Thermochemical Behaviour of Producer Gas from Gasification of Lignocellulosic Biomass in SI Engines

A study about the utilisation of producer gas from gasifiers for obtaining mechanical energy in a SI engine is presented in this work. Therefore, the influence of the gas composition and its thermodynamic properties on the combustion characteristics and on the engine performance are analysed. A home-made chemical equilibrium model which considers 28 chemical species was used to calculate the gas composition as a function of the gasification conditions, and to study the influence of the gas composition on some thermochemical parameters such as adiabatic flame temperature and heat release. The chemical kinetic package CHEMKIN III was also used to study its autoignition behaviour. Finally, a quasi-dimensional two-zone model for SI engines was used to calculate the knock tendency and to analyse the effect of fuel composition on some combustion parameters related to engine performance (IMEP, cylinder pressure, etc.). The comparison with the results obtained from some conventional fuels permits the evaluation of the potential of this technology with respect to conventional technologies and to propose modifications from the engine design, to take advantages of the different fuel characteristics.