A Numerical Study of Multiple Fuel Injection Strategies for NOx Reduction from DI Diesel Engines

Abstract

Diesel engines are becoming more and more popular as a power source due to their better fuel efficiency over gasoline engines. On the other hand, diesel engines have higher NOx and particular matter emissions compared with gasoline engines. Stringent emission regulations on internal combustion engines have been implemented by governments all over the world, especially in USA, Europe and Japan. NOx emission control has become one of the biggest challenges in the design of diesel engines. Previous experiments and simulations have shown the potential of the multiple fuel injection strategy in reducing NOx emission from diesel engines. In this study, detailed numerical simulations have been conducted for up to 5-split fuel injections as compared to the conventional single fuel injection strategy. The software package employed in this study is KIVA-3V release 2, a multi-dimensional computational code for solving chemically reacting flow problems. The combination of the multiple fuel injection strategy with the Exhaust Gas Recirculation technique is studied as well. The results from this study have demonstrated that the use of the multiple fuel injection strategy can effectively reduce the NOx emission from diesel engines. Combined with other NOx reduction techniques, the multiple fuel injection strategy is a very promising way for modern diesel engines to meet the ever-stringent emission standards.