不同海拔下国六柴油机性能试验研究EI北大核心CSCD

基于高原环境模拟试验台架,研究了不同海拔下国六柴油机全负荷和40%负荷工况下的动力性、经济性及排放特性,同时探讨了4 000 m海拔下发动机持续运行在低转速大负荷工况柴油机颗粒物捕集器(DPF)堵塞的可能性。结果表明:全负荷和40%负荷工况下随着海拔的上升,发动机的进气流量、空燃比、有效热效率,排气氧浓度、排气压力呈非线性减小,有效燃油消耗率、排气温度、NO排放呈不同幅度增加;动力性、经济性下降明显,排放性能恶化;全负荷工况对海拔的变化更加敏感,特别是低转速和高转速的性能降幅较大;国六柴油机在4 000 m海拔下持续运行在低转速大负荷工况,DPF内大量颗粒物沉积但再生困难,较短时间内被堵塞。     

DOC+CDPF+SCR对轻型柴油机排放特性的影响

为研究DOC+CDPF+SCR对轻型柴油机动力性、经济性、排放性的影响,以一台满足国五排放法规的轻型柴油机作为样机,加装DOC+CDPF+SCR后处理系统后进行了台架试验研究。结果表明:加装DOC+CDPF+SCR后处理系统对柴油机的动力性和经济性有一定影响,外特性下扭矩平均降幅为1.3%,负荷特性下燃油消耗率平均升幅为2.6%。DOC+CDPF+SCR能有效降低柴油机的NO_x,THC,CO以及颗粒物排放。DOC主导净化THC和CO,对颗粒物也有良好的减排能力;SCR主导净化NO_x,排气温度较低时转化效率不高;CDPF主导净化颗粒物排放,对中小粒径颗粒物的净化效率更高。PN和PM平均减排率分别为99.1%和96.6%。     

氧化催化器对柴油机排放颗粒物中无机盐组分影响的研究

为揭示氧化催化器(DOC)对柴油机颗粒物排放的影响,利用ELPI、电感耦合等离子体发射光谱法(ICP-AES)和离子色谱法(IC)对一款装有DOC的柴油机排放颗粒物数量浓度和无机盐组分的排放速率进行实验研究.结果表明:DOC后排放颗粒物的数量有所降低;但大多数无机盐组分排放速率都增加,且随负荷的升高而增大,其中,地壳元素的增长幅度大于人为元素;在大多数工况下硫酸根离子的排放速率增大,且随转速和负荷的增加而增大;硫酸根在颗粒物中的质量分数也增大,且随负荷的升高而增大.     

基于法规的柴油发动机颗粒物数量排放测试研究EI北大核心CSCD

采用满足欧Ⅵ颗粒数量(PN)测试要求的AVL489颗粒计数器,对3台不同机型的柴油机进行了ESC,ETC和WHTC循环试验,并测量了PN排放情况。结果表明:在不同机型和不同试验循环下,PM(颗粒物质量)和PN排放的相关性较高;DOC+POC后处理可有效降低PN排放;热起动WHTC循环的PN排放比冷起动高,但差异很小;PN排放随转速的升高和负荷的加大而增高。     

基于法规的柴油发动机颗粒物数量排放测试研究

采用满足欧Ⅵ颗粒数量(PN)测试要求的AVL489颗粒计数器,对3台不同机型的柴油机进行了ESC,ETC和WHTC循环试验,并测量了PN排放情况。结果表明:在不同机型和不同试验循环下,PM(颗粒物质量)和PN排放的相关性较高;DOC+POC后处理可有效降低PN排放;热起动WHTC循环的PN排放比冷起动高,但差异很小;PN排放随转速的升高和负荷的加大而增高。     

基于柴油机排气热管理的喷油策略控制试验研究

为有效满足柴油机中低转速、中小负荷工况下颗粒捕集器(DPF)主动再生时的工作温度需求,利用发动机台架试验研究了中低负荷稳态工况下主喷正时、近后喷及次后喷参数等排气热管理主动控制措施对缸内燃烧过程、排气热状态及排放性能的影响规律。稳态试验结果表明:推迟主喷提前角缩短了滞燃期,燃烧持续期延长,缸内最高燃烧压力及峰值温度下降,瞬时放热率峰值减小且燃烧重心后移,同时燃油消耗率及烟度略有增加,DOC入口温度提升也不明显;引入近后喷使得缸内最高燃烧压力降低,但放热率第二峰值及后燃期有所增加,近后喷油量与主-近后喷间隔角的合理匹配能适当提高DOC入口温度,最高增幅可达19.3%,同时也能有效改善NOx排放和烟度;次后喷油量的增加能显著提升DPF入口温度,最大增幅达70%,但会导致燃油消耗率及HC逃逸量增加。依据样机全工况排温分布状态提出各区域升温喷油控制策略:低负荷区域采用"近后喷+次后喷"的喷油组合,并且采用较大喷油量;中大负荷区域逐渐减少近后喷,直至无近后喷,同时将主喷适当提前。     

EGR对轻型柴油机超细颗粒排放的影响

基于1台匹配废气再循环(EGR)系统的轻型柴油机,在中低负荷下研究了EGR对发动机超细颗粒排放的影响.研究发现:各工况下,随EGR率的增大,颗粒排放中核模态颗粒数量浓度在各粒径下有所减少,核模态颗粒排放数量速率和质量速率有减少趋势,且在最大扭矩转速的低负荷工况更加明显;积聚态颗粒数量浓度在各粒径下都增加,积聚态颗粒排放数量和质量速率也都增加,且中负荷时更加明显,而积聚态颗粒数量浓度峰值粒径基本没有改变.随EGR率的增大,总的超细颗粒排放数量速率在最大扭矩转速的低负荷工况减小,而其他工况都明显增加.由于积聚态颗粒总质量浓度占超细颗粒总质量浓度比例达99%,所以超细颗粒排放质量速率也都增加,几何平均粒径也都明显增大.在低负荷较低EGR率和中负荷较大EGR率时,过高的喷油压力都将使超细颗粒排放数量速率增加.     

燃油硫含量对国Ⅳ柴油轿车颗粒物排放特性的影响

对燃用硫含量分别为300mg/kg与43mg/kg的柴油和是否安装DPF对采用典型国Ⅳ排放控制技术的柴油轿车颗粒物排放特性的影响进行了试验研究.结果表明,未装DPF时,国Ⅳ柴油车燃用高含硫量燃油时的颗粒物质量排放较燃用低含硫量燃油时增加25.3%;安装DPF时增加22.2%.而颗粒物数量排放结果说明,燃油含硫量对安装DPF车辆的颗粒物数量浓度影响较大,燃用高含硫量燃油时的循环平均颗粒物数量浓度约为燃用低含硫量燃油时的4.8倍.研究同时表明,颗粒物排放主要在加速阶段产生,稳态工况和减速下颗粒物数量排放大幅降低.     

不同路线国Ⅳ车用重型柴油机非常规排放试验研究

采用AVL全流采样系统对3台国Ⅳ车用重型柴油机进行了ESC、ETC循环试验,研究了分别采用DOC+POC、DOC+DPF和SCR 3种不同技术路线时发动机NO2、SO2、NH3、HCHO和NOx的排放特性.结果表明,无论是ESC循环还是ETC循环,3种技术路线下的CO、HCHO、NH3排放依次恶化,NO2在NOx排放中的比例依次明显下降,但SCR路线在油耗和CO2排放方面具有相对优势.     

不同路线国Ⅴ车用重型柴油机微粒物中SOF和PAHs的对比研究

采用AVL全流采样(CVS)系统,对2台国Ⅴ车用重型柴油机进行了ESC和ETC循环试验,并利用气相色谱—质谱联用仪等设备对颗粒物中的可溶性有机物(SOF)和多环芳烃(PAHs)进行了分析。通过对比采用DOC+DPF和SCR两种技术路线柴油机的SOF和PAHs及其组分,对它们的排放特性进行了研究。研究发现,无论是ESC循环下还是ETC循环下,DOC+DPF路线发动机PM排放中SOF含量以及PAHs排放总浓度都要明显低于SCR路线发动机,PM中菲和芘的浓度会降低一半以上。     

Computational study on the effects of volume ratio of DOC/DPF and catalyst loading on the PM and NOx emission control for heavy-duty diesel engines

The use of a diesel particulate filter (DPF) in a diesel aftertreatment system has proven to be an effective and efficient method for removing particulate matter (PM) in order to meet more stringent emission regulations without hurting engine performance. One of the favorable PM regeneration technologies is the NO₂-assisted regeneration method due to the capability of continuous regeneration of PM under a much lower temperature than that of thermal regeneration. In the present study, the thermal behavior of the monolith during regeneration and the conversion efficiency of NO₂ from NO with an integrated exhaust system of a diesel oxidation catalyst (DOC) and DPF have been predicted by one-channel numerical simulation. The simulation results of the DOC, DPF, and integrated DOC-DPF models are compared with experimental data to verify the accuracy of the present model for the integrated DOC and DPF modeling. The effects of catalyst loading inside the DOC and the volume ratio between the DOC and DPF on the pressure drop, the conversion efficiency, and the oxidation rate of PM, have been numerically investigated. The results indicate that the case of the volume ratio of ‘DOC/DPF=1.5’ within the same diameter of both monoliths produced close to the maximum conversion efficiency and oxidation rate of PM. Under the engine operating condition of 175 kW at 2200 rpm, 100% load with a displacement of 8.1, approximately 55 g/ft³ of catalyst (Pt) loading inside the DOC with the active Pt surface of 5.3 m²/g_pt was enough to maximize the conversion efficiency and oxidation rate of PM.     

DOC辅助DPF再生的二次污染研究

在氧化型催化转换器(DOC)前端的排气管中喷入柴油,通过提高柴油机尾气温度、燃烧并去除柴油机微粒捕集器(DPF)中的PM,实现了DPF再生。对整个再生过程中尾气成分进行分析和计算,发现碳氢化合物(HC)为主要二次污染物,且排放相对较大。通过试验方法,分别研究喷油流量和喷油时DOC前端排气温度对再生过程中HC排放的影响,并依此提出保温处理、分阶段喷油和低速再生等三项优化措施。优化后再生过程中HC排放降低了68%,且燃油经济性提高了21%。     

Effects of Residual Ash on Dpf Capture and Regeneration

To study the effects of residual ash on the capture and regeneration of a diesel particulate filter (DPF), repeated capture and complete regeneration experiments were conducted. An engine exhaust particulate sizer was used to measure the particle size distribution of diesel in the front and back of DPF. Discrepancies in the size distribution of the particulate matter in repeated trapping tests were analyzed. To achieve complete DPF regeneration, a DPF regeneration system using nonthermal plasma technology was established. The regeneration carbon removal mass and peak temperatures of DPF internal measuring points were monitored to evaluate the effect of regeneration. The mechanism explaining the influence of residual ash on DPF capture and regeneration was thoroughly investigated. Results indicate that the DPF trapping efficiencies of the nuclear-mode particles and ultrafine particles have significant improvements with the increase quantity of residual ash, from 90 % and 96.01 % to 94.17 % and 97.27 %, respectively. The exhaust backpressure of the DPF rises from 9.41 kPa to 11.24 kPa. Heat transfer in the DPF is improved with ash, and the peak temperatures of the measuring points accordingly increase. By comparing the regeneration trials, the elapsed time for complete regeneration and time difference for reaching the peak temperature between adjacent reaction interfaces are extended with increased quantity of ash. The carbon removal mass rises by 34.00 %.     

加载减速工况下带有DPF柴油车的颗粒物排放

基于加载减速工况,利用ELPI能够有效研究颗粒物排放状况以及其数目浓度和质量浓度在粒径上的分布,研究证实,这种测试技术具有很高的DPF性能鉴别能力。通过量化分析颗粒物在DPF前后粒径上的浓度分布以及图解DPF前后的浓度差值,可以非常清晰地发现该DPF对于不同粒径的过滤性能,为开发和匹配柴油车颗粒物过滤器提供一种有效的手段。     

满足国Ⅴ排放的重型柴油机排气后处理技术

研究了国外重型发动机在欧Ⅳ到欧Ⅴ阶段(或US2007到US2010)的技术路线,并探讨国内重型柴油机达到国Ⅴ排放可采用的排气后处理技术方案。由于柴油机排放物PM与NOx存在折中效应,为达到国Ⅴ排放标准,应采用组合式后处理技术。在各种后处理技术方案中,SCR+DOC+DPF/POC和EGR+DOC+DPF是两种主要的技术措施,而LNT+DOC+DPF技术对排气中的S特别敏感。     

Nano-particle emission characteristics of European and Worldwide Harmonized test cycles for heavy-duty diesel engines

This study was conducted for the experimental comparison of particulate emission characteristics between the European and World-Harmonized test cycles for a heavy-duty diesel engine as part of the UN/ECE PMP ILCE of the Korea Particulate Measurement Program. To verify the particulate mass and particle number concentrations from various operating modes, ETC/ESC and WHTC/WHSC, were evaluated. Both will be enacted in Euro VI emission legislation. The real-time particle emissions from a Mercedes OM501 heavy-duty golden engine with a catalyst based uncoated golden DPF were measured with CPC and DMS during daily test protocol. Real-time particle formation of the transient cycles ETC and WHTC were strongly correlated with engine operating conditions and after-treatment device temperature. The higher particle number concentration during the ESC #7 to #10 mode was ascribed to passive DPF regeneration and the thermal release of low volatile particles at high exhaust temperature conditions. The detailed average particle number concentration equipped for golden DPF reached approximately 4.783E+11 #/kWh (weighted WHTC), 6.087E+10 #/kWh (WHSC), 4.596E+10 #/kWh (ETC), and 3.389E+12 #/kWh (ESC). Particle masses ranged from 0.0011 g/kWh (WHSC) to 0.0031 g/kWh (ESC). The particle number concentration and mass reduction of DPF reached about 99%, except for an ESC with a reduction of 95%.     

Carbon Deposit Incineration During Engine Flameout Using Non-Thermal Plasma Injection

In order to investigate the influence of initial regeneration temperatures on diesel particulate filter (DPF) regeneration, an experimental study of DPF regeneration was implemented using a dielectric barrier discharge (DBD) reactor, aided by exhaust waste heat after engine flameout. DPF trapping characteristics and carbon deposit mass were discussed to facilitate further data analysis and calculation. DPF regeneration was then investigated by comparison analysis of deposit removal mass, backpressure drop, and internal temperature change. The results revealed that a large amount of particulate matter (PM) was deposited in DPF with a high filtration efficiency of about 90 %. The deposit removal rate and percentage drop of the backpressure both maximized at the initial temperature of 100 °C. During DPF regeneration, the sharp rise of internal temperature indicated vigorous PM incineration and high CO₂ emission. The results successfully demonstrated DPF regeneration using non-thermal plasma injection during engine flameout, and prominent heat durability was achieved in this method.     

一种基于神经网络的氧化催化器出口温度控制方法

氧化催化器(DOC)出口温度控制是实现颗粒捕集器(DPF)主动再生控制的关键。本文介绍一种基于神经网络的氧化催化器出口温度控制方法,首先结合DOC系统的实际特征以及DOC传热及化学反应特性建立了一阶延迟DOC出口温度模型,然后在温度模型基础上基于神经网络建立了DOC出口温度预测模型,最后将DOC出口温度预测值作为闭环反馈输入建立反馈控制器计算HC喷射量进而控制DOC出口温度。本方法采用整车试验中连续变化工况来验证,试验结果表明DOC出口温度在DPF再生过程中控制在600±20℃范围内,满足DPF精确再生控制要求。     

DPF对柴油车颗粒物排放的影响研究

利用ELPI（电子低压冲击器）对加载DPF的柴油车分别在DPF前后和未安装DPF时进行取样,能有效研究颗粒物排放状况以及颗粒物数量浓度和质量浓度在粒径上的分布。研究发现,安装DPF后将增加车辆发动机排放的颗粒物数量和质量,但经过DPF过滤后,颗粒物质量和数量都会大幅减少,过滤效果良好。     

Comparison of fuel efficiency and exhaust emissions between the aged and new DPF systems of Euro 5 diesel passenger car

This study was conducted to examine the impact of aged and new DPF systems of the Euro 5 diesel passenger car on fuel efficiency and exhaust emissions. Test diesel vehicle used in this study was equipped with diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) as aftertreatment systems, and satisfied the Euro-5 emissions standard. The displacement volume of engine was 1.6 L and the cumulative mileage was 167,068 km before the test. The FTP-75 test procedure was used, and the time resolved and weight based exhaust emissions of total hydrocarbon (THC), carbon monoxide (CO) and nitrogen oxides (NOx) were measured. The results show that the vehicle with the new DPF system has lower emissions of THC, CO and NOx than the aged one, and fuel efficiency also increased about 5 percent. The aged DPF system had higher backpressure due to the particulate matter (mostly in the form of ash) accumulated in the DPF. As was shown in the analysis using X-CT (X-ray computer tomography), the aged DPF system had particulate matter (PM) accumulated to a length of 46.6 mm. In addition, a component analysis of PM through XRF (X-ray fluorescence) analysis found that 50 % or more of the components consisted of the P, S, Ca, and Zn.