Low Engine-Out NOx Emissions with DME Using High Pressure Injection 2007-01-4093
Dimethyl Ether (DME) is a promising future compression ignition fuel, particularly when derived from renewable, CO2-neutral feedstocks. While it is generally well-known that DME produces very little soot when burned, few studies have explored its low-temperature combustion behavior, where the potential for ultra-low engine-out emissions of both NOx and soot may exist. The present work shows the results of a single-cylinder engine operating with DME below the level of the US 2010 Heavy Duty Onroad Standard for NOx, without NOx aftertreatment. A high-pressure oil-over-fuel intensified injection system was used to maintain proper air utilization and high combustion efficiency, in combination with intake oxygen control using relatively high levels of EGR for low NOx. Fuel-related material issues notwithstanding, the engine results point toward a potentially cost-effective and efficient means of utilizing bio-derived fuels.