Search Results

Poor air quality represents a serious threat to the health and quality of life of people across the globe, as well as increasing the burden on the U.S. and international economy. These threats exist despite progress being made at many local, state and federal levels to curb the growing pollution problem due to increased industrialization and the expansion of motor vehicle usage. Many approaches have been developed over the last decade to combat pollutants [primarily oxides of nitrogen (NOx), hydrocarbons (HC), particulate matter (PM) and carbon monoxide (CO)] contributed by mobile sources. This paper will focus on PM and NOx, the two pollutants most commonly associated with heavy-duty diesel engines. The paper will also focus on the development of an air management technology designed to increase combustion efficiency within the engine chamber that reduces engine-out emissions while increasing fuel efficiency and engine performance.

Combustion processes inside the engine cylinder dictate engine power, efficiency and emissions. Following compression, burning proceeds as air and fuel mix to the composition necessary for combustion to take place. In the diesel engine, fuel is injected in the cylinder into high pressure and temperature air. The engine has less time to form the air-fuel mixture, which is less homogenous as a result. This creates periods during the combustion phase where the air to fuel relationship is non-optimized. This is particularly apparent during low-end operating cycles. Traditionally, efforts to reduce engine-out emissions have concentrated on fuel management. Development of two advanced technologies on turbocharged diesel engines have focused instead on air management with the optimization of this relationship of air to fuel.