Abstract
The increasing use of a common rail injection system in diesel engines has required much effort to understand the potential of such a system. This is because of its flexibility in injection timing, pressure and multi-injection compared with other types of injection systems. Therefore, much bench testing and simulation have taken place using this potential either for emission reduction or for performance improvement.
The purpose of this study was to understand the effect of the quantity on pilot injection and the effect of pilot interval on combustion noise together with NOx and soot. First the authors used a single cylinder engine with a common rail system to basically understand the effect of pilot quantity and interval on emissions including combustion noise. As well as testing, simulation was used as a tool to provide more information than that obtained by engine testing. To make sure the results of simulation representing the same trend as testing, the comparison between simulation and testing was shown to satisfy agreement in the case of pilot injection with varying pilot interval. Further simulation was aimed at understanding more about the effect of the quantity of pilot injection and the pilot interval to check the possibility of reducing both exhaust emissions and combustion noise if parameters could be obtained which are wider than the current system. Finally, the requirement as to quantity of pilot injection and the pilot interval concerning NOx, soot and combustion noise are discussed based on the results of the simulation.