Experimental Study on Combustion and Emissions Characteristics of a Spark Ignition Engine Blended with Hydrogen 2009-01-1923

In the view of low thermal efficiency and high emissions of spark ignition (SI) engines, this paper investigated the effect of hydrogen blending at intake ports to a SI engine on improving its economic and emissions performance. The experiment was carried out on a modified 4-cylinder SI engine on which hydrogen could be injected into the intake ports sequentially via an ECU based control system and mixed with gasoline on-line. The combustion and emissions characteristics of a hydrogen-blended IC engine were investigated under the conditions of 1500 rpm and the stoichiometric equivalence ratio with four different hydrogen volumetric fractions of 1%, 1.5%, 2%, and 3%. The test results demonstrated that the average brake thermal efficiency increased from 25.12 to 28.35% and the average coefficient of variation in peak in-cylinder pressure decreased from 6.8% to 3.62% when hydrogen fraction changed from 0% to 3%.

Ignition delay and the rapid burning duration were shortened; the peak in-cylinder pressure was increased; CO₂ and HC emissions were obviously lower with the increasing fraction of hydrogen in the intake. However, NOx and CO emissions were also increased. In a word, the addition of hydrogen to a gasoline-fuelled IC engine is a good way to improve engine performance.