Abstract
Because of the excessive pollution made today by the engines using classic fuels, the use of alternative fuels in internal combustion engines represents a solution for today. Also statistics show that the hydrocarbon resources from which the oil is made will disappear in the next 50 years, so the industry has to be ready for these alternative fuels. Many researches using different alternative fuels have been conducted and most of them had good results. Hydrogen is one of the best alternative fuels due to his properties. Regarding the most important aspect, pollution, hydrogen does not contain any carbon and therefore combustion of hydrogen does not create carbon-containing emissions such as CO2, CO, HC or PM. Other physical-chemical properties of hydrogen show good combustion characteristics such as a burning rate higher comparative to other hydrocarbon fuels, wide flammability limits and very low ignition energy. The paper presents theoretical and experimental researches regarding the use of hydrogen in S.I. engines. The tests were carried out on an experimental mono-cylinder engine with normal admission system, three valves: one air inlet valve, one hydrogen inlet valve and one exhaust valve. From the researches made, hydrogen proves to be an excellent fuel for S.I. engines. It represents a viable alternative for replacing the fossil fuels, providing the advantage of maintaining the existing basic principles of the engine, but improving the break thermal efficiency and reducing the NOx emissions to very low levels.
Keywords: Hydrogen, Internal Combustion Engine, Emissions, Modeling, Experimental Research