HCCI: a combustion for the future?

The current success of the diesel engine is undoubtedly linked to the remarkable trade-off between performance and fuel economy that this offers to customers. Therefore, the necessary reduction of tail pipe pollutant emissions, such as nitrogen oxides and soot, must not threaten this contribution to reducing the global warming effect by unacceptable after treatment costs. By achieving a low temperature lean combustion, the HCCI allows generation of a very small amount of particles and NOx and therefore may avoid the need of a NOx trap for the main vehicle applications. Its success depends on the ability to control noise and hydrocarbon emissions at part load as well as to allow high power and torque densities. The aims of this paper are to show clearly how the injection strategy could have a positive effect on the engine results and to point out the main difficulties which are still to be solved.