Study of the combustion of alternative fuels for spark-ignition engines (S.I.E.)

Abstract

This paper presents an experimental study on the combustion and pollutant emissions resulting from the use of an alternative fuel blend in spark-ignition engines (S.I.E.). The analysed blend contains naphtha (extraction gasoline, octane number 71), methanol (99.7%) and a methanol – cellulose trinitrate solution, the aim being to investigate the influence of nitrated cellulose on the octane number of the resulting fuel. The determinations were carried out on a small-displacement single-cylinder engine (Honda WX 10, 25 cm³), and the octane number was validated on a dedicated test bench equipped with a variable compression ratio engine of CFR Waukesha F1/F2 type. The pollutant emissions (CO, CO₂, HC, O₂, λ) and the opacity were measured using AVL DiGas 480 and AVL DiSmoke 480 diagnostic equipment. The aim of the research is to evaluate the combustion behaviour of the proposed blend and the level of generated emissions, with a view to identifying a viable alternative fuel solution for spark-ignition engines. The results are reported as a preliminary investigation, obtained on a single small-displacement engine and at a limited number of operating regimes, and are complemented by an octane-number validation on a CFR engine and by in-cylinder pressure measurements on a GUNT CF152 bench.