Abstract: The purpose of this research is to investigate a direct-injection single-cylinder engine fueled with different proportions of CH4 and N2-hydrogen blends under various engine load, the different influences of the proportion of hydrogen and nitrogen under various engine loads to the engine’s power, emission and efficiency are studied. The result shows that, in different load areas, when the percentages of N2 vary in the mixed gas fuel, adding H2 would have a different effect on the fraction on the maximum break pressure in the cylinder. The results also reveal that the emission of CO in the fuel within 25% N2 increases obviously than that within 15% N2. When there is no H2 in the fuel, the emission of CO increases nearly 30%. In addition, blending H2 is helpful to decrease the emission of HC. However, H2’s influence to the emission of CO in fuel with different percentages of N2 is different from its influence to the emission of NOx. When the fuel within 15% N2 is blended with 10% H2, the emission of CO increases but the emission of NOx decreases. Whereas, when the fuel within 25% N2 is blended with H2, the emission of CO decreases and the emission of NOx increases. Furthermore, with the engine load increasing, the effective gas consumption rate decreases. And blending hydrogen contributes to the increase of thermal efficiency.

Key words: direct injection, hydrogen, load characteristics, mixed fuel