Strict new governmental regulations regarding emissions force engine manufacturers to develop and implement new technologies for all types of diesel engines.
In the present study, the exhaust emissions of a turbocharged, intercooled direct-injection off-road diesel engine were reduced by retarding the injection timing and by using exhaust gas recirculation (EGR). The effects of the retarded timing and EGR on the general engine performance, regulated exhaust emissions and exhaust particle number and size distribution were examined.
The results showed that at some loads, the retarded injection increased the number of ultrafine particles, but the number of large particles decreased. At some loads, the injection retardation resulted, however, in increased particle numbers within the whole particle size range.
The increase in the EGR rate increased the particle number steadily throughout the entire particle size range. At a given EGR rate, the particle numbers were very similar independent of, whether the recirculated exhaust gas was cooled or not. The use of slightly different fuels in cooled and uncooled EGR tests made the comparison, however, slightly uncertain.