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Numerical study on the combustion process of a biogas spark-ignition engine

Carrera José L. (Universidad Politécnica de Zacatecas, Zacatecas, México)
Riesco José M. (Universidad de Guanajuato, Guanajuato, México)
Martínez Simón (Universidad Autónoma de Nuevo León, Nuevo León, México)
Sánchez Fausto A. (Universidad Autónoma de Nuevo León, Nuevo León, México)
Gallegos Armando (Universidad de Guanajuato, Guanajuato, México)

The fuel called biogas is obtained through anaerobic digestion of different types of organic waste, providing a way to tap the energy stored in organic matter. The use of this fuel is also attractive from the standpoint of global warming because its application does not register a net emission of carbon dioxide into the atmosphere. One possible use for this fuel is to feed the spark-ignition internal combustion engines. In the present, there is little information available about the process of combustion in internal combustion engines fueled by biogas. The combustion process of an internal combustion engine ignition powered by biogas is characterized in terms of the duration of combustion, i.e., depending on the time elapsed while the reactants (methane and oxygen) are transformed into products (mainly carbon dioxide and water). This study numerically evaluates the way in which the geometrical parameters such as the compression ratio and operating parameters like engine speed, the excess air, the time of spark timing and carbon dioxide content of biogas affect the evolution of the combustion process. To carry out this study, a five factors and two levels experiment was designed and conducted, based on which, the most influential parameters were identified. Equations expressing the combustion characteristic parameters, as a function of the geometric and operation parameters of a spark ignited engines, are delivered as a result.

Keywords: biogas combustion, computational fluid dynamics, Wiebe function, spark ignition