Biodiesel as an Alternative to Diesel Fuel: Preparation and Tests on DI Diesel Engine

Nowadays, the increasing oil consumption throughout the world induces crucial economical, security, and environmental problems. As a result, intensive researches are undertaken to find appropriate substitution to fossil fuels. In view of the large amount of eucalyptus trees present in arid areas, we focus in this study on the investigation of using eucalyptus biodiesel as fuel in diesel engine. Eucalyptus oil is converted by transesterification into biodiesel. Eucalyptus biodiesel characterization shows that the physicochemical properties are comparable to those of diesel fuel. In the second phase, a single cylinder air-cooled, DI diesel engine was used to test neat eucalyptus biodiesel and its blends with diesel fuel in various ratios (75, 50, and 25 by v%) at several engine loads. The engine combustion parameters such as peak pressure, rate of pressure rise, and heat release rate are determined. Performances and exhaust emissions are also evaluated at all operating conditions. Results show that neat eucalyptus biodiesel and its blends present significant improvements of carbon monoxide, unburned hydrocarbon, and particulates emissions especially at high loads with equivalent performances to those of diesel fuel. However, the NOx emissions are slightly increased when the biodiesel content is increased in the blend

Micro-scale trigenerative compressed air energy storage system: Modeling and parametric optimization study

International audienceIn this paper, a trigenerative compressed air energy storage system is considered giving priority to the electric energy production with the objective to apply it at a micro-scale, typically a few kW. A whole detailed thermo-dynamic model of the system is developed including the existing technological aspects and the relations between components. The study then focuses on investigating the mutual effects of the design parameters and their influences on the system performances, energy density and heat exchanger footprints via a parametric study. From this analysis, it is found that the temperature of the thermal energy storage, the number of compression stages and the effectiveness of heat exchangers should be selected as a trade-off between the system efficiencies, heat ex-changers footprints and the required number of expansion stages. Meanwhile, the selection of the maximum storage pressure is a choice whether to increase the energy density or the system efficiencies. An optimal design guideline of the above key parameters is then provided. This guideline, the method and the procedure presented in this paper can be applied to the optimization of the trigenerative compressed air energy storage and could be extended for the adiabatic one with minor changes. Based on existing technologies and using an optimal set of parameters, the round trip electrical efficiency of our system remains low at 17%, while the comprehensive efficiency reaches 27.2%. The poor performances are mainly linked to the exergy losses in the throttling valve and the low values of the component efficiencies at a micro-scale. The most optimization potentials are also addressed

BIO-FUELS EMPLOYABLE AT ALL SEASONS OBTAINED BY VEGETABLE OILS PROCESSING

Rezumat. Ca şi combustibilii pe bază de petrol, bio-combustibili

Adaptation des Angles d’Incidence de l’écoulement à l'entrée des roues d’un Turbocompresseur de Suralimentation à Géométrie Variable

L’amélioration des performances des turbocompresseurs de suralimentation fait l’objet de recherches continues. Ce travail a pour objectif d’étudier l’adaptation des angles d’incidence de l’écoulement à l’entrée des roues d’un turbocompresseur à géométrie variable en vue d’améliorer les performances du compresseur. Un modèle de prédiction des performances du compresseur incluant la prérotation à l'entrée du compresseur a été élaboré et validé. Les résultats obtenus sont présentés et discutés

EXPERIMENTAL AND NUMERICAL INVESTIGATION OF COMBUSTION BEHAVIOUR IN DIESEL ENGINE FUELLED WITH WASTE POLYETHYLENE OIL

The aim of this investigation is to evaluate the usability of waste polyethylene oil as an alternative fuel for diesel engines. The novel fuel is obtained by a pyrolysis process of waste polyethylene at 973 K. The obtained oil is tested in a single cylinder air cooled (TS1) direct injection diesel engine at 1500 rpm. Engine performances and exhaust pollutant emissions from Waste Polyethylene Oil (WPO) were analysed and compared to those obtained from the same engine fuelled with conventional diesel fuel. Results showed that the total fuel consumption of WPO is lower than that of neat diesel fuel due to the higher heating value of WPO. Brake Thermal Efficiency (BTE) is improved for WPO especially at low load. The exhaust gas temperature is lower for WPO than that of diesel at low and full load. CO and UHC are found lower, while NOx emissions are higher at high loads. Furthermore, the use of numerical investigation permits to optimize the injection parameters, which can help to take advantages of WPO fuel. The simulation results suggest advancing the injection timing

Modeling of a pyrolysis batch reactor using COMSOL Multiphysics

Plastic Pyrolysis is a thermal degradation process; it offers an important alternative energy. The aim of this study is to model a batch reactor to be used for plastic pyrolysis. Consequently, four experiments with different heating and cooling cycles are done using an empty pyrolysis batch reactor and four temperatures are measured at different locations on the reactor. On the other hand, the empty reactor is modeled and several simulations are done, using COMSOL Multiphysics software, under the same experimental conditions. By comparing the temperatures obtained from simulation to those measured experimentally, it is noticed that the results are very close with a maximum error of 4%, hence the model is validated

Numerical investigation of the partial oxidation in a two-stage downdraft gasifyer

International audienceno abstrac

Elaboration et caractérisation de couches minces de TiCN réalisées par pulvérisation magnétron RF

75 p. : ill. ; 30 cmL’étude des couches minces connait un essor considérable, aussi bien dans les approches théorique que dans les techniques expérimentales. L’industrie, par ses divers domaines, est la plus exigeante de la technologie des dépôts et des revêtements, ainsi, grâce au développement de nouveaux procédés d’élaboration de couches minces, on est arrivé à mettre au point des matériaux possédant des propriétés désirées. Des études ont été réalisées sur le composé TiCN et des résultats surprenant ont été obtenus sur les propriétés de ces couches. Plusieurs techniques sont utilisées pour déposer les couches minces de TiCxNy, parmi elles les techniques de dépôts chimiques en phases vapeur (CVD), qui travaillent en moyenne et hautes températures. L’avantage d’utiliser les techniques de dépôts physique en phase vapeur (PVD) réside dans le fait de travailler à des températures plus basses. De plus c’est une technique qui respecte l’environnement. Dans notre cas nous avons utilisé une des techniques PVD, à savoir la pulvérisation cathodique en faisant varier la pression totale, la puissance de la décharge, la composition du mélange gazeux et le temps de dépôts. L’objectif de notre travail, est l’étude de l’effet des conditions expérimentales sur les propriétés mécaniques, optiques et électriques des couches minces de carbonitrure de titane (TiCN) déposées par pulvérisation cathodique magnétron RF (13,56 MHz

Investigation on heat transfer evaluation for a more efficient two-zone combustion model in the case of natural gas SI engines

International audienceTwo-zone model is one of the most interesting engine simulation tools, especially for SI engines. However, the pertinence of the simulation depends on the accuracy of the heat transfer model. In fact, an important part of the fuel energy is transformed to heat loss from the chamber walls. Also, knock appearance is closely related to heat exchange. However, in the previous studies using two-zone models, many choices are made for heat transfer evaluation and no choice influence study has been carried out, in the literature. The current study aims to investigate the effect of the choice of both the heat transfer correlation and burned zone heat transfer area calculation method and provide an optimized choice for a more efficient two-zone thermodynamic model, in the case of natural gas SI engines. For this purpose, a computer simulation is developed. Experimental measurements are carried out for comparison and validation. The effect of correlation choice has been first studied. The most known correlations have been tested and compared. Our experimental pressure results, supported for more general and reliable conclusions, by a literature survey of many other studies, based on measured heat transfer rates for several SI engines, are used for correlation selection. It is found that Hohenberg's correlation is the best choice. However, the influence of the burned zone heat transfer area calculation method is negligible

Etude des possibilités d'amélioration du rendement à charge partielle des moteurs à allumage commandé

Doctorat en sciences appliquées -- UCL, 199