柴油机SCR系统故障检测诊断箱的开发及试用

正柴油机用途广泛,是工程机械和各种车辆的主要动力源。国家相关法规对柴油机尾气污染物排放量要求越来越严格,仅凭机内净化技术难以达到尾气排放标准要求,必须采取机内净化技术与后处理技术相结合的措施,方可达到相关法规要求。1.开发诊断设备的重要性采用选择性催化还原(SCR)技术将是实施我国柴油机国Ⅳ排放标准的主要后处理技术。SCR系统主要由催化消声器、尿素罐、尿素喷射计量泵(简称尿素泵)、氮氧化物(NOx)传     

柴油机尿素品质传感器技术路线分析

随着环境问题的日益显现,环保部门制定了严格的排放法规,市场监管和检查也严格落实到位,尤其是到国六阶段[1][2],排放要求非常严苛,为此,柴油发动机均配备了SCR系统(Selective Catalytic Reduction选择性催化还原技术),以减少尾气中的NOX(氮氧化物)排放,其中SCR系统的添加剂就是车用尿素。车用尿素溶液为32.5%尿素和67.5%去离子水的高纯溶液,其浓度对车辆使用影响重大,直接影响车辆动力性、燃油经济性、排放合理性以及OBD监测要求,因此,需要对尿素浓度实施实时监测,检测尿素浓度的传感器就是尿素品质传感器,下文中将对尿素品质传感器作进一步分析。     

高压共轨柴油机DOC/POC/SCR后处理系统的开发研究

本文提出了对在用的高压共轨柴油机满足国Ⅴ排放法规的技术方案。它以32.5%的尿素水溶液为还原剂,采用本文提出的DOC/POC/SCR后处理系统,通过共轨柴油车的发动机台架试验,分析了ESC循环测试下NOx的排放浓度和负荷特性下NOx的排放浓度,结果表明:若仅采用单一的Urea-SCR后处理系统,共轨柴油机排气中的NOx浓度降至300ppm左右,转化率可达到75%,只能满足国Ⅳ的排放法规要求值;而采用本文提出的DOC/POC/SCR后处理系统后,共轨柴油机排气中的CO和HC净化效果显著,NOx浓度降至180ppm左右,转化率可达到85%完全满足了当前实施的国Ⅴ的排放法规,实现了对在用高压共轨柴油机后处理系统的技术升级。     

柴油机NO_X排放预测模型研究

选择催化还原法(SCR)作为柴油机尾气排放机外控制的有效方法之一,正得到不断的发展和推广应用。针对SCR技术中尿素喷射控制的难点,并结合系统部分输入已知的特点,提出了应用一种带有外部输入的线性/非线性自回归模型(GNARX模型),将净扭矩、增压机转速和油门踏板位置这3个序列作为模型外部输入,对柴油机氮氧化物(NOX)原机排放量做出预测预报。结果表明,GNARX模型对NOX原机排放量的建模预测精度高于GNAR和ARX模型,可为柴油机SCR系统尿素喷射控制提供了可靠的数据反馈。     

浅谈SCR后处理技术对柴油机排放的优化

柴油机的发明创造提高了生产力,推动了社会进步,同时也带来了以氮氧化物为主体的尾气污染,威胁着环境安全。本文讲述了SCR后处理技术对柴油机尾气的优化减排,从原理和装置结构分析其如何做到对柴油机尾气进行优化处理以及SCR系统的发展趋势。     

柴油机SCR尿素流量计的设计与试验

为准确快速检测柴油机SCR系统尿素喷射量,设计了尿素流量计的结构和信号处理电路,制定了尿素流量计结构和元器件参数的优化策略,并进行了参数最优匹配;对三款尿素喷射流量计进行了性能检测、尿素喷射量和NH3泄漏等测试试验.结果表明:优化后的尿素流量计线性度误差、灵敏度误差和输出信号误差率分别0.36％、0.30％和0.54％.证实了尿素流量计优化与控制策略的切实可行性;表明了设计的SCR系统尿素喷射流量计适合柴油机在线实时检测要求,为柴油机满足国Ⅳ排放标准提供了保障.     

MAN柴油发动机排气后处理系统概述

随着2030碳达峰越来越近,那么我国汽车排放要求必然会越来越严格,鉴于一些工程服务领域的特殊性,长时间内仍会以柴油机为主。目前柴油车为达到排放要求采用最多的就是上装选择性催化还原装置(SCR)技术,而该系统最重要的一点是需要添加尿素(AdBlue),若因SCR系统出现问题,轻则车辆功率下降,燃油消耗增大,排放有害物质增多,重则不能启动,故如何对SCR系统进行维护就显得格外重要。     

柴油机SCR瞬态参数采集处理与诊断系统

基于尿素SCR系统瞬态特性,开发了适合柴油机SCR瞬态参数的测试与诊断系统;采用DASYLab软件,编写了接口、标定与诊断程序,实现了SCR系统信号显示、存储与再现等功能;依据遍历跟踪与诊断程序,实现了对柴油机SCR系统瞬态特性参数的在线测试与诊断;依据柴油机瞬态测试循环法规,进行了柴油机SCR系统的NOx转化效率、尿素喷射量和NH3泄漏量等测试与诊断试验。结果表明:与标准的AVL测试系统(AVL CBE-Ⅱ气体排放分析与测试系统)相比,所研发的系统动态最大误差为2.05%,动态平均误差为0.82%,故障诊断精确率达到了98.6%,能满足柴油机SCR瞬态测试循环要求。     

尿素喷射管路对气助式尿素喷射装置性能影响研究

SCR系统是目前较为成熟的重型柴油机尾气后处理技术,其中尿素泵、尿素喷嘴是SCR系统的核心部件,与尿素喷射管路共同组成发动机尿素喷射系统,其喷射精度、雾化质量等性能直接影响柴油机SCR系统的NOx转化率和NH3泄露量。为了探究尿素喷射管路对气助式尿素喷射系统性能的影响,搭建发动机试验台架,使用不同规格的尿素喷射管进行ESC、ETC排放试验,并通过关键过程数据的对比分析,研究尿素喷射管对气助式尿素喷射系统性能的影响。试验结果表明,采用不同规格尿素喷射管能够影响空气辅助尿素喷射系统对NOx的处理效果以及氨气的泄漏量;尿素管路内径较粗,会影响尿素的正常喷射,导致ESC循环各工况点NOx尾气浓度不稳定,带来氨泄漏的增加,尿素喷射量较大的高负荷工况更加明显;喷射管长度较长会影响尿素喷射的瞬态响应性,适当减小尿素管长度有助于提高气助系统对NOx的转化效果、降低氨泄漏风险。搭建的常用气助式尿素喷射系统,使用内径3 mm,长度1.5 m以内的尿素喷射管最优。     

柴油机后处理加热系统故障检测方法研究

为了满足日益加严的排放法规要求,从国四阶段开始后处理技术采用SCR,通过向排气管中喷射尿素以减少发动机排放的氮氧化物。冬天或温度较低时,SCR系统需加热后方可正常喷射尿素。目前尿素泵及尿素管路均采用加热电阻元件进行电加热,当加热电阻元件发生故障时将不能实现对SCR系统的加热。为了实现SCR系统可正常加热,需要四个ECU针脚分别诊断四个加热电阻元件的开路或短路故障,而目前大部分ECU针脚资源有限无法满足诊断要求。因此,本文提供一种采用一个针脚分时诊断四个加热电阻元件的故障检测方法,通过台架试验证实该方法有效并可靠。     

Influence of the Rotational Charge Motion on the Processes of Nitrogen Oxide Formation and Nonstationary Heat Transfer in a Hydrogen Diesel

The concept of a hydrogen diesel with direct gaseous hydrogen injection, despite the obvious advantages as compared to a traditional diesel, is poorly explored. In this article, the problem of the determination of the rotational charge motion intensity value in a hydrogen diesel cylinder is first formulated and solved in order to establish the limits for the emission of nitrogen oxides and the heat loads on the main parts (on a piston) of a motor under the hydrogen combustion. These parameters, which determine the environmental characteristics and the thermal stress state of a hydrogen diesel, can be regulated by varying the advance angle of the hydrogen injection under the acceptable values of the performance parameters of a motor. The optimal values (in terms of minimizing the emission of nitrogen oxides and the heat loads) of the rotational charge motion intensity and the advance angle of the hydrogen injection were determined for the case of a one-cylinder hydrogen diesel.     

车用尿素溶液一体化气动供给系统设计

针对柴油机Urea-SCR系统需求,设计开发了一种车用尿素溶液一体化气动供给系统,该系统集成了尿素溶液的存储、计量喷射、雾化等功能。利用汽车压缩空气作为尿素溶液的驱动力及辅助雾化的动力来源,该供给装置具有结构简单紧凑、工作可靠、计量精确等优点。详细分析了系统的组成、工作原理、设计要求等内容,阐述了气动式SCR系统的结构,制作了供给系统的样机,并与重型柴油机进行了ESC和ETC联合试验。试验结果表明,该供给系统能根据柴油机的运转工况,喷入雾化良好、计量精确的尿素溶液,显著降低排气中的NOx浓度,使柴油机排放水平达到国IV法规要求,对实现SCR系统国产化具有重要意义。     

SCR技术在国内车用柴油机上的应用

选择催化还原技术（SCR）是降低车用柴油机NOx排放的机外措施之一。阐述了SCR技术的机理、系统组成及工作原理,介绍了国内车用柴油机SCR技术的研究情况及还需解决的问题。     

基于多目标优化的柴油机VNT–vEGR系统开发研究

为了在兼顾柴油机经济性和颗粒物排放的前提下,进一步降低氮氧化物(Nitrogen oxides,NO_x)排放以实现良好的柴油机综合性能,设计带文丘里管废气再循环系统的可变涡轮增压系统(Variable nozzle turbo+Venturi-exhaust gas recirculation,VNT+vEGR)。针对排气旁通阀涡轮增压(Wastegate,WG)柴油机原机,进行文丘里管废气再循环系统(Venturi-exhaust gas recirculation,v EGR)的设计和与可变涡轮增压器(Variable nozzle turbo,VNT)的匹配研究,并进行经济性、氮氧化物和颗粒物排放仿真计算研究。应用试验设计方法技术(Design of experiment,DoE)对VNT-vEGR系统进行多目标优化研究。研究结果表明,相比于配备排气旁通阀涡轮增压器的柴油机原机,对VNT-v EGR系统柴油机应用Do E进行多目标优化匹配后,欧洲稳态测试循环(European steady-state cycle,ESC)工况加权油耗值基本保持不变,氮氧化物加权排放量下降约49.5%,能够实现良好的综合性能。     

Study of performance and emission characteristics of IC engines by using diesel–water emulsion

Due to the shortage of petroleum products and its increasing cost, efforts are on to develop alternate fuels, especially diesel oil, for partial or full replacement. Also, internal combustion engines generate undesirable emissions during combustion process. The emissions exhausted in to the surroundings pollute the atmosphere and causes several problems. The emissions of concern are: unburnt hydrocarbons, oxides of carbon, and oxides of nitrogen (NO_X). Advanced diesel fuel formulations offer significant emission reductions to new and older in-use engines every time the fuel tank is filled. The addition of water to diesel fuel lowers particulate emissions by serving as diluents to the key combustion intermediates that lead to particulate formation. The incorporation of water also reduces NO_X emissions by lowering the peak combustion temperatures through high heat of vaporization. When using water blend diesel, the engine fuel system recognizes the liquid as diesel fuel because the water droplet is encapsulated within a diesel fuel. In this experiment, we have used single cylinder four-stroke engine and the water-blend diesel emulsion is used and the diesel emission test, emulsion emission test, and various gases has been analyzed; smoke meter test is also conducted for various rate of loads. The test results from the engine fuelled with water-blend diesel showed reduction in emissions as compared to that of engine fuelled with conventional diesel. The better emissions in the CI engine using water-blend diesel is due to the incorporation of water which reduces NO_X emissions by lowering the peak combustion temperatures. Water-blend fuel enhances fuel atomization by micro-explosion. The addition of water to diesel fuel lowers particulate emissions by serving as diluents to the key combustion intermediates that lead to particulate formation     

柴油发动机模拟排气试验台的研制

设计并建造了一个模拟多种柴油机尾气的试验台.试验台的热源由柴油燃烧提供,烟气的温度和流量由控制系统调节实现.试验台能够模拟出和实际柴油机工作时尾气特性(温度、压力、流量)相似的热烟气.模拟的柴油机尾气的试验台和SCR(选择性催化还原)系统相结合,可以降低试验成本,并使试验的可信度更高,为给定热源条件下SCR系统的设计提...     

Improving the ecological indices of a hydrogen diesel engine with direct gaseous hydrogen injection

A detailed survey of the operating process and formation of nitrogen oxides in the combustion chamber of a hydrogenous diesel has been carried out in three-dimensional space using a mathematical model verified by experimental data. The specific features of the thermophysical processes in the combustion chamber of the hydrogen diesel engine have been specified, providing the applicable ecological and efficient indices of a stationary hydrogen diesel engine.     

A study on the usability of biodiesel fuel derived from rice bran oil as an alternative fuel for IDI diesel engine

The world is faced with a problem of air pollution due to the exhaust emissions from automobile. Recently, lots of researchers have been attracted to develope various alternative fuels and to use renewable fuels as a solution of these problems. There are many alternative fuels studied in place of diesel fuel made from petroleum. Biodiesel fuel (BDF) is a domestically produced, renewable fuel that can be manufactured from vegetable oils, used vegetable oils, or animal fats. In this study, the usability of BDF, one of the oxygenated fuels as an alternative fuel for diesel engines was investigated in an IDI diesel engine. Emissions were characterized with a neat BDF and with a blend of BDF and conventional diesel fuel. Since the BDF includes oxygen of about 11%, it could influence the combustion process strongly. Therefore, the use of BDF resulted in lower emissions of carbon monoxide and smoke emissions with some increase in emissions of oxides of nitrogen. It is concluded that BDF can be utilized effectively as a renewable fuel for IDI diesel engines.     

A fuzzy logic urea dosage controller design for two-cell selective catalytic reduction systems

Diesel engines have dominated in the heavy-duty vehicular and marine power source. However, the induced air pollution is a big problem. As people's awareness of environmental protection increasing, the emission regulations of diesel-engine are becoming more stringent. In order to achieve the emission regulations, the after-treatment system is a necessary choice. Specifically, the selective catalytic reduction (SCR) system has been widely applied to reduce the NO_X emissions of diesel engine. Different from single-cell SCR systems, the two-cell systems have various benefits from the modeling and control perspective. In this paper, the urea dosage controller design for two-cell SCR systems was investigated. Firstly, the two-cell SCR modeling was introduced. Based on the developed model, the design procedure for the fuzzy logic urea dosage controller was well addressed. Secondly, simulations and comparisons were employed via an experimental verification of the whole vehicle simulator. And the results showed that the designed controller simultaneously achieved high NO_X reduction rate and low tail-pipe ammonia slip.