Transient Analysis of Engine Nano-Particles Using a Fast-Scanning Differential Mobility Particle Analyzer 2004-01-0971

The characterization of engine particulate matter size distributions has become an important topic in the investigation of particulate matter formation, transport, and emission reduction technology. The majority of current size distribution analyses are conducted during steady state engine conditions. Although steady state analysis is valuable, most engines in mobile applications are operated under transient conditions, creating a demand for the transient state analysis of particulate emission patterns. In order to measure the instantaneous emissions of an engine under transient conditions, instrumentation must respond to the changing engine conditions as quickly as possible. In this study, a fast-scanning nanometer Aerosol Size Analyzer (n-ASA) was used to measure the emitted particles of a heavy duty diesel engine during transient simulations. The results showed patterns of PM emissions at key areas throughout the test. It was found that when the engine was decelerating, which can include reduced engine speed, load, or exhaust gas temperatures, a favorable condition was created for the formation of nuclei-mode particles through gas-to-particle conversion. While the engine was accelerating, which generally consisted of increased engine speed, load, fuel consumption, and exhaust gas temperatures, accumulation-mode diesel particles tended to be produced.