In order to meet future requirements for emission reduction and fuel economy a variety of concepts are available for gasoline engines. In the recent past new pathways have been found using alternative fuels and fuel combinations to establish cost optimized solutions.
The presented concept for a SI-engine consists of combined injection of gasoline and hydrogen. A hydrogen enriched gas mixture is being injected additionally to gasoline into the engine manifold. The gas composition represents the output of an onboard gasoline reformer.
The simulations and measurements show substantial benefits to improve the combustion process resulting in reduced cold start and warm up emissions and optimized part load operation. The replacement of gasoline by hydrogen-rich gas during engine start leads to zero hydrocarbons in the exhaust gas. The mixed fuel operation enables high EGR rates up to 50% or extended lean burn limits resulting in reduced pumping losses and increased effective engine efficiency.
The set of measured data has been projected to the FTP-driving cycle to allow a reasonable comparability to existing concepts with conventional exhaust gas aftertreatment. The compared data show promising results with a new system approach.