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Show METHANE-CARBON DIOXIDE MIXTURES AS A FUEL G. A. Karim and L Wierzba Department of Mechanical Engineering The University of Calgary Calgary, Alberta, Canada T 2 N 1N4 Abstract The presence of carbon dioxide with methane is often encountered to varying proportions in numerous natural, industrial and bio-gases. The paper discusses h o w such a presence modifies significantly the thermodynamic, kinetic and combustion characteristics of methane in air. Some experimental results are presented showing h o w the performance of gas fuelled engines of the spark ignition and compression ignition types is adversely affected by the increasing presence of carbon dioxide with the methane. The bases for these trends are discussed and some guidelines towards alleviating the adverse effects of the presence of carbon dioxide in such fuel mixtures are presented. Introduction The presence of some carbon dioxide with the supplies of the gaseous fuel methane can be encountered in numerous situations in practice. For example, carbon dioxide can be found with methane in some natural gases, in bio-gases produced through the fermentation of organic waste materials, in the byproducts of the gasification and reforming of heavy oil or coal, in waste gases of the petrochemical industry and in landfill, coal beds and sewage gases. The composition of such gas mixtures which may also contain the diluents nitrogen and water vapour can vary very widely depending on their origin and the m o d e of their production. Moreover, the increased practice of resorting to some exhaust gas recirculation in methane fuelled combustion devices primarily for emissions control, will also result in the fuel being utilized in association with some carbon dioxide and the other diluents. Such a presence can bring about significant adverse changes to the combustion characteristics of the methane and undermine its effective utilization in conventional combustion devices. The present contribution aims at reviewing the origin and nature of the main limitations of the combustion of such gaseous fuel mixtures in air so as to effect ultimately their efficient, reliable and economically acceptable utilization in various combustion devices. 1 |