The effect of rapeseed oil biodiesel fuel on combustion, performance, and the emission formation process within a heavy-duty DI diesel engine

Abstract

This study presents the influence of biodiesel fuel and blends with mineral diesel fuel on diesel engine performance, the combustion process, and the formation of emissions. The study was conducted numerically and experimentally. The aim of the study was to test the possibility of replacing mineral diesel fuel with biodiesel fuel made from rapeseed oil. Pure biodiesel fuel and three blends of biodiesel fuel with mineral diesel fuel were tested experimentally for that purpose on a heavy-duty bus diesel engine. The engine’s performance, in-cylinder pressure, fuel consumption, and the amount of produced NOx and CO emissions were monitored during experimental measurements, which were repeated numerically using the AVL BOOST simulation program. New empirical sub-models are proposed for determining a combustion model and emission models parameters. The proposed sub-models allow the determination of necessary combustion and emission model parameters regarding the properties of the tested fuel and the engine speed. When increasing the percentage of biodiesel fuel within the fuel blends, the reduction in engine torque and brake mean effective pressures are obtained for most of the test regimes. The reduction is caused due to the lower calorific value of the biodiesel fuel. Higher oxygen content in biodiesel fuel contributes to a better oxidation process within the combustion chamber when running on pure biodiesel or its blends. Better oxidation further results in a reduction of the formatted carbon and nitrogen oxides. The reduction of carbon emission is also attributed to the biodiesel fuel’s lower carbon content. It can be concluded from the obtained results that neat biodiesel fuel and its blends with mineral diesel fuel can be used in heavy-duty diesel engines with mechanically controlled injection systems as replacements for mineral diesel fuel. The agreement between numerical and experimental results confirms the usability of the proposed sub-model. The sub-models decrease time needed to preform numerical simulations with a reasonable amount of confidence without experimental results.