Influence of coupling action of oxygenated fuel and gas circuit oxygen on hydrocarbons formation in diesel engine

Highlights: • Effect of fuel property and combustion characteristic on HC formation is investigated. • The influence weight of fuel oxygen, temperature and combustion duration on HC formation is studied. • The main factor influencing the decrease of HC emission is studied. • The HC formation under different oxygen environments is investigated. -- Abstract: In this paper, by comparing the effect of three fuels (B0, B20 and B20 + EHN) on engine hydrocarbon (HC) emissions in different oxygen concentrations, the relationship between the HC formation and the coupling effect of three factors: the fuel oxygen content, the combustion duration and the in-cylinder combustion temperature was analyzed. The result shows that the combustion temperature is the main influencing factor of HC emissions in the oxygen-enriched environment. However, in the medium-oxygen and oxygen-deficient environments, the fuel oxygen content factor has a greater effect than the combustion temperature. In view of the difference between the B20 fuel and the B20 + EHN fuel on HC emissions, the influence of the combustion duration on the HC emissions is much greater than that of the combustion temperature and with the decrease of the oxygen concentration, the influence weight of the combustion duration is weakened. In addition, the HC emissions from the B0 and the B20 fuels were compared. The result shows that the combustion duration is the main factor for HC emissions reduction, and the influence weight of the factor of combustion duration is greater than the sum of the oxygen content in the fuel and the combustion temperature.