Distribution evolution of intake and residual gas species during CO2 stratification combustion in diesel engine

Exhaust gas recirculation (EGR) stratification contributes to simultaneous reduction of NOx and smoke emissions. For better understanding and management of EGR stratification, the distribution and evolution of intake and residual gas species inside diesel engine are investigated with numerical simulations. The simulations were initialized with the measured values of CO2 stratification experiments that were conducted on a heavy duty diesel engine by supplying CO2 to the tangential intake port only with different CO2 mass flow rate. The local and global distributions of O2, residual CO2 and intake CO2 in engine cylinder are expressed by mass concentration contours and global inhomogeneity respectively in this paper. As providing in global distribution cumulative curves and local visual information, the inhomogeneity of residual CO2 is higher than O2 and intake CO2, which indicates that significant in-cylinder CO2 stratification will be obtained by trapping more exhaust gas rather than supplying CO2 to the tangential intake port only. The distribution of O2 is almost homogeneous in both local and global information, which indicates that supplying CO2 to one intake port does not destroy O2 uniformity.