Abstract
Keywords: hydrogen, direct injection, hydraulic system, spontaneous ignition, hydrogen addition
Hydrogen represents an adequate fuel for spark ignition engines due to its wide flammability limits and its higher burning rate which provide engine stable operating conditions at very lean air-fuel mixtures. Thus is possible to assure the engine load qualitative adjustment (opened full throttle) instead of load quantitative adjustment, providing also the decreasing of the pumping mechanical work.
Hydrogen engine performances are directly related to the used fuelling method and to the applied operating strategy.
The paper presents the results of the experimental researches carried on SI single cylinder engine fuelled with gasoline and hydrogen addition in different proportions and also only with hydrogen.
Hydrogen is admitted inside the cylinder after intake valve close thru a hydrogen valve mounted into the engine cylinder head. The hydrogen valve is actuated by a hydraulic system which provides the possibility to adjust the valve opening duration and valve opening moments, assuring a high flexibility of system tuning. The inlet of the hydrogen after the admission process provides the in-cylinder cooling effect avoiding spontaneous ignition phenomena. Another advantage of this fuelling method is that the inlet air quantity is not reduced.
The main goals are the increase of the engine efficiency and the decrease of the pollutants emissions level, in conditions of maintaining at least the same density of power as gasoline engine.
Are presented the engine performances at the fuelling with gasoline and hydrogen addition or only hydrogen and also are analyzed the influences of some adjusting parameters (dosage and hydrogen percent) on energetically and polluting performances of the engine.