Direct-Injection Hydrogen SI-Engine - Operation Strategy and Power Density Potentials 2004-01-2927
Using the regenerative fuel hydrogen in a vehicle's internal combustion engine application requires not only a custom engineered combustion concept, but also optimized operation strategies. That enables the availability of high power output as well as the abolition of critical exhaust gas emissions in combination with high efficiencies.
The direct injection hydrogen internal combustion engine offers the potential to achieve higher performance and dynamic characteristics than a conventional gasoline fuelled engine.
A specially designed single cylinder test engine equipped with external and internal mixture formation systems was used to investigate the potentials of a combined operation of DI (direct-injection) and PFI (port fuel injection) and the effects of various injection pressures.
With direct injection high load operation at stoichiometric mixtures was possible. Maximum engine power output could be increased by more than 20 % above a conventional gasoline engine in combination with an indicated efficiency of more than 33 %.
At low engine loads lean operation using external mixture formation was investigated. With this strategy indicated fuel efficiencies of more than 40 % were achieved.
For the entire operating range of the engine, an operation strategy is proposed which enables high power-density, high engine efficiencies as well as lowest environmental impact due to a virtually CO2- and NOx- free operation.
Visualization methods were successfully used for enhancing the engines combustion concept layout and to compare with the simulation models used.
Simulation tools such as pressure curve analysis, 1-dimensional flow simulation and an engine loss analysis were developed and successfully deployed in designing the current test engines.