【作者】 孙超；

【导师】 毛功平；

【作者基本信息】 江苏大学 ， 动力工程（专业学位）， 2020， 硕士

【摘要】 小球藻是一种广泛生长于不同水域的藻类,具有油脂含量高、生长周期短、分布范围广等优点,发展小球藻生物柴油（Chlorella Biodiesel Fuel,CBF）,有利于解决我国生物柴油原料不足且占用耕地资源的矛盾。国内外学者现有研究主要集中于CBF的制备工艺、燃料特性分析等方面,对其燃烧反应动力学模型、燃烧污染物Soot和NO_X的生成机理等方面的研究较少,导致未能掌握CBF燃烧过程的精细流场结构,制约了CBF的应用和推广。为此,本文将构建适用于多种不同反应条件且包含Soot、NO_X生成机理的CBF模型,建立186FA柴油机燃用CBF的燃烧模型,并开展CBF模型与燃烧模型的耦合计算,揭示柴油机缸内不同燃烧阶段Soot、NO_X的详细衍生过程,为实现小球藻生物柴油的清洁燃烧提供一定的理论基础。主要工作如下:（1）构建了包含Soot和NO_X生成子模型的CBF简化模型。利用基于误差传播的直接关系图法（Directed Relation Graph with Error Propagation,DRGEP）,在不同当量比、燃料初始温度、初始反应压力条件下,以主要燃烧产物H₂O、CO₂和OH作为参考组分,以相对误差分别小于5%、10%和15%为目标,对CBF详细模型进行了简化和组合。并在组合模型中加入了不同的Soot、NO_X生成机理,得到了三种新模型（分别记为JZP5%、JZP10%、JZP15%）,通过比较新模型与原详细模型着火延迟期的预测值,对其有效性进行了分析。结果表明,相对于原详细模型,新模型在高温反应条件下的预测性能较好,最大误差小于3%,但在低温反应条件下的误差较大,JZP5%（434种组分,2003个反应）、JZP10%（348种组分,1768个反应）、JZP15%（318种组分,1579个反应）的最大误差分别为4.8%、5.1%和5.8%。（2）研究了CBF在不同燃烧阶段柴油机缸内Soot、NO_X的生成历程。通过AVL-FIRE软件构建了186FA柴油机燃用CBF的燃烧模型,开展了CBF简化模型与该燃烧模型的耦合计算,比较分析了缸内压力、放热率的计算值与台架试验值,验证了模拟的准确性。利用耦合计算和生成速率分析（Rate Of Production analysis,ROP）,分析了CBF在不同燃烧阶段柴油机缸内Soot、NO_X的生成历程。结果表明,缸内压力、放热率计算值与试验值的最大误差分别为4.4%、7.6%,耦合计算的准确度较好。在燃烧中点时刻,CBF生成的C₃H₅-A、MP2D经过一系列反应会分别生成C₃H₃、C₂H₂,这些物质再通过聚合和环化反应生成苯;在燃烧终点,多种碳氢化合物首先通过一系列裂解反应生成C₃H₃、C₂H₂和C₂H₃,这些物质再经过聚合和环化反应生成苯。其中,OH、H、O和O₂是生成苯的重要参与物质,C₂H₂、C₃H₃是燃烧中点和燃烧终点生成苯共有的重要中间产物,C₂H₃是燃烧终点生成苯的重要中间产物,控制C₂H₂、C₃H₃、C₂H₃的生成有利于降低碳烟的排放。对NO_X生成历程进行研究发现,在燃烧中点,N₂首先生成NNH,NNH再氧化生成NO和N₂O;在燃烧终点,一方面,N₂直接生成NO,NO再经过氧化反应生成NO₂,另一方面,N₂首先生成NNH,NNH再生成N₂O。其中,OH、H₂、O和HO₂是生成NO_X的重要参与物质,NH、NNH分别是燃烧中点和燃烧终点生成NO_X的重要中间产物。控制NH和NNH的生成有利于降低NO_X的排放。更多还原

【Abstract】 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.更多还原