Numerical Analysis Of Soot And NO_X Generation Process Of Diesel Engine With Chlorella Biodiesel Fuel

Chlorella is a kind of algae that grows widely in different waters.It has the advantages of high oil content,short growth cycle and wide distribution range.The development of Chlorella Biodiesel Fuel?CBF?is beneficial to resolve the contradiction between the shortage of biodiesel raw materials and the occupation of cultivated land resources in China.The existing research of domestic and foreign scholars mainly focuses on the preparation process of CBF,analysis of fuel characteristics,etc.,there are few studies on the combustion reaction kinetics model and the failure to grasp the precise flow field structure of the CBF combustion process restricts the application and promotion of CBF.To this end,this article will build a CBF model that is suitable for a variety of different reaction conditions and contains Soot and NO_X generation mechanisms.Establish a combustion model of 186FA diesel engine with CBF,and carry out the coupling calculation of CBF model and combustion model,reveal the detailed derivation process of Soot and NO_X in different combustion stages of diesel engine cylinders,provide a certain theoretical basis for the clean combustion of chlorella biodiesel.Main tasks as follows:?1?Constructed a simplified CBF model including Soot and NO_X generator sub-models.Using Directed Relation Graph with Error Propagation?DRGEP?,under different equivalence ratios,initial fuel temperature and initial reaction pressure,taking the main combustion products H₂O,CO₂ and OH as reference components,with a relative error of less than 5%,10%and 15%as the target,the CBF detailed model has been simplified and combined.And added different Soot and NO_X generation mechanisms to the combined model,got three new models?respectively denoted as JZP5%,JZP10%,JZP15%?,by comparing the predicted value of the ignition delay period between the new model and the original detailed model,its effectiveness was analyzed.The results show that,compared with the original detailed model,the new model has better prediction performance under high temperature reaction conditions.The maximum error is less than 3%.But the error is larger under low temperature reaction conditions,the maximum errors of JZP5%?434components,2003 reactions?,JZP10%?348 components,1768 reactions?,and JZP15%?318components,1579 reactions?were 4.8%,5.1%,and 5.8%.?2?Study the generation process of Soot and NO_X in the cylinder of CBF in different combustion stages.Using AVL-FIRE to build a combustion model of 186FA diesel engine with CBF,the coupling calculation of the simplified CBF model and the combustion model was carried out,Compare and analyze the calculated value and test value of cylinder pressure and heat release rate,The accuracy of the simulation is verified.Using coupled calculation and rate of production analysis?ROP?,the generation history of Soot and NO_X in the cylinder of CBF in different combustion stages was analyzed.The results show that the maximum error between the calculated value and the experimental value of the cylinder pressure and heat release rate are 4.4%and 7.6%,respectively,the accuracy of the coupling calculation is good.At the midpoint of burning,C₃H₅-A and MP2D generated by CBF will generate C₃H₃ and C₂H₂ through a series of reactions,these substances are then polymerized and cyclized to produce benzene;At the end of the combustion,hydrocarbons first produce C₃H₃,C₂H₂ and C₂H₃ through a series of cracking reactions,these substances are then polymerized and cyclized to produce benzene.Among them,OH,H,O and O₂are important participants in the production of benzene,C₂H₂ and C₃H₃ are important intermediate products common to benzene formed at the midpoint and end of combustion.C₂H₃ is an important intermediate product of benzene formation at the end of combustion,Controlling the generation of C₂H₂,C₃H₃,and C₂H₃ is beneficial to reduce carbon emissions.Research on the history of NO_X generation,at the midpoint of combustion,N₂ first generates NNH,NNH reoxidizes to produce NO and N₂O;at the end of the combustion,on the one hand,N₂ directly generates NO,NO is then oxidized to form NO₂.On the other hand,N₂ first generates NNH,NNH regenerates N₂O.Among them,OH,H₂,O and HO₂ are important participating substances in the production of NO_X,NH and NNH are important intermediate products that produce NO_X at the midpoint and end of combustion,respectively.Controlling the generation of NH and NNH is beneficial to reduce NO_X emissions.