A detailed chemical model was implemented in the KIVA-3V two dimensional CFD code to investigate the effects of the spray cone angle and injection timing on Premixed Charge Compression Ignition (PCCI) combustion and emissions in an optical research diesel engine. A detailed chemical model for Primary Reference Fuel (PRF) consisting of 157 species and 1552 reactions was used to simulate diesel fuel chemistry. The model validation shows good agreement between the predicted and measured pressure and emissions data in the selected cases with various spray angles and injection timings. If the injection is retarded to -50 degrees after Top Dead Center (TDC), the spray impingement at the edge of the piston corner with 100 degree injection angle was shown to enhance the mixing of air and fuel. The minimum fuel loss and more widely distributed fuel vapour contribute to improving combustion efficiency and lowering uHC and CO emissions in the engine idle condition. Finally, the coupling of CFD and multi-zone Stochastic Reactor Model (SRM) was demonstrated to show improvement in CO and uHC emissions prediction.

The figure shows the simulated spray evolution (left) and comparison with laser measurements (right). The comparisons shown are at (top to bottom): 0.21 ms, 0.35 ms, 0.41 ms, 0.53 ms and 0.59 ms after injection.