Controllability Of Variable Composition Of Nitrogen-rich Or Oxygen-rich Intake-air In The Diesel Engine

Controllability of variable composition of nitrogen-rich and oxygen-rich intake-air inthe diesel engine is an active control technology that achieved by changing the componentsof oxygen and nitrogen into the air in the cylinder, oxygen concentration distribution isrestructured in order to improve combustion and reduce emissions. Nitrogen-rich andoxygen-rich combustion engine intake respectively plays the role of flame and combustion.By changing the concentration distribution of nitrogen and oxygen components, enginequenching phenomenon, the harsh environment of incomplete combustion, the localtemperature is too high is improved and ultimately to reduce emissions, the power andeconomy purposes is improved.The simulation uses CFD commercial software FLUENT. The study simulated theintake stroke and compress stroke of Nitrogen-rich and Oxygen-rich intake-air. In order toachieve the oxygen concentration distributes thinner in the middle and thicker in the edge incylinder, the study designed direct injection and analyzed the distribution of the flow fliedand the oxygen concentration field on the end of compress stroke.This paper divided into two parts: nitrogen-rich intake-air control and oxygen-richcontrol. The study analyzed the controllability of variable composition of nitrogen-rich andoxygen-rich intake-air. It is analyzed by controlling the position of direct injection, injectionangle, injection strategy and injection pressure. It can be known that different workingcondition adapt to control scheme by analyzing the different rotating speed. The researchmethod is to analyze the flow flied of the rich fluid. It can realize control of combustion andreduce harmful gas emission through the comparative analysis to select the best rich fluidinjection solution. This article not only researched the naturally aspirated diesel engine, alsoapply the same method of turbocharged diesel engine.Before the study of nitrogen-rich and oxygen-rich intake-air, this article designed themodel of the combustion chamber. With tangential airway and spiral airway is established through comparison and analysis. The spiral airway formed strong intake vortex. The oxygenconcentration presents thinner in the middle and thicker in the edge in cylinder at the end ofthe compress stroke. And then set up three different combustion chamber, they are allboosting the vortex and they all presents thinner in the middle and thicker in the edge incylinder at the end of the compress stroke through analysis. But vortex intensity abates onthe compression stroke. Type III combustion chamber is adapted in order to achieve thenitrogen-rich and oxygen-rich intake-air.Through the study of the nitrogen-rich intake-air control, it is analyzed the spatiallocation and angle of nitrogen-rich nozzle. The results shows that the oxygen concentrationpresents thinner in the middle and thicker in the edge in cylinder when the nozzle in theposition II and10°to the cylinder axis layout. In analyzing the effects of injection timing,it was found the oxygen concentration showed thinner in the middle and thicker in the edgebefore the injection process60°CA. In analyzing the impact of different nitrogen-richinjection pressure, it was found that distributions of oxygen concentration are ideal when1atm,1.5atm and2atm nitrogen-rich jet. As the pressure increases, the increase of nitrogeninjected into the cylinder, the average oxygen cylinder mass fraction decreased. With theincrease in injection pressure, rate of change of the oxygen concentration increases. Inanalyzing the effects of different engine speed, it is found oxygen concentration distributionof the same field when the engine speed is800r/min,1500r/min and2000r/min. The rate ofchange of the oxygen concentration is substantially the same as this rich nitrogen intakepatterns for different engine speeds. Finally, the nitrogen-rich turbocharged were analyzed.It is found that the influence of the oxygen concentration distributions of the intake time,nitrogen-rich injection pressure and speed on the end of the compression and naturallyaspirated engine is basically the same, the nitrogen-enriched air intake applies toturbocharged diesel engine too.Through the study of the oxygen-rich intake-air control, the location and layout of thespace angle nozzles were analyzed in naturally aspirated diesel engine. The results showsthat oxygen concentration presents thinner in the middle and thicker in the edge in cylinderwhen the oxygen-rich nozzle in the position I and30°tangential the arrangement to the cylinder. In analyzing the effects of injection timing, it is found that the oxygenconcentration shows thinner in the middle and thicker in the edge after the injection process90°CA. In analyzing the impact of different oxygen-rich injection pressure, it was foundthat average mass fraction of oxygen increased with increasing injection pressure of theoxygen-enriched, when the injection pressure of the oxygen-enriched2atm, the oxygenconcentration presents thinner in the middle and thicker in the edge. In studying the effectsof different engine speed, when the engine speed is low speed, the oxygen concentrationpresents thinner in the middle and thicker in the edge in the end of the compression. As thespeed increases, the oxygen concentration gradient increases, changes is more significant.The oxygen-enriched air intake applies to turbocharged diesel engine too.