EXPERIMENTAL AND NUMERICAL SIMULATION ON BIOGAS FLAME PROPAGATION CHARACTERISTIC IN SPARK IGNITION PREMIXED COMBUSTION

摘要

Biogas is a sustainable and renewable fuel that is produced in digestion facilities. Biogas can be utilized to replace energy derived from fossil fuels, and hence reduce emissions of greenhouse gasses. Based on the chemical composition analysis, the composition of biogas produced in East Java, Indonesia consists of 66.4 methane, 30.6 carbon dioxide and 3 nitrogen. Demands for improved engine design and replacing fossil fuels, in terms of power output, efficiency and emissions control, require improved fundamental understanding of the combustion processes that occur within the cylinder. The most importance characteristic is the burning velocity, which directly affects pressure development and often is expressed in terms of laminar burning velocity. The laminar burning velocity is the most important flame propagation characteristic in spark ignition premixed combustion. The experimental laminar burning velocity of biogas premixed combustion was measured in a high pressure fan-stirred bomb. Analysis based on careful photographic observation has been used to determine precisely defined (unstrectched) laminar burning velocities. The numerical simulation has been done using the Premix module of CHEMKIN. The reaction mechanism used is GRI Mech 3.0 consisting of 325 elementary chemical reactions and associated rate coefficient expressions and thermochemical parameters for the 53 species involved in them. Based on the experimental investigation and the numerical simulation, the unstrecthed laminar burning velocity as the important characteristic of flame propagation in biogas premixed combustion has been found for initial conditions of a stoichiometric at room temperature and atmospheric pressure. Finally, The laminar burning velocity of biogas is better than pure methane in lean and rich mixtures at room temperature and atmospheric pressure initial conditions. Biogas has a good premixed combustion flame propagation characteristic and could be an alternative to replace the fossil fuels