Effect of EGR on Heavy-Duty Diesel Engine Emissions Characterized With Laser-Induced Incandescence

The regulations governing diesel engine particulate matter (PM) and oxides of nitrogen (NO_x) emissions are becoming increasingly stringent. New instrumentation is urgently needed to make accurate and precise measurements of PM emissions from low-emitting engines and emission control systems in a reasonable amount of time. Laser-induced incandescence (LII) is a technique for making temporally resolved measurements of soot volume fraction. LII offers real-time particulate concentration measurements over several orders of magnitude, and adds desirable information about particulate size and surface area. In this study, the exhaust gas recirculation (EGR) system of a heavy-duty diesel engine was tuned at eight speed/load conditions using quantitative LII. Soot concentrations measured by LII correlated strongly with measurements taken using the standard gravimetric technique and an AVL smoke meter.