Abstract
Based on a six-cylinder direct injection diesel engine, the engine operating condition was simulated by application AVL-FIRE software coupling the n-heptane reduced mechanism containing polycyclic aromatic hydrocarbon (PAH) formation. The simulation and its verification test were both carried out under the maximum torque point. Then, the oxygen enriched combustion was simulated on the model, and the simulated condition was oxygen volume fraction from 21% to 30%. The simulation results show that, the oxygen enrichment (from 21% to 30%) increases the peak cylinder pressure of 3.32%, advances the start of combustion of 1.6 deg and rises the peak of average temperature in cylinder and wall heat flux. Among them, at the condition of 24% O2, the change of the results is the most significant. Benzene (A1) is one of the precursors of soot generated, the analysis of its impress-cuts of the mass distribution field in cylinder shows that, the increase of oxygen concentration can significantly inhibit the formation of benzene. But the oxygen enrichment makes the combustion more sufficient, cased a rise in the cylinder temperature, an extension in high temperature area, and an increment in the NOx emission.
Highlights
A lot of researches show that oxygen enriched combustion technology can obviously improve the combustion process of the cylinder, and have a significant effect on the power performance, fuel economy and emission characteristics of diesel engine [1]-[3]
Further exploring the effect of higher intake oxygen concentration on the combustion characteristics of the diesel engine is still significant for improving the combustion process and controlling the pollutant discharge of the diesel engine
Some parameters of the diesel engine are simulated under 4 different inlet oxygen concentration conditions, such as cylinder pressure curve, rate of heat release, temperature field and the concentration distribution of emissions, etc., so as to explore the influence of different inlet oxygen concentration on diesel engine combustion characteristic
Summary
A lot of researches show that oxygen enriched combustion technology can obviously improve the combustion process of the cylinder, and have a significant effect on the power performance, fuel economy and emission characteristics of diesel engine [1]-[3]. Liu an exacerbation in the combustion, an increment in the flame speed, a rise in the combustion temperature and a decrease in the fuel consumption It can significantly reduce the emissions of soot, but will lead to a substantial increment in NOx emissions [4]-[6]. The model built by application of AVL-FIRE software and coupling the n-heptane reduced mechanism containing the PAH formation were used for calculating some parameters, such as cylinder pressure curve, rate of heat release and the concentration distribution of emissions, etc These parameters were used to explore the influence of different inlet oxygen concentration on diesel engine combustion characteristic, so as to accumulate more theory basis in diesel engine
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