Numerical study for influence of ozone on the combustion of biodiesel surrogates in a homogeneous charge compression ignition engine

Abstract

Biodiesel is a potential fuel for homogeneous charge compression ignition (HCCI) engines. The impacts of ozone on the combustion of biodiesel were investigated to achieve better performance in HCCI engines with ozone addition. By considering methyl decanoate (MD), methyl-9-decenoate (MD9D) and n-heptane as the surrogates, a skeletal biodiesel mechanism was constructed for predicting combustion process with ozone addition. On one hand, the influences of ozone addition on the two-stage ignition for HCCI engines fueled with biodiesel were studied on a variety of conditions, including initial temperatures, equivalence ratio and compositions ratio of surrogates. On the other hand, the enhancements of these conditions on promoting effects of ozone were analyzed. Compared to thermal and dilution effects, the chemical effect of ozone on the ignition plays a more important role. The H-abstraction reaction of n-heptane by O atom shows higher sensitivity to ozone and the ignition of n-heptane was promoted most. Results reveal the importance of H-abstraction reaction of fuel via O atom in the combustion of multi-components with ozone seeding. In addition, the initial temperature, equivalence ratio and blended fuel that is sensitive to ozone could be considered as auxiliary adjustments for ozone assisting to control combustion.