Effect of Wood-Gas Composition on Performance and Exhaust Emission Characteristics of a Large Spark-Ignition Engine

The gasification of wood allows the production of wood gas, which can be used as an energy source in large spark-ignition (SI) piston engines located in agricultural areas for generating electric power. The composition of wood gas depends on the fuel source and the processing technique. The primary objective of this paper is to investigate the main performance and emission characteristics of a multi-cylinder, four-stroke, turbocharged, spark-ignited engine fueled with three different types of wood gas at various air to fuel excess ratios. This engine is used for electricity production especially in small generator sets. In order to examine the effect of wood-gas composition on performance and exhaust emissions, a theoretical investigation is conducted by using a comprehensive two-zone phenomenological model. The results concern some of the main engine performance characteristics, i.e., brake specific fuel consumption and maximum cylinder pressure, and specific NO and CO emissions. The predictive ability of the model has been tested against experimental measurements. The results of simulation are found to be in good agreement with the variation trends of the experimental data with engine load. The conclusions from this investigation are valuable for the use of wood gas as a full supplement energy source in a heavy-duty, spark-ignited engine used for electric power generation in agriculture areas, where the composition of the produced wood gas is not fixed but depends on the fuel feedstock source and the type of gasification. (C) 2013 American Society of Civil Engineers.