Experiment Investigation Of Combustion And Emission In Engine By Variable Intake-air Composition Of Oxygen And Nitrogen

The oxygen-enriched intake technology can decrease the ignition point of the fuel and increase the combustion speed to promote the completely combustion. In addition, the temperature of the flame is raised, the heat utilization ratio is increased, and the excess air coefficient is reduced. The nitrogen-enriched intake technology can control the combustion process by restraining the combustion, reducing the NOx emission effectively. It has the potential to replace EGR. It is possible to make the engine obtain the optimal power performance, economical efficiency and emission controlling performance by altering the air composition of oxygen and nitrogen according to the working condition.On the basic of prime study on idling condition and mainly aiming at load condition, this paper carried out experimental study on engine performance and emissions by altering the air composition of oxygen and nitrogen. According to previous experiment and theoretical analysis, we choose the oxygen degree of intake air as 21%, 23%and 25% and study the engine performance and emissions characteristic at different load or velocity with oxygen-enriched intake air. The results indicate that when the oxygen degree is raised from 21% to 25%, the engine power can be improved above 10% and the oil consumption rate can be reduced about 15%; HC emission is reduced from 33%~53%, CO emission is reduced from 29%~79%, but NOx emissions is increased obviously. In the study on nitrogen-enriched intake air, we choose the oxygen degree of intake air as 79%,81% and 83% respectively. The experiment results indicate that after the raise of the nitrogen degree of intake air, the speed of the flame become slower, and the temperature of the combustion is decreased, the NOx emission is restrained obviously. But the prolonged delayed combustion period and the deterioration of combustion stability is more obvious. It results in the decrease of thermal efficiency. The power and torque of the engine become worse. Therefore, to control the NOx emission by nitrogen.enriched intake air, the corresponding engine ignition system and adjust of intake system is needed. In limited extension, the NOx can be restrained well by cooperative control.The combustion of the engine is mainly restricted to the composition of oxygen and nitrogen of intake air. The former improve the combustion, and the latter hinder the combustion. The share of them is the basic element of the control in combustion process. The optimization control on combustion and emission can be carried out by the reforming of composition of intake-air. Researching for the front control of combustion and emission and developing the pre.processing technology is benefit to combustion control. What is more, it is benefit to reducing fuel consumption, so as to save energy resources and reduce the harmful emissions from the fountainhead.