Numerical simulation of low temperature oxygen-enriched combustion of diesel engine with the CFD & n-heptane sample model´s coupling

Multi-dimensional transient numerical simulation was done for low-temperature oxygen-enriched combustion process of 4100QBZL-2 diesel engine by using CFD software AVL-Fire and a simplified model of n-heptane oxidation coupling. To establish combustion chamber model and generate mesh with the ESE, in the computation process, FIRE will transfer and calculate the chemical kinetics model in each cell. Adjusting component volume fraction in intake air with: 21% O₂(atmosphere), 24% O₂ (oxygen-enriched combustion) and 24% O₂/10% CO₂ (low temperature oxygen-enriched combustion), then the calculation could use them. The results show: O₂ concentration 24% compared with 21% , the combustion rate is faster and the maximum pressure rise more than 0.2 MPa relatively. Combustion with 24% O₂/10% CO₂ intake air make the ignition time delay to TDC, the maximum pressure decreased to 10.7 MPa, the maximum temperature was 1548.4 K, which is reduced 60.2 K and achieved low temperature oxygen-rich combustion comparing with air combustion. With reduction of combustion temperature, NO emission is also lower than the case of combustion air.