Soot measurements using Laser Induced Incandescence for ethene combustion under engine-relevant conditions

With growing concerns over the detrimental effects of soot emission, it has become important to study possible emission reduction strategies and explore new measurement techniques to advance soot diagnostic capabilities. In this study, the potential of using nitrogen as a fuel diluent to reduce soot is measured in a series of combustion experiments under engine-relevant conditions using Laser Induced Incandescence (LU). In the first part of this research, a calibration was conducted to allow conversion of LIT signals into soot mass concentration values. This calibration was performed by measuring samples of different, but known, soot concentration with LII under different configurations. Secondly, a test plan was designed for this study using a statistical design-of-experiment technique, response surface methodology (RSM). The concept of R SM is to conduct a small number of experiments strategically and use the results to create an empirical model. Using this approach, a test matrix of 135 experiments was developed. Finally, combustion experiments were carried out in a shock tube. In these experiments, soot concentration within a combusting ethene jet was measured with LII. The LII results were then processed and used as inputs for building the empirical models, from which the following trends were observed: • . Addition of nitrogen was observed to lower the levels of soot within the fuel jet. • Increases in pre-combustion temperature reduced the level of soot detected. • Changes in fuel injection pressure and pre-combustion pressure were observed to cause competing effects on the level of soot detected. This might be caused by underlying changes in air fuel ratio associated with changes in the two pressures. The results of this work indicate fuel dilution with nitrogen can be a potential soot reduction strategy for non-premixed gaseous-fuelled combustion systems. This study also shows that the ability to instantaneously generate a map of soot distribution within a combusting fuel jet makes LII more powerful than traditional soot diagnostic techniques.Applied Science, Faculty ofMechanical Engineering, Department ofGraduat