Effect of post-injection strategies on regulated and unregulated harmful emissions from a heavy-duty diesel engine

Abstract

An experimental study was carried out to analyze the influence of different post-injection strategies on the regulated and unregulated emissions from a heavy-duty compression ignition (CI) diesel engine. FTIR (Fourier transform infrared spectroscopy) was used to measure and analyze the exhaust emissions which include regulated such as NOx, soot, and unregulated emissions including acetaldehyde, formaldehyde, methane, ethane, propane, ethylene, propylene, and ethyne. Experimental results manifested that the post-injection technique can notably minimize the regulated and unregulated emissions as compared to a single main injection. Under different post-injection conditions, a trade-off relation was also found between soot and NOx emissions. In soot mitigation, the start of injection (SOI) at 40° crank angle (CA) incorporate with 5–15 mg post-injection fuel mass was proved very effective and about 26% lower soot emissions were recorded than single main injection. At SOI 20°CA, with 15 mg post-injection fuel mass, a reduction in the NOx emissions was observed up to 20% and in THC up to 60%. Unregulated emissions (other than formaldehyde and acetaldehyde) were found lower with 5, 10, and 15 mg post-injection fuel mass at 20, 40, 100, and 120°CA but increased at SOI of 60°CA than single main injection. In addition, light HCs, and THC emissions at SOI 60°CA were found to increase which could be beneficial for after-treatment devices.