An Investigation on the Regeneration of Lean NO _X Trap Using Dimethyl Ether 2020-01-1354

The ever-stringent emission regulations are major challenges for the diesel fueled engines in automotive industry. The applications of advanced after-treatment technologies as well as alternative fuels [1] are considered as promising methodology to reduce exhaust emission from compression ignition (CI) engines. Using dimethyl ether (DME) as an alternative fuel has been extensively studied by many researchers and automotive manufactures since DME has demonstrated enormous potential in terms of emission reduction, such as low CO emission, and soot and sulfur free. However, the effect of employing DME in a lean NO_X trap (LNT) based after-treatment system has not been fully addressed yet.

In this work, investigations of the long breathing LNT system using DME as a reductant were performed on a heated after-treatment flow bench with simulated engine exhaust condition. The scope of the study covers the regeneration effectiveness of NO_X on the LNT after-treatment system, the formation of the by-products, including ammonia (NH₃), nitrous oxide(N₂O), methane (CH₄). These by-products were measured and compared with the results when using other types of reductants, such as diesel, ethanol, n-butanol, under the same LNT test conditions. The test results reveal the constantly high regeneration effectiveness of DME as a reductant during the LNT regeneration process under different injection quantities. A lower amount of N₂O and NH₃, coming along with a higher amount of CH₄, are generated when using DME as a reductant, as compared to that of using diesel and n-butanol as reductants under the same conditions.