Analysis on Combustion of a spark-ignited gasoline engine with hydrogen addition and cylinder cutoff

摘要

The combustion and emissions characteristics of a hydrogen-blended gasoline engine under idle and cylinder cutoff conditions were investigated in this paper. The cylinder cutoff strategy was tried with the engine running under four-cylinder, three-cylinder and two-cylinder working modes. For each cylinder closure strategy, hydrogen energy fraction in the total fuel was increased through increasing hydrogen injection duration. Meanwhile, the gasoline flow rate was reduced to ensure the hydrogen-gasoline blends in the working cylinders were kept at the stoichiometric condition. The experimental results demonstrated that both the coefficients of variation in engine idle speed and indicated mean effective pressure were reduced after the cylinder cutoff and hydrogen addition. Engine indicated thermal efficiency and the degree of constant volume combustion were improved while fuel energy flow rate was reduced with the increase of hydrogen blending fraction and the number of closed cylinders. When hydrogen energy fraction in the total fuel reached 20.6% at the two-cylinder cutoff mode, fuel energy flow rate was decreased by 41%, compared with that of the original engine at idle and stoichiometric conditions. Moreover, hydrogen addition and cylinder closure were effective on reducing engine HC and CO, except for NOx emissions at idle and stoichiometric conditions.