Numerical Investigations on Split Injection Strategies to Reduce Unburned Hydrocarbon Emissions of a Premixed Charge Compression Ignited Light-Duty Small-Bore Diesel Engine
2022-01-0553
03/29/2022
- Event
- Content
- Premixed Charge Compression Ignition (PCCI) is a promising low-temperature combustion (LTC) strategy to achieve a simultaneous reduction in oxides of nitrogen (NOx) and soot emissions without relying on after-treatment devices. One of the significant shortcomings of PCCI operation is a high unburned hydrocarbon (HC) and carbon monoxide (CO) emissions resulting from fuel spray-wall impingement due to early injection of diesel. Narrow-angle direct injection (NADI) helps in reducing the wall wetting of fuel. But it is effective only at lower loads. At mid and higher loads, it increases soot and CO emissions in small-bore diesel engines due to the formation of fuel-rich pockets in the piston bowl region. The present study intends to address this problem using a split injection strategy. A 3-D CFD model is developed and validated with experimental data at two load conditions. Simulations are performed using a commercial CONVERGE CFD software. Split injection strategies are explored using wide (148 degree) and narrow (88 degree) spray angles. Based on the investigations, it was concluded that a start of the main injection of 20 deg. bTDC and 30 deg. bTDC were optimal for wide and narrow spray angles, respectively. For both cases, a dwell time of 15 deg. CA was found to be optimal. Compared to single injection, split injection resulted in 2% and 4% improvement in thermal efficiency for wide and narrow spray angles, respectively. Split injection results in a reduction of 83% and 80% in CO, 56% and 64% in soot and 48% and 60% in HC emissions for wide and narrow included angle, respectively, when compared with single-injection NADI-PCCI combustion.
- Citation
- Pradeep, V., and Krishnasamy, A., "Numerical Investigations on Split Injection Strategies to Reduce Unburned Hydrocarbon Emissions of a Premixed Charge Compression Ignited Light-Duty Small-Bore Diesel Engine ," SAE Technical Paper 2022-01-0553, 2022, .