Review of the advances in integrated chemical kinetics-computational fluid dynamics combustion modelling studies of gasoline-biodiesel mixtures

Abstract

Biodiesel combustion in diesel engines is associated with reduced carbon monoxide, particulate matter and unburned hydrocarbons emissions, but several concerns remain including carbon deposition, low thermal efficiency and elevated nitrogen oxides production. To this end, the incorporation of gasoline additive has been proposed as a solution to the drawbacks posed by biodiesel. Integrated chemical kinetics-computational fluid dynamics combustion modelling is a widely used tool to understand the combustion characteristics of new fuel mixtures. This study provides a thorough review of the advances gained in the field of combustion modelling for gasoline-biodiesel mixtures. A thorough appraisal of gasoline surrogate mechanisms such as the primary reference fuel, toluene primary reference fuel and multi-component mechanisms is presented. Developments in the biodiesel surrogate mechanisms such as methyl-butanoate, methyl-hexanoate, methyl-heptanoate, methyl-octanoate, and methyl-decanoate are also discussed. Furthermore, this study also presents a wide-reaching analysis of the modelling results looking into the effects of gasoline addition on the combustion characteristics of gasoline-biodiesel mixtures. From the modelling studies reviewed, the addition of gasoline brings about an increase in the ignition delay timing, in-cylinder pressure and heat release rate (at high temperatures). Also, the rise in gasoline fraction (at low temperatures) leads to the reduction in the combustion duration, nitrogen oxides and soot emissions, but increased carbon monoxide and hydrocarbons emissions. Finally, increased gasoline fraction improves the fuelling economy (at high temperatures) and the combustion stability (at low temperatures).