Effects of Spray Internal EGR Using CO ₂ Gas Dissolved Fuel on Combustion Characteristics and Emissions in Diesel Engine

We have proposed the application of Exhaust Gas Recirculation (EGR) gas dissolved fuel which might improve spray atomization through effervescent atomization instead of high injection pressure. Since EGR gas is included in the spray of EGR gas dissolved fuel, it directly contributes to combustion, and the further reduction of NO_x emissions is expected rather than the conventional external EGR. In our research, since highly contained in the exhaust gas and highly soluble in the fuel, CO₂ was selected as the dissolved gas to simulate EGR gas dissolved. In this paper, the purpose is to evaluate the influence of the application of CO₂ gas dissolved fuel on the combustion characteristics and emission characteristics inside the single cylinder, direct injection diesel engine. As a result, by use of the fuel, smoke was reduced by about 50 to 70%, but NO_x reduction does not have enough effect. However, NO_x emissions is reduced with external EGR, and the effect of NO_x reduction is effective by combined the external EGR and the CO₂ gas dissolved fuel.