Numerical investigation on low octane gasoline-like fuel compression ignition combustion at high load

摘要

A three-dimensional numerical investigation is conducted to explore the effects of fuel octane number on combustion and emission characteristics in compression ignition combustion at high load condition. The results show that the low octane gasoline-like fuel PRF70 exhibits better performance than conventional high octane gasoline PRF92 at the current operating condition. Details of the combustion process of PRF70 and PRF92 are analyzed and compared. It's revealed that the poor combustion performance of PRF92 mainly results from overmixing, while it can be significantly improved with PRF70 due to its higher reactivity than PRF92. The performances of PRF70 and PRF92 are also compared over a wide range of EGR and SOI timing conditions. It's found that, within the scope of this study, PRF70 can not only obtain higher thermal efficiency while maintaining lower MPRR, but also significantly reduce both HC and CO emissions with similar soot and NOx emissions compared to PRF92, indicating the potential of PRF70 for high load extension. In addition, energy distribution analysis shows from a macroscopic perspective that compared to PRF92, the improved thermal efficiency of PRF70 mainly results from lower exhaust and combustion losses.