汽车(EGR)论文

汽车与环境保护初论摘要在现代文明的今天，汽车已经成为人类不可缺少的交通运输工具。

自从1886年第一辆汽车诞生以来，它给人们的生活和工作带来了极大的便利，也已经发展成为近现代物质文明的支柱之一。

但是，我们也应该看到，在汽车产业高速发展、汽车产量和保有量不断增加的同时，汽车也带来了大气污染，即汽车尾气污染。

汽车工业的发展和汽车数量的增加，使汽车排放对环境的危害日益加剧。

研究汽车排放污染的防治技术成了当前的重要课题。

本文分析了汽车排放污染与人类生存环境的关系，介绍了应从发动机燃烧、结构设计、燃料提供等技术及加强车辆维修保养、开发新型环保汽车等措施着手，控制汽车排放，减少大气污染。

关键词：污染物成分，危害控制，尾气净化。

第1章绪论在车水马龙的街头，一股股浅蓝色的烟气从一辆辆机动车尾部喷出，这就是通常所说的汽车尾气。

这种气体排放物不仅气味怪异，而且令人头昏、恶心，影响人的身体健康。

在车辆不多的情况下，大气的自净能力尚能化解汽车排出的毒素。

但随着汽车数量的急剧增加，交通拥堵成了家常便饭，汽车本应具备的便捷、舒适、高效的优势逐渐被过多的车辆所抵消。

“汽车灾难”已经形成，由此带来的汽车尾气更是害人不浅。

据环保部门的研究结果，北京市机动车排放对大气污染物中CO、HC、NO 的分担率分别为63.4% 、73.5% 和46%；上海市中心地区机动车排放对大气中CO、HC、NO 的分担率分别为86%、96%和56%。

许多国家的大中城市的空气污染有五成以上来源于汽车所排出的废气。

英国空气洁净和环境保护协会曾发表研究报告称，与交通事故遇难者相比，英国每年死于空气污染的人要多出10倍。

此外，汽车尾气是光化学烟雾形成的主要原因，它的危害要更甚于汽车尾气。

因此，必须严格控制汽车的排放污染，研究汽车排放污染的防治技术也成了当前的重要课题。

第2章、汽车排放污染物的主要成分及其危害汽车排放的污染物主要是一氧化碳CO、碳氢化合物HC、氮氧化物NOx 和微粒(碳烟、铅化合物等)等，它们对人类造成了很大的危害：CO 是发动机中因空气供给不足或其他原因造成的不完全燃烧时所产生的一种无色、无味但有剧烈毒性的气体。

《废气再循环控制系统设计与研究》篇一一、引言随着汽车工业的快速发展，发动机的能效和排放标准成为了人们关注的焦点。

废气再循环（EGR）控制系统作为提高发动机性能和降低排放的重要技术手段，其设计与研究显得尤为重要。

本文旨在探讨废气再循环控制系统的设计原理、结构及其在汽车发动机中的应用，以期为相关研究与应用提供参考。

二、废气再循环控制系统概述废气再循环控制系统是一种通过将发动机排出的部分废气重新引入到发动机的进气管中，以降低燃烧室内的温度和压力，从而达到降低氮氧化物（NOx）排放的目的。

该系统通常由传感器、控制器、执行器等部分组成，共同完成废气的循环再利用。

三、废气再循环控制系统的设计原理废气再循环控制系统的设计原理主要包括废气检测、控制策略及执行机构。

首先，系统通过传感器检测发动机的转速、负荷、温度等参数，以及废气的成分和流量。

然后，根据检测到的参数，控制器制定合适的控制策略，如废气再循环的比例、时机等。

最后，执行机构根据控制策略的指令，控制废气再循环阀的开度，实现废气的循环再利用。

四、废气再循环控制系统的结构废气再循环控制系统主要由传感器、控制器、执行器三部分组成。

传感器负责检测发动机的各项参数及废气的成分和流量；控制器根据检测到的参数制定控制策略，并输出控制信号；执行器则根据控制信号的指令，控制废气再循环阀的开度。

此外，系统还包括一些辅助设备，如冷却器、过滤器等，以保证废气再循环的效率和可靠性。

五、废气再循环控制系统在汽车发动机中的应用废气再循环控制系统在汽车发动机中的应用广泛，其优点在于能够降低NOx排放，提高发动机的能效。

通过将部分废气引入进气管，可以降低燃烧室内的温度和压力，从而减少NOx的生成。

同时，废气中的氧气含量降低，有助于提高燃油的燃烧效率。

此外，废气再循环控制系统还可以与其他排放控制技术相结合，如三元催化器等，进一步提高发动机的排放性能。

六、结论废气再循环控制系统是降低汽车发动机排放、提高能效的重要技术手段。

浅谈柴油机废气再循环（EGR）技术这一学期我们在老师的带领下认识了柴油机，令我印象最深刻的和让我最感兴趣的是废气再循环（EGR）技术，同时也是老师讲得最多的一个课题。

介绍随着日趋严重的环境污染问题的加剧，世界各国对发动机排放的法规越来越严格，从而促进了对低排放发动机的研究。

近年来，人们对发动机排放给予了高度重视，特别是废气再循环技术在柴油机中的应用对于降低排放污染物、达到环保要求，起到了良好的效果。

EGR是Exhaust Gas Re-circulation的缩写，即废气再循环的简称。

废气再循环是指把发动机排出的部分废气回送到进气歧管，并与新鲜混合气一起再次进入气缸。

由于废气中含有大量的CO2等多原子气体，而CO2等气体不能燃烧却由于其比热容高而吸收大量的热，使气缸中混合气的最高燃烧温度降低，从而减少了NOx的生成量。

工作原理EGR主要通过以下几方面发挥作用：EGR中的CO2和水蒸气大大增加了工质的比热容，同时废气的加入也稀释了原来混合气中的氧浓度，从而使燃烧速度变缓，使燃烧过程中的最高温度和平均温度都有所下降，破坏了NO生成的有利环境，从而大大降低NOX排放。

因为汽油机的负荷调节方式通常为量调节，所以在汽油机上应用EGR可以相应的增加进气量，EGR率的增加能降低汽油机在中低负荷工况下的节流损失，降低汽油机的燃油消耗率。

因为废气混入进气参与燃烧，会使发动机中的各个环节和参数发生变化，对发动机也会产生多方面的影响，而且影响是整体化的，必须总体考量。

分类有内部EGR和外部EGR两种系统内部EGR技术概述内部EGR技术结构简单，不需要外部设备，一般情况下通过改变配气相位就可以实现，等同于提高缸内的残余废气系数。

但是缸内的气流运动十分复杂，在不同工况下气流运动规律也不一样，所以这种实现废气再循环的方式很难控制EGR率；而且这种直接引入的方式，废气没有经过冷却，很大程度上的提高了混合气温度，使降低NOX排放的效果不够明显。

2024年汽车EGR系统市场前景分析引言汽车尾气排放一直是环境保护的重要问题之一。

随着对环境保护的重视和对汽车性能的不断需求，汽车排放技术也在不断发展。

其中，EGR（废气再循环）系统被广泛应用于汽车尾气净化领域。

本文将对汽车EGR系统市场前景进行分析，探讨其发展前景和市场影响。

EGR系统的基本原理废气再循环系统是一种通过将一部分废气重新引入汽车发动机的方法，以降低排放尾气中的有害物质含量。

其基本原理是将部分废气重新引入发动机燃烧室进行再燃烧，降低燃烧温度，减少氮氧化物（NOx）的生成。

一般而言，EGR系统由EGR阀、EGR冷却器和EGR传感器等组成。

EGR阀控制废气流量的大小，EGR冷却器通过降低废气温度来增加废气的密度，从而提高废气的再循环效率。

EGR传感器用于监测废气的温度和流量，以保证EGR系统的正常运行。

汽车EGR系统市场现状目前，全球汽车EGR系统市场正在快速发展。

主要原因有以下几点：1.环保要求的提高：各国对汽车尾气排放的标准越来越严格，对汽车制造商提出了更高的环保要求。

EGR系统能够有效降低NOx的排放量，符合环保标准。

2.节能减排的需求：EGR系统的应用能够降低汽车燃油消耗，提高燃烧效率，从而实现节能减排的目的。

这符合汽车行业的可持续发展趋势。

3.技术成熟度的提升：随着技术的不断进步，EGR系统的设计和制造已经相对成熟，具备较高的可靠性和稳定性。

这为其在汽车市场的应用提供了保障。

汽车EGR系统市场前景汽车EGR系统市场具有广阔的发展前景。

以下是几个关键因素：1.政策支持：各国政府通过出台环境保护政策和法规来推动汽车尾气排放的降低。

政策的支持将促使汽车制造商在新车型上广泛应用EGR系统，推动市场的增长。

2.技术创新：随着科技的不断进步和发展，EGR系统的技术也在不断创新。

例如，采用高效的EGR冷却器和智能控制系统等，可以提高系统的性能和可靠性。

这些创新将进一步推动市场的发展。

3.新能源汽车市场：随着新能源汽车市场的快速崛起，对于传统燃油汽车的改造也变得日益重要。

汽车排放污染控制技术论文随着世界各国对汽车排放污染的法律法规越来越严格，汽车排放性能已作为汽车重要的综合性能指标之一。

下面是店铺整理的汽车排放污染控制技术论文，希望你能从中得到感悟!汽车排放污染控制技术论文篇一浅析现代汽车排放控制技术[摘要]本文从降低燃油消耗和燃烧优化、废气处理、排放监测三个技术角度介绍现代汽车排放控制技术,同时简要阐述了各排放控制技术的原理、特点及影响因素。

最后总结出现代汽车排放控制技术的发展方向。

[关键词] 排放控制燃油消耗废气处理排放监测发展方向一、前言保护环境与节约燃料已成为全球关注的重大事件,以发动机为动力的汽车是大气污染的主要来源之一。

排放的废气对大气污染构成严重影响,如CO2引起温室效应;HC在阳光的作用下与NO进行光化学反应,形成一种毒性较大的光化学烟雾。

因此汽车的废气排放控制受到各国政府、汽车制造商的进一步重视。

二、汽车排放控制解决的问题汽车运行时,废气排放主要由排气管产生,包括CO、HC、CO2 、NOX 等气体;对于柴油机而言,还包括颗粒物排放。

CO、HC、CO2 等气体含量较少且便于处理,废气排放控制主要解决汽车NOX和颗粒物的排放。

故本文主要介绍由排气管产生的NOX和颗粒物排放控制技术。

三、现代汽车排放控制技术现代汽车废气排放控制策略从技术角度分为三大方面:降低燃油消耗和燃烧优化、排放废气的处理和排放性能的监测,其对应技术如下所述。

1. 降低燃油消耗和燃烧优化降低燃油消耗和燃烧优化可以降低汽车的使用费用、减少国家对进口石油的依赖、节省石油资源;同时降低了汽车的废气排放,其具体实现方法如下所述。

(1)汽车外型优化,减轻车身质量。

汽车在行驶过程中,主要受到空气阻力和滚动阻力,减小空气阻力和滚动阻力可以有效降低燃油消耗。

汽车外形优化可以有效降低空气阻力系数CD值,从而减小空气阻力。

减轻车身质量则是减小滚动阻力的重要途径。

但随着质量的降低,汽车的安全性下降,因此需综合考虑从而获得最佳效果。

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环保汽车论文篇一不仅不用油，而且车还可以提供家一样的感觉，车里的设备应有尽有，还有无线网络呢！车的电能是地面上的尘土转换成的，过多的电会存起来备用。

为了防止人们按喇叭产生噪音，车上有一个感应系统，只要有一定的车距，车就告诉前面的车“注意车距”，这样就没有噪音了。

一到上班高峰期，那个景象真是“车山车海”了，为了防止交通堵塞，我的轿车有一种超级装置，可以一下子到你想要去的地方，这样晚走一回也不会迟到。

为了防止被盗，我的车有指纹识别系统，可以一下识别主人和坏蛋，如果是坏蛋，一下子就能识别出来，并马上报警，警察会立即赶来，并用车上的网把下偷抓住，坏蛋自然就被抓住了。

为了防止交通危险，我的车可以打开保护膜，收上轮子，盖上盖子，就可以进入水中了，车上还可以打开氧气收集系统，可以收集水利的空气供主人呼吸。

这就是未来的环保汽车，希望能被人们创造出来。

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环保汽车论文篇二汽车给人带来了方便，但同时尾气也给人到来了麻烦。

为此我要发明一种环保香尾气汽车。

这种车远看和一般的车没什么两样，走近才会发现这种车没有排气管，只在车尾有几个蜂巢状的小孔。

人们不禁产生疑问，那么尾气是怎样处理的呢?后部的几个孔又是干什么的呢?原来汽车尾气通过在车内的一根管道一直来到行李箱中的一个大箱子里。

《废气再循环控制系统设计与研究》篇一一、引言随着汽车工业的快速发展，汽车尾气排放问题日益严重，对环境和人类健康造成了严重影响。

为了减少汽车尾气排放，废气再循环控制系统（EGR系统）被广泛应用于现代柴油发动机中。

EGR系统通过将部分废气重新引入到发动机的燃烧室中，降低氮氧化物（NOx）的排放，从而达到环保减排的目的。

本文将对废气再循环控制系统的设计与研究进行详细的探讨。

二、EGR系统的工作原理与组成EGR系统主要由传感器、执行器、控制单元以及相关管道组成。

其工作原理是通过传感器检测发动机的工况，将信号传输至控制单元，控制单元根据工况调整EGR阀的开度，从而控制废气再循环的比例。

1. 传感器：包括进气温度传感器、进气压力传感器、氧气传感器等，用于检测发动机的工况和废气的成分。

2. 执行器：EGR阀是EGR系统的核心执行器，通过调整其开度来控制废气的再循环比例。

3. 控制单元：接收传感器传递的信号，根据预设的算法计算出最佳的EGR阀开度，并发出控制指令。

4. 相关管道：将废气从发动机排气管引入到进气系统中，实现废气的再循环。

三、EGR系统的设计EGR系统的设计需要考虑多个因素，包括发动机的工况、废气的成分、系统的可靠性等。

下面将从几个方面介绍EGR系统的设计要点。

1. 传感器布局：传感器的布局应考虑到检测的准确性和响应速度，以及安装的便捷性和可靠性。

2. EGR阀的选择与安装：EGR阀应具有响应速度快、调节范围广、耐高温等特点。

同时，其安装位置应考虑到废气的流动路径和系统的布局。

3. 控制策略的制定：根据发动机的工况和废气的成分，制定合适的EGR控制策略，确保系统在各种工况下都能实现最佳的废气再循环比例。

4. 管道设计：废气再循环的管道应考虑到系统的布局、流动阻力、耐高温等因素，确保废气能够顺利地引入到进气系统中。

四、EGR系统的研究EGR系统的研究主要围绕提高系统的性能、降低排放、提高可靠性等方面展开。

400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A.Tel: (724) 776-4841 Fax: (724) 776-5760SAE TECHNICAL PAPER SERIES2000-01-0224Experimental and Numerical Investigation on the EGR System of a New Automotive Diesel EngineE. MattarelliUniversity of Modena and ReggioG. M. BianchiUniversity of BolognaD. IvaldiVM Motori – Detroit DieselReprinted From: In–Cylinder Diesel Particulate and NOx Control 2000(SP–1508)SAE 2000 World CongressDetroit, Michigan March 6–9, 2000The appearance of this ISSN code at the bottom of this page indicates SAE’s consent that copies of the paper may be made for personal or internal use of specific clients. This consent is given on the condition,however, that the copier pay a $7.00 per article copy fee through the Copyright Clearance Center, Inc.Operations Center, 222 Rosewood Drive, Danvers, MA 01923 for copying beyond that permitted by Sec-tions 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for creating new collective works,or for resale.SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Customer Sales and Satisfaction Department.Quantity reprint rates can be obtained from the Customer Sales and Satisfaction Department.T o request permission to reprint a technical paper or permission to use copyrighted SAE publications in other works, contact the SAE Publications Group.No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher.ISSN 0148-7191Copyright © 2000 Society of Automotive Engineers, Inc.Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the paper if it is published in SAE T ransactions. For permission to publish this paper in full or in part, contact the SAE Publications Group.Persons wishing to submit papers to be considered for presentation or publication through SAE should send the manuscript or a 300word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE.Printed in USAAll SAE papers, standards, and selected books are abstracted and indexed in the Global Mobility Database2000-01-0224 Experimental and Numerical Investigation on the EGR Systemof a New Automotive Diesel EngineE. MattarelliUniversity of Modena and ReggioG. M. BianchiUniversity of BolognaD. IvaldiVM Motori – Detroit Diesel Copyright © 2000 Society of Automotive Engineers, Inc.ABSTRACTIn this paper an integrated experimental and numerical approach is applied to optimize a new 2.5l, four valve, turbocharged DI Diesel engine, developed by VM Motori. The study is focused on the EGR system.For this engine, the traditional dynamometer bench tests provided 3-D maps for brake specific fuel consumption and emissions as a function of engine speed and brake mean effective pressure. Particularly, a set of operating conditions has been considered which, according to the present European legislation, are fundamental for emissions. For these conditions, the influence of the amount of EGR has been experimentally evaluated.A computational model for the engine cycle simulation at full load has been built by using the WAVE code. The model has been set up against experiments, since an excellent agreement has been reached for all the relevant thermo-fluid-dynamic parameters.The simulation model has been used to gain a better insight on the EGR system operations. Furthermore, the influence of the most important geometric parameters (EGR valve seat diameter, intake manifold throttle diameter) on the amount of recycled gas for a few critical operating conditions has been investigated.INTRODUCTIONA new generation of D.I. Diesel engines is setting the standards for automotive applications. These engines are turbocharged, and equipped with sophisticated high pressure injection systems. Furthermore, four valve technology is becoming more and more diffused. The enhancement of performance in terms of torque, fuel consumption and noise level has been dramatic in comparison to previous engines [1-6].One of the most critical issues of D.I. Diesel engines is the NOx control, in order to meet increasingly strict requirements. Exhaust Gas Recycle (EGR) is one of the more promising strategy to reduce these gas emissions, directly within the cylinder. EGR lowers the oxygen content, the combustion speed, the peak temperature at the flame front and consequently the NOx emissions [7-9]. When the amount of recycled exhaust gas is high, the increased temperature of the charge delivered to cylinder reduces the EGR benefit. This drawback can be canceled by cooling the recycling gas.In order to comply with the regulations on exhaust gas emissions, a new engine must be submitted to a long calibration process. A basic set-up of the engine is made at the dynamometer steady bench, at full load for every engine speed. The next step is a first specific calibration, also under steady operations, aimed to the vehicle which will be equipped with the engine.Considering a Common Rail injection system, the main parameters to be set-up for gas emissions are: fuel injection timings (main and pilot), injection pressure and amount of fuel in the pilot injection. EGR rate is a further parameter to optimize. The operating conditions which are considered at the dynamometer depend on the Legislation to be complied with. T o meet the European regulations (EURO 3 and EURO 4), VM Motori considers the set of steady conditions occurring during the European Driving Cycle, which are listed in table 1.The ensemble of conditions in table 1 covers about two thirds of the total time spent for the European Driving Cycle.For each condition, the injection parameters and the EGR rate are optimized by means of an experimental campaign. As far as the EGR is concerned, the analysis is focused on the trade-off between NOx and Soot. The set of optimized operating points is the basis for an initial calibration of the ECU all over the test driving cycle conditions.Thermofluid-dynamic engine cycle simulations can provide a useful support to the above experimental activity. However, for a complex system such as a turbocharged engine, the simulation model must be carefully set up and validated before application. Only when a good degree of confidence in the model is reached, can numerical results be used to integrate experimental information.As far as the EGR is concerned, simulation is expected to provide a better insight of the system operations. Furthermore, simulation gives a great help for the optimization of the EGR system geometry. The most interesting parameters to be studied are: the EGR valve diameter and the effective area of the intake manifold at the junction with the EGR pipe. Both parameters influence the amount of recycled gas, depending on the operating conditions and the engine geometry. The diameter of the EGR valve must be chosen in order to provide the proper rate of recycling gas in all the operating conditions of the test driving cycle. Sometimes, the variation of the valve diameter does not suffice to meet the target values of EGR rate. In order to increase this rate, the effective area of the intake manifold can be reduced by means of a throttle plate valve, or a Venturi nozzle. The former device can be controlled by the ECU and it is quite expensive; the latter is simple but it reduces the air flow rate even when the EGR valve is closed. THE ENGINE GEOMETRYThe engine is a turbocharged, intercooled, D.I. Diesel engine, 4 cylinder-in-line. It has a total displacement of 2,499 cc and four valves per cylinder. A picture is shown in figure 1, while the basic engine parameters are listed in table 2.Figure 1.The VM CR2516 engineThe VM engine lay-out is characterized by small intake and exhaust plenums, and short manifolds.T able 1.Set of steady conditions in the EuropeanDriving Cycle considered by VM at thedynamometer bench.Velocity[km/h]GearA idle neutralB32IIC35IIID15IE50IVF50IIIG70VH100VI120VT able 2.Basic engine parametersStroke [mm]94Connecting rod length [mm]163Intake valve diameter [mm]30.4Exhaust valve diameter [mm]28.9Compression ratio18.5:1Compressor inlet diameter [mm]46Compressor outlet diameter [mm]36T urbine inlet diameter [mm]45T urbine outlet diameter [mm]45IVO [c. a. deg.]14 BTDCIVC [c. a. deg.]44 ABDCEVO [c. a. deg.]62 BBDCEVC [c. a. deg.]32 A TDCEach intake manifold is split into two different ducts, one for each valve. The former is short and helical in order to force the flow to rotate around the valve axis. The latter is longer and straighter. This solution allows to meet high values of swirl, with a good permeability.The exhaust system geometry, up to the turbine, is very simple. Eight primary ducts, one from each valve, concur with different lengths and shapes in a small junction, in front of the turbine inlet. Since the distance from the engine cylinders to the turbine is reduced, as well as the diameters of the manifolds, the flow entering the turbine is strongly pulsating.The Common Rail injection system, by Bosch, brings the fuel pressure up to 1350 bar. The five-hole injectors are placed exactly in the center of the cylinder bore. Thanks to the shape of the bowl, optimized for the Common Rail injection features [10], the combustion chamber is particularly compact and efficient.The boost pressure is limited to the value of 2.3 bar by a waste-gate valve, integrated in the turbine housing. It is a diaphragm driven poppet valve, operated by the pressure difference between the intake plenum and the ambient. The engine is also equipped with an EGR valve, placed in the middle of the exhaust plenum. This valve controls the flow trough a duct connecting the exhaust to the intake system. As with the waste-gate, the poppet valve is driven by a diaphragm, separating two chambers at different pressures. While in one chamber the ambient pressure acts, in the other chamber a variable suction can be enforced. This suction is created by a vacuum pump, and is modulated by a three-way rotating valve. The ECU controls the duty cycle by which the 3-way valve is operated.For the experimental set-up of the simulation model, the engine has been operated at the dynamometer at constant speed and full load. The equivalence ratio is kept between 0.7 and 0.9. At low engine speed, up to 2200 rpm, a pilot injection precedes the main in order to reduce combustion noise and fuel consumption. The advance of the pilot injection varies between 30 and 40 crank angle degrees, while for the main injection, the advance goes from 7 to 17 c.a. deg. No catalyst or soot trap is present: the equivalent exhaust back-pressure is given by a butterfly valve lodged in the terminal pipe. THE FLUID DYNAMIC MODELEngine simulations are performed by using WAVE, a computer-aided engineering code licensed by Ricardo Software, Inc., Burr Ridge, IL. The code analyzes the dynamic of pressure waves, mass flows and energy losses in ducts, plenum and intake and exhaust manifolds of the engine. It also provides a fully integrated treatment of time dependent fluid dynamics and thermodynamics by means of a one-dimensional finite difference formulation, incorporating a general thermodynamic treatment of working fluids (air, air-hydrocarbon mixtures, products of combustion ). The code can model general networks of pipes, volumes and junctions in terms of a set of building blocks which include: constant area or conical pipes or ducts, passages with abrupt changes of area, junctions of multiple ducts, elbows, orifices and plenum, terminators such as infinite plenum (ambient), etc. Engine cylinders, turbocharger turbine and compressor can be attached to the pipe network to serve as the sources or absorbers of pulsating flows [11].The lay-out of the fluid-dynamic model developed for the VM engine is presented in figure 2. The model is made up of 98 simple junctions between two ducts, 8 junctions of multiple ducts, two ambient terminations, one compressor, one turbine, 4 cylinders and 119 constant area or conical ducts. Each engine component, particularly the compressor and the turbine, requires a specific strategy in order to be modeled. A detailed account on the modeling guidelines is beyond the scope of this paper, and can be found elsewhere [11-13]. Thus, only a few specific subjects will be presented in the rest of this section.The main experimental data used to build the simulation model are listed below.•T urbine and compressor steady maps, provided by the turbocharger manufacturer.•Discharge coefficients vs. lift for intake and exhaust valves (evaluated at a steady flow bench)•Amount of fuel injected at each operating condition (measured during the dynamometer test)•Heat release vs crank angle at each operating condition (evaluated from the pressure traces within the cylinder).•Friction mean effective pressure at each operating condition (difference between indicated and effective mean effective pressure)•Mean pressure at the compressor outlet at each operating condition•Mean pressure and temperature drop across the intercooler.•Mean back-pressure of the exhaust system downstream the turbine.As far as the discharge coefficients of the exhaust valves are concerned, particular care has been devoted to 'correct' the values before entering them in the simulation. A full account on the reasons and the procedure of this correction is given in [14].Figure 2. Layout of the engine computational model.Additional time has been spent also to determine the values of friction mean effective pressure. The indicated mean effective pressure, imep, has been evaluated as the algebraic sum of two in-cylinder pressure trace integrals. The former is made over the pressure experimentally measured during the compression and expansion strokes. The latter applies to the pressure trace computed during simulation of the intake and exhaust strokes.The waste-gate valve has been modeled as one cylindrical duct by-passing the turbine. The effective area of this duct is entered at each operating condition, in order to meet the experimental boost pressure. It has also been imposed that the valve be closed below the engine speed of 1800 rpm, at full load.The EGR is active only at partial load. Then, the numerical model has been set up versus experiments without the EGR valve.VALIDATION OF THE SIMULATION MODEL Figures 3-6 present a comparison between experimental and computational results, both obtained for the engine operated at full load, and steady conditions, and for several engine speeds from 1000 to 4200 rpm.Figure 3 presents the comparison for mean gas pressure and temperature against engine speed, in four important locations of the intake and exhaust system: compressor outlet, intake plenum, turbine inlet and turbine outlet. The agreement is very good.In figures 4-6 a comparison is made in terms of engine performance: air mass flow rate, brake mean effective pressure, brake specific fuel consumption. Only a slight error (less than 4%) can be observed for the air flow rate. Otherwise, the simulation model shows an excellent degree of accuracy.EGR EXPERIMENTAL CALIBRATIONThe basic map of EGR rate versus operating conditions for the test driving cycle has been made at the dynamometer steady bench. The operating conditions considered are those listed in table 1. For the specifically considered vehicle, the operating conditions in terms of Brake Mean Effective Pressure (BMEP) and engine speed are shown in table 3.Engine CylinderCompressorTurbineAmbient terminationSimple junctionComplex junctionComplex junctionT able 3.Operating conditions occurring in the European Driving Cycle for a vehicle equipped with theVM engine (see also table 1)Engine Speed [rpm]BMEP [bar]A8400.37B2085 1.6C1465 1.9D1904 2.0E1525 2.5F2100 2.6G1635 3.8H2345 5.5I2775 6.3(gas pressure and temperature in four locations of the engine)Figure parison between experimental andcomputational air flow rateFigure parison between experimental andcomputational Brake Mean Effective Pressure(BMEP).Figure parison between experimental andcomputational Brake Specific FuelConsumption (BSFC).The engine is rigged as for the traditional test at full load. Therefore, no device for exhaust gas after-treatment is present. The experiments have been carried out for two configurations of the EGR system, with and without cooling.As an example of this experimental activity, figure 7 presents NOx and soot emissions against EGR rate in four points (E, G, H and I), without recycle cooling.The EGR rate is defined as:(1)where is the mass flow rate of recycled exhaust gas, while is the mass flow rate of air delivered by the engine.Since the direct measure of the recycling flow rate is very difficult, another definition of EGR rate has been used:(2)where is the delivered air without EGR,while is the correspondent value with EGR. The two definitions would be equivalent if the total mass of fresh air and exhaust gas trapped within the cylinder were constant, with or without EGR. As it will be shown in the following, this condition is not verified. However, EGR%2 is a reliable index of the amount of exhaust gas which is recycled.From figure 7 it is clear that, as the EGR rate increases, the NOx emissions decreases, while the soot (measured in Bosch Smoke Unit, BSU) presents the opposite trend. The EGR rate has about no effect on brake specific fuel consumption, and little one on HC and CO emissions. The only exceptions for HC and CO have been observed in the operating points H and I, where the increasing of the EGR rate produces a sensible reduction of these emissions.The recent experience in VM suggests that values of soot up to 1.0 BSU can be generally tolerated during the steady simulation of the driving cycle. This value is consistent with the Particulate Matter (PM) limit of 0.05 gr/Km enforced by the imminent European regulation (called EURO3). It must be noted that, after the oxidation catalytic converter, PM emissions are expected to be reduced by as much as 50% (and visible smoke by even more). Therefore, the optimum value for the EGR rate is taken in order to stay just below the smoke limit of 1.0 BSU.&mEGR&mAIR()&/_m w o egrAIR()&m egrAIRFigure 7.Experimental values of NOx and Soot plotted against EGR rate, for a few steady operatingconditions. No recycle cooling.The trade-off for this engine is presented in figure 8. Without EGR cooler, the values of optimum EGR rate, defined by (2), goes from 0 at operating condition G, to 40% at A. With EGR cooler, optimum rates slightly change. The maximum value is 45%, at A.Figure 9 shows the percent reduction of the NOx emissions for all the operating conditions, with the optimized EGR rates shown in figure 8. Without cooling, an average reduction of 28.3% is achieved. With cooling, this figure increases to 33.5%.The maximum benefit is obtained at idle (A): without cooling there is a 55% decrease, while with EGR cooler the reduction is 64%. Very important for the European Driving cycle is the improvement of NOx emission at I. Here, EGR cooling is more effective for lowering NOx (42% against 25%). Figure 8.Optimum values of EGR rate for the steady operating conditions of the European DrivingCycle.Figure 9.Percent reduction of NOx with EGR, in the European Driving cycle steady conditions. NUMERICAL ANALYSIS OF THE EGR SYSTEM After the validation at full load, the engine simulation model has been used to gain a better insight of the EGR system operations. A first analysis has been carried out by varying the effective area of the EGR port. The four operating conditions E, G, H, and I, already presented in tables 1 and 3, have been considered. The waste-gate valve is closed. The port controlled by the EGR poppet valve has a seat diameter of 24 mm. The recycled gas is not cooled.The heat release law has been determined from the pressure trace at partial load, without EGR. Consequently, the analysis can not take into account the influence of exhaust gas in the trapped charge on combustion.Figures 10-17 present, at the four operating conditions, the influence of the EGR valve area ratio. The area ratio is intended as the ratio of the effective area of the port to the area of the valve seat. Figures 10 and 11 show the mass flow rate through the air filter and the EGR duct, respectively. As the area ratio increases, the delivered air reduces up to about 50%, while the amount of recycled gas builds up. The numerical dimension of the air flow rate is about one order higher than that of the recycle. Figures 12 and 13 present the amount of EGR according to the two definitions given in the previous section. Although the numerical values are quite different, the curves for EGR%1 present the same trend of the correspondent curves of EGR%2. Values of EGR%1 are usually lower than EGR%2’s (about one half), the only exception being operating condition E. The values of EGR rate are strongly dependent on the operating conditions. No evident correlation can be found to relate engine speed and load to EGR rate.In a turbocharged engine, the EGR valve at partial load works like the waste-gate, which, on the contrary, is usually closed. Since a part of exhaust gas is recycled before entering the turbine, the turbocharger speed reduces. As a consequence, also the boost and the turbine inlet pressure go down (see figures 14 and 15). The effect is more evident at high load. The difference between exhaust and intake pressure is almost constant as the EGR valve opens.The lowering of boost pressure strongly depends on the turbocharger geometry and the operating conditions. In this case, a 15% reduction can be observed for all the points, except for G. As a consequence, both in-cylinder pressure and temperature decrease, with positive effects on NOx emission.Figure 16 shows the Pumping Mean Effective Pressure (PMEP) versus area ratio. As the EGR valve opens, the amount of work spent to deliver and exhaust the gas lowers, particularly at high load (conditions H and I). This is the consequence of the flow rate reduction, and it can counterbalance the worsening of combustion. As far as combustion is concerned, in figure 17 it is interesting to observe that the air to fuel ratio never goes under the value of 25. Therefore, also in the worse conditions, the air availability with EGR is higher than that at the same speed and full load. This fact justifies the high tolerance to EGR of turbocharged Diesel engines.The choice of the EGR valve dimension depends on the rate of exhaust gas to be recycled at the operating conditions of interest. A numerical analysis has been carried out by WAVE to assess the influence of the valve seat diameter on the maximum amount of recycle that can be achieved. The duct connecting the exhaust to the intake system has a constant diameter of 28mm, while the valve seat diameter is varied from 10 to 28 mm. The simulation model, as well as the operating conditions, are the same as in the previous analysis.The main result of this analysis is shown in figure 18. As expected, the EGR rate (defined according to eq. 2) increases monotonically with the valve seat diameter at all the operating conditions, except for G, where the amount of EGR has a maximum at 24mm, then goes down. When comparing figure 18 to figure 8, it can be observed that values of EGR valve diameter greater than 15 can provide the target rate of recycle at all the considered operating conditions.The amount of recycled gas can be raised by throttling the intake manifold at the junction with the EGR duct, by means of a butterfly valve. The influence of the throat diameter has been analyzed by simulation. The usual four operating conditions (E, G, H and I) are considered. The EGR valve seat diameter is 24 mm, and the valve is kept wide open. The butterfly valve is modeled as a restriction with a diameter correspondent to the throat section to be analyzed. As in the previous analyses, the heat release law does not account for the exhaust gas recycle.Figure 18.Influence of the EGR valve seat diameter on the exhaust gas recycle (wide open position)for a few steady operating conditions. Figures 19 and 20 illustrate the air and EGR flow rate versus the intake throat diameter. At wide open throttle, the maximum value of the diameter is 55 mm. As the butterfly closes, the air rate decreases, while the EGR rises. The effect in terms of EGR rate is shown in figures 21 and 22, according to both the definitions given in the previous section.It is interesting to observe that the EGR rate increases only for strong throttling (from 55 to 40 mm EGR is about constant). For this reason, it is not recommended to install a Venturi nozzle in place of a throttle plate. The diffuser should be very long in order to drive the flow from the throat to the much bigger pipe section. Furthermore, at full load, the Venturi nozzle would be a severe limitation to the engine breathing capabilities.Since the intake throat diameter controls the mass flow rate, it also influences the turbocharger speed. As the air decreases, the turbocharger slows down: the balance position is found for lower values of turbine inlet pressure, as well as for compressor boost pressure (see figures 23 and 24).Figure 25 shows the values of PMEP, which are very low also for maximum throttling. The BSFC should not be influenced by this parameter. Finally, in figure 26, the air to fuel ratio is plotted against intake throat diameter. Despite the high value of recycle, the amount of air available for combustion is always higher than the counterpart at full load.CONCLUSIONA new 2.5l, four valve, turbocharged DI Diesel engine, developed by VM Motori has been studied by means of an integrated experimental and numerical approach.In order to comply with the imminent European Legislation on pollutant emissions (EURO 3), the engine is equipped with an EGR system. The management of the EGR valve requires a careful experimental calibration all over the operating conditions scheduled in the test driving cycle. A first set-up was made by VM at the dynamometer steady bench, considering all the steady conditions occurring in the driving cycle.The experiments have been carried out for two configurations of the EGR system, with and without cooling. EGR cooler demonstrated to be effective for improving NOx emissions, particularly at high load.The optimization of the EGR rate produced an important reduction of NOx emissions at the European driving cycle steady conditions. Without cooling, the average reduction is 28.3%. With cooling, this figure increases to 33.5%. This result is obtained without overcoming the smoke limit (enforced at 1.0 BSU, from the VM experience). No relevant effect has been observed on fuel consumption and other gas emissions.Engine cycle simulations by using WAVE provided a useful support to the experimental activity. Before performing the numerical analysis on the EGR system, the simulation model was set up and validated against experimental data at full load. An excellent agreement was achieved which justified a high degree of confidence in the computational results.A turbocharged engine with EGR is a very complex system from a fluid-dynamic point of view. No evident correlation can be found to relate engine speed and load to EGR rate. The EGR valve works like a waste-gate, reducing the turbocharger speed, the boost pressure, and the gas flow rate through the intake valve. For all the analyzed operating conditions with EGR, the air to fuel ratio was found higher than the correspondent value at full load. This fact justifies the high tolerance to EGR of turbocharged Diesel engines.The diameter of the EGR valve seat is a fundamental parameter for controlling the amount of recycle. For this engine, a proper choice of this dimension sufficed to achieve the target value of recycle. However, the EGR rate can be raised by throttling the intake manifold at the junction with the EGR duct, by means of a throttle plate or a Venturi nozzle. The latter must be discarded for this engine since, at full load, it would be a permanent and severe limitation to the engine breathing capabilities. ACKNOWLEDGMENTSThe authors wish to acknowledge Ricardo Software, Burr Ridge, IL, for the use of the WAVE code, granted to the University of Modena.A special thanks to Alessandro Mazza for the quality and large amount of work performed at the dynamometer bench.Stefano Fontanesi and Luca Montorsi are gratefully acknowledged for the good work performed during their degree thesis.Work performed with the financial support of the National Research Council (CNR).REFERENCES1.Morello, L., Rovera, G.,”Global approach to the fueleconomy improvement in passenger cars”.International Symposium: Powertrain technologies for a 3-litre-car. November 4-5, 1996. Certosa di Pontignano. Italy.2.Bernard, L., Occella, S., Vafidis, C.,”Potential of the4-cylinder small DI diesel engine concept”.International Symposium: Powertrain technologies for a 3-litre-car. November 4-5, 1996. Certosa di Pontignano. Italy.3.Foulkes, D., T abaczynski, R., Boggs, D., Schulte, H.,Hermann, H. O., Bartunek, B.,”Small DI diesel engines for high fuel economy vehicles”. International Symposium: Powertrain technologies for a 3-litre-car.November 4-5, 1996. Certosa di Pontignano. Italy. 4.Cichocki, R., Ospelt, W.,”T echnologies for futureHSDI passenger car diesel engines” International Symposium: Powertrain technologies for a 3-litre-car.November 4-5, 1996. Certosa di Pontignano. Italy. 5.Krieger, K., Hummel, K., Ricco, M.,”Potential of CRsystem for DI passenger car engines”. International Symposium: Powertrain technologies for a 3-litre-car.November 4-5, 1996. Certosa di Pontignano. Italy.。

汽车方面的毕业论文题目：汽车尾气排放控制技术的发展与创新摘要随着汽车工业的蓬勃发展，汽车尾气排放对环境和人类健康的威胁日益凸显。

为应对这一挑战，汽车尾气排放控制技术的研究与创新显得尤为重要。

本研究综述了汽车尾气排放控制技术的现状与发展，特别关注了创新技术的探索与实践。

研究表明，传统的排放控制技术如三元催化转化器等在降低有害物质排放方面发挥了重要作用，但随着环保法规的严格化，其局限性也日益凸显。

为此，新型排放控制技术如颗粒物捕集器（DPF）和选择性催化还原技术（SCR）等被开发并应用于实际生产中，显著提高了排放控制效果。

基于此，本研究还深入探讨了创新排放控制技术的问世、实际运用与验证，以及其所具备的技术优势和面临的挑战。

这项创新技术依托先进的材料科学和催化化学原理，通过改良催化剂配方和结构设计，并辅以智能控制系统，实现对尾气排放的精确管控。

实验结果表明，该技术能大幅减少汽车尾气中有害物质的排放量，提升排放控制效果，具备颇高的催化转化效率和稳定性。

汽车尾气排放控制技术将朝着更高效、更环保、更智能化的方向发展。

政策法规的严格化和市场需求的变化将推动排放控制技术的不断创新和升级。

同时，新能源汽车的快速发展也将对排放控制技术产生重要影响，为排放控制技术的发展带来新的机遇和挑战。

本研究不仅为汽车尾气排放控制技术的研发和应用提供了参考和借鉴，也为未来排放控制技术的发展方向提供了有益的思考。

关键词：汽车尾气排放；排放控制技术；创新技术；发展趋势；环保法规目录摘要 (1)第一章引言 (3)1.1 汽车尾气排放的危害 (3)1.2 排放控制技术的重要性 (4)1.3 研究背景和目的 (5)第二章汽车尾气排放控制技术发展现状 (7)2.1 传统排放控制技术 (7)2.2 新型排放控制技术 (8)2.3 国内外技术对比 (9)第三章创新排放控制技术的探索与实践 (10)3.1 创新技术的提出 (10)3.2 实践应用与验证 (10)3.3 技术优势与挑战 (11)第四章排放控制技术的未来发展趋势 (13)4.1 技术发展动态 (13)4.2 政策法规影响 (13)4.3 市场需求与趋势 (14)第五章结论 (16)5.1 研究成果总结 (16)5.2 对未来研究的建议 (17)第一章引言1.1 汽车尾气排放的危害随着全球汽车工业的飞速发展，汽车尾气排放已逐渐成为环境污染的主要来源。

《EGR对点燃式甲醇发动机燃烧及排放影响的试验研究》篇一一、引言随着环保意识的增强和能源危机的日益严峻，汽车行业对新型、清洁和可持续能源的需求不断上升。

甲醇作为一种可再生的生物质能源，因其具有较高的辛烷值和优良的环保性能，越来越受到汽车工业的青睐。

然而，甲醇发动机的燃烧过程和排放控制仍面临诸多挑战。

其中，废气再循环（EGR）技术被认为是一种有效的改善发动机燃烧过程和降低排放的技术手段。

本文将就EGR对点燃式甲醇发动机燃烧及排放的影响进行试验研究。

二、试验材料与方法1. 试验设备本试验采用某型号的点燃式甲醇发动机作为试验对象，同时配备了EGR系统、燃料供给系统、测量及控制系统等设备。

2. 试验方法（1）设定不同的EGR率（0%、10%、20%、30%），分别对甲醇发动机进行燃烧和排放测试。

（2）利用先进的发动机测试设备，对发动机的燃烧过程、排放物进行实时监测和记录。

（3）分析EGR率对甲醇发动机的燃烧特性、动力性能以及排放物的影响。

三、试验结果与分析1. 燃烧特性随着EGR率的增加，甲醇发动机的燃烧过程发生了显著变化。

EGR率的提高使得燃烧过程的峰值压力和峰值放热率有所降低，燃烧持续期延长。

这表明EGR技术有助于改善甲醇发动机的燃烧过程，降低燃烧噪声和振动。

2. 动力性能在EGR率较低时（如10%），甲醇发动机的动力性能基本保持不变。

然而，随着EGR率的进一步提高，发动机的动力性能出现了明显下降。

这主要是由于高EGR率导致发动机缸内氧气含量减少，从而影响了甲醇的充分燃烧。

3. 排放物影响（1）CO排放：随着EGR率的增加，CO排放量呈现出先降低后升高的趋势。

在适当的EGR率下（如20%），CO排放得到显著降低。

（2）HC排放：EGR技术有助于降低HC排放。

随着EGR 率的增加，HC排放量逐渐减少。

（3）NOx排放：EGR技术通过降低缸内最高温度，从而有效降低NOx排放。

随着EGR率的增加，NOx排放量显著减少。