A numerical modeling on the emission characteristics of a diesel engine fueled by diesel and biodiesel blend fuels

A numerical modeling study was performed to investigate the impacts of biodiesel blend ratio on the emission formation processes of a diesel engine. Simulations were conducted using 3-D CFD simulation software KIVA4 coupled with CHEMKIN II. The integrated chemical kinetics with 69 species and 204 reactions comprises the significant reaction pathways of methyl decanoate (C11H22O2), methyl-9-decenoate (C11H20O2) and n-heptane (C7H16), which are capable of emulating different biodiesel blend ratios. The nitrogen monoxide (NO) and carbon monoxide (CO) formation mechanisms were also embedded. To better represent the biodiesel fuel properties, detailed chemical and thermo-physical properties of biodiesel were calculated and integrated into the KIVA4 fuel library. The simulated cases were validated against the experimental results by comparing the in-cylinder pressure and heat release curves for B100, B50, and pure diesel fuels at 2400 rpm under 10% load, 50% load and 100% load, respectively. Good agreements with a maximum of 5% deviation on the peak cylinder pressure were obtained. Simulation results revealed that at 10% load conditions, with the increase of biodiesel blend ratio, the overall CO development and oxidation window is narrowed, and a remarkable increase in CO emission is observed.