A Comprehensive Experimental Study on NOx Emissions and Fuel Consumption for SI Engine Fuelled with a Mixture of Gasoline, Hydrogen-rich Synthesis Gas and Hydrous Ethanol

Increasing efficiency and decreasing pollutant emissions of spark-ignition engines are of primary concern in the automotive industry and environmental research. This chapter presents an intensive study of investigating the effect of operating a spark-ignited engine with several mixtures of binary blends made of conventional (local Saudi Gasoline 91 and 95) and nonconventional (anhydrous- and hydrous-ethanol) liquid fuels on reducing NOx exhaust emission levels and improving fuel consumption. In addition, the influence of injecting on-board produced plasma-assisted hydrogen-rich syngas into the mixtures of the test fuels is also discussed. Furthermore, an insight into enhancing the production of on-board plasma-assisted hydrogen-rich syngas and erosion resistance of different materials for the plasma’s cathode is provided. In all tests, the engine was operated at a constant speed, compression ratio and ignition timing while varying consistently the engine load from idle to 10 kW and the equivalence air-fuel ratio between stoichiometric and lean operation. At stoichiometric operation and without injecting the hydrogen-rich syngas, the results showed that the maximum reduction in NOx emission levels was caused by blending hydrous ethanol with a water content of 40% into both conventional gasoline 91 and 95 fuels, reaching 55% and 60%, respectively. Furthermore, with the injection of the hydrogen-rich syngas, the reduction was increased to 63% and 72%, respectively. While operating the engine under a lean air-fuel ratio, a significant decrease in NOx emission levels of hydrous ethanol-gasoline blends relative to other test fuels was seen with further decrease as the equivalence air-fuel ratio became leaner. Better anti-erosion resistance of lanthanide tungsten cathode relative to which made of hafnium metal was observed.