Effects of intake oxygen mole fraction on the near-stoichiometric combustion and emission characteristics of a CI (compression ignition) engine

In the present study, the combustion and emission characteristics under various equivalence ratio up to stoichiometric condition were experimentally investigated in a CI (compression ignition) engine. In order to control the equivalence ratio, the O2 mole fraction of intake gas was reduced from 21 to 11.16 % by adding only N2 to intake gas while the injected fuel quantity was held constant. The test was used a single-cylinder compression ignition (CI) engine with a displacement volume of 373.3cc, a compression ratio of 17.8, a re-entrant type piston-bowl. The emission measurement instruments consisted of emission bench (MEXA-9100D, HORIBA) and smoke meter (AVL-415S, AVL).