Emission Characteristics of CSOME in CRDI Diesel Engine with Multiple Injection Strategy

Diesel engines are successful in commercial applications both on-road and off-road due to their higher thermal efficiency and fuel economy. CO and HC emissions are less from diesel engines compared to its counterpart gasoline engine. But NO and PM (smoke) emissions are higher due to heterogeneous combustion. Simultaneous reduction of NO_x and smoke became a tough task faced by researchers to comply with the stringent emission regulations imposed upon. On the other hand, biodiesel as a replacement of petro-diesel in diesel engine applications is found to be a good means of solving the problems like depletion of fossil fuel and environmental degradation. The high temperature in the combustion chamber causes the formation of NO_x and heterogeneous mixing that causes smoke formation. In this work, an attempt is made to study the influence of splitting injection on NO_x and smoke in CRDI diesel engine operated with cottonseed oil biodiesel blend (B20). The injection was split into three pulses, namely pre, main, and post. The dwell between pre and main was varied, and dwell between main and post was fixed at 3° CAD. A fixed quantity of 0.5 mg/cycle fuel was injected in the post, whereas the fuel injection in pre is 10% of the main injection. At different main injection timings, the dwell between mail and pilot varied. The post-injection is maintained with a dwell of 3 CAD, which is very closely coupled with the main injection. From the recommended injection timing of 23° bTDC, the main injection timing along with post and pilot was retarded in steps of 3°. Baseline data was obtained with a petro-diesel single injection and B20 single injection at recommended 23° bTDC. For smoke reduction, the dwell of 10 CAD observed to be the best at all main injection timings. For NO_x reduction 20 CAD is better. For trade-off between NO_x and Smoke, in overall Dwell 10 CAD is observed to be better. It is found that splitting injection is very much helpful in simultaneous reduction of harmful emissions like NO_x and smoke from diesel engines.