Thesis (M.S.M.E.)--University of Delaware, 2005. / Principal faculty advisor: Ajay K. Prasad, Dept. of Mechanical Engineering. Includes bibliographical references.

Thesis (Ph. D.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Max Deibert. Includes bibliographical references (leaves 74-77).

No description available.

Le développement de stratégies de combustion innovantes est nécessaire aujourd’hui pour répondre aux réglementations de plus en plus intransigeantes qui fixent les seuils d’émissions polluantes par les véhicules neufs. Parmi ces stratégies, l’approche Dual Fuel a montré un fort potentiel dans la réduction des émissions tout en maintenant des niveaux de rendement élevés. Le concept Dual Fuel est fondé sur la formation d’un mélange homogène d’air et d’un carburant volatile (essence, méthane, éthanol...) allumé par une injection directe d’un carburant à fort cétane (de type gazole) dans la chambre de combustion. Une compréhension détaillée des différents processus de combustion est primordiale pour aider au développement des stratégies Dual Fuel concrètes. Dans ce contexte, le développement d’un modèle adapté, couplé à des mesures expérimentales réalisées sur moteur optique, est indispensable pour optimiser la combustion Dual Fuel. Une étude numérique, fondée sur le couplage d’un modèle de combustion turbulente dédié à la propagation de flamme dans des milieux stratifiés (ECFM3Z) et un modèle de chimie tabulée pour la prédiction de l’auto-inflammation (TKI), a été menée afin d’évaluer la capacité des modèles existants à prédire les différents régimes de combustion qui pourraient exister dans les stratégies Dual Fuel. Des critères de transition ont été ajoutés et évalués afin d’améliorer le couplage des deux modèles et d’assurer la transition entre l’auto-inflammation et la propagation de flamme. D’autre part, l’étude expérimentale sur un moteur à accès optiques a permis d’étudier des variations de richesse, de carburant de prémélange et de taux de dilution et de caractériser de manière fine les mécanismes de la combustion Dual Fuel afin de servir de base de données aux développements de modèles CFD. / Advanced combustion strategies are required in response to increasingly stringent worldwide regulations governing exhaust gas emissions in the transport sector. Among these strategies, the Dual Fuel approach has shown potential to reduce engine-out pollutant emissions without penalizing combustion efficiency. The Dual Fuel concept relies on the formation of a homogeneous mixture of air with a highly volatile fuel (gasoline, methane, ethanol...) which is ignited by direct injection of a high-cetane fuel (Diesel fuel) in the combustion chamber. An improved understanding of the underlying physical phenomena and a detailed insight of the predominant combustion regime(s) are required in order to advance the development of the Dual Fuel combustion strategies. In this context, numerical modeling and optical engine measurements are combined to investigate Dual Fuel combustion. A numerical study, based on the coupling between a turbulent combustion model for flame propagation in stratified mixtures (ECFM3Z) and a tabulated kinetics model for auto-ignition (TKI), was conducted to evaluate the capacity of the existing models to cope with the various combustion regimes that might exist in Duel Fuel combustion strategies. Transition criteria were added and evaluated in order to improve the coupling between the two models and to better predict the transitions between auto-ignition and flame propagation. In addition, an experimental investigation, including equivalence ratio, premixed fuel and dilution variations, was performed in an optical engine. The objective was to apply advanced optical diagnostic techniques to thoroughly characterize the Dual Fuel combustion process and thus enhancing CFD model developments.

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Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2017. / Hydrogen is widely regarded as the clean energy carrier for future use in both transportation and electricity sectors. It has become an important new focus as an alternative fuel for cleaner energy technologies especially in the Polymer Exchange Membranes (PEM) fuel cells. However, specific technical and marketing demands must be met by a fuel processor for ultra-pure hydrogen production and at a very competitive cost. Liquid Petroleum gas (LPG) is seen as a potential source for low cost hydrogen production due to its relatively high energy density, easy storage and well-established infrastructure for fuel. There is a growing interest in the use of membrane in reaction engineering with the selective separation of the products from the reaction mixture provided opportunities to achieve higher conversion. Membrane separation technologies have potential to reduce operating costs, minimise unit operations and lower energy consumption. The overall goal of this project is to investigate the engineering feasibility associated performance of employing a palladium or palladium alloy membrane reactor for the production of ultra-pure hydrogen from the products of a liquefied petroleum gas (LPG) pre-reformer in determining the optimal process conditions for the production of high purity hydrogen from the LPG feedstock and evaluating of the performance of a Pd-based membrane in relation to maximizing the yield of hydrogen from the feedstock as well as minimizing the CO content of the reformate.

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This report is the result of a master’s thesis project which covers the cooling system in Volvo Cars’ fuel cell test vehicle. The purpose is to investigate if the existing cooling system in the fuel cell test vehicle works with the current fuel cell system of the vehicle, in terms of sufficient heat rejection and thus sustaining acceptable temperature levels for the fuel cell system. The project also aims to investigate if it is possible to implement a more powerful fuel cell system in the vehicle and keep the existing cooling system, with only a few necessary modifications. If improvements in the cooling system are needed, the goal is to suggest improvements on how a suitable cooling system can be accomplished. This was carried out by modeling the cooling system in the simulation software GT-Suite. Then both steady state and transient simulations were performed. It was found that the cooling system is capable of providing sufficient heat rejection for the current fuel cell system, even at demanding driving conditions up to ambient temperatures of at least 45°C. Further, for the more powerful fuel cell system the cooling system can only sustain sufficient heat rejection for less demanding driving conditions, hence it was concluded that improvements were needed. The following improvements are suggested: Increase air mass flow rate through the radiator, increase pump performance and remove the heat exchanger in the cooling system. If these improvements were combined it was found that the cooling system could sustain sufficient heat rejection, for the more powerful fuel cell system, up to the ambient temperature of 32°C.