Experimental Study on Combustion and Emissions Characteristics of a Spark Ignition Engine Blended with Hydrogen

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.