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周小波,胡清华,闫峰,苏万华.重型柴油机颗粒物分布规律的试验研究[J].农业工程学报,2018,34(13):62-69.DOI:10.11975/j.issn.1002-6819.2018.13.008
重型柴油机颗粒物分布规律的试验研究
投稿时间:2018-03-26  修订日期:2018-06-06
中文关键词:  柴油机  排气  颗粒  稳态工况  瞬态工况  分布规律  核态和积聚态颗粒
基金项目:国家高技术研究发展计划(863计划)"基于柴油机均质压燃发动机关键技术攻关及样机研制"(2012AA111714),国家自然科学基金重点项目"直喷式内燃机燃烧过程和功转化率最大化的研究"(51236005)
作者单位
周小波 1. 天津大学计算机科学与技术学院天津 300350
2. 天津大学内燃机燃烧学国家重点实验室天津 300072
 
胡清华 1. 天津大学计算机科学与技术学院天津 300350
 
闫峰 3. 中国汽车技术研究中心有限公司天津 300300
 
苏万华 2. 天津大学内燃机燃烧学国家重点实验室天津 300072
 
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中文摘要:为了同时控制车用重型柴油机的颗粒物排放质量和数目,该文对稳态工况及瞬态工况下柴油机排放颗粒物分布规律进行了试验研究。试验结果表明:在稳态工况下,随着负荷的增加或者转速的提高,积聚态及核态颗粒物数目浓度、中位直径(count median diameter,CMD)、表面积和质量均呈现增大趋势,且峰值向大粒径方向偏移。在本研究中,稳态工况全工况总颗粒物数目浓度为1.5×106~4.5×106个/cm3,积聚态颗粒物数目浓度为2×106~1×107个/cm3,而核态颗粒物数目浓度为1×107~3×107个/cm3,在总颗粒物数目浓度中占比为65%~96%。全工况当量比均小于0.7,在中低转速,当量比对颗粒物分布影响较为明显,在高转速尤其是大负荷条件下,当量比的影响减弱。在瞬态工况下,颗粒物数目浓度出现了与颗粒物质量类似的排放尖峰现象,浓度峰值达到2×108~7×108个/cm3,比其对应的稳态工况出现的浓度峰值高出1个数量级。而且排放尖峰现象中,积聚态颗粒物数目浓度占主要部分,其峰值浓度比稳态工况要高出2个数量级,此时排放尖峰现象中核态颗粒物数目浓度也出现明显增长。排放尖峰现象对应的粒径主要集中在积聚态颗粒物的50~200 nm范围和核态颗粒物的6~8 nm及20~50 nm范围。这主要是因为当量比在瞬态过程出现了超过临界当量比0.8的情况。研究结果对重型柴油机颗粒物排放控制以及生成机理有重要指导意义,并可为排放后处理器的匹配计算提供数据支持。
Zhou Xiaobo,Hu Qinghua,Yan Feng,Su Wanhua.Experimental study on particle distribution of exhaust emission of heavy-duty diesel engine[J].Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE),2018,34(13):62-69.DOI:10.11975/j.issn.1002-6819.2018.13.008
Experimental study on particle distribution of exhaust emission of heavy-duty diesel engine
Author NameAffiliation
Zhou Xiaobo 1. School of Computer Science and Technology, Tianjin University, Tianjin 300350, China
2. State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
 
Hu Qinghua 1. School of Computer Science and Technology, Tianjin University, Tianjin 300350, China
 
Yan Feng 3. China Automotive Technology & Research Center Co., Ltd,, Tianjin 300300, China
 
Su Wanhua 2. State Key Laboratory of Engines, Tianjin University, Tianjin 300072, China
 
Key words:diesel engineers  exhaust gas  particulate matter  steady state condition  transient condition  distribution function  nucleation and accumulation mode
Abstract:In recent years, smog has emerged in most of major cities in China. Epidemiological and toxicological studies showed that the ultrafine particles in the atmosphere adhere to a large number of toxic substances, which can cause serious harm to human respiratory and cardiovascular and other organs after they enter the human body through the respiratory tract. and the data indicated that it had a significant correlation with human morbidity and mortality. Particulate emissions from diesel engines are an important source of ultrafine particles in urban atmosphere. The researchers found that the weighing method of particulate matter detection cannot accurately reflect the emission levels of internal combustion engines. This new method for measuring the number of particulate matter emissions after removing volatile matter from the method has been widely recognized and included in the scope of regulatory investigation. However, there are few studies on the number and size distribution of particles in the transient process of diesel engine. In order to simultaneously control the quality and quantity of particulate matter emitted from heavy duty diesel engines, the particle distribution of exhaust particulates from diesel engines under steady and transient conditions was studied. The test bench is a 12 L heavy duty diesel engine and an electric dynamometer. The test bench is a prototype with no post-processor and meets the Euro IV regulations. It has been certified by China Automotive Technology Research Center (CATRC). The engine intake system consists of a two-stage turbocharging system with variable geometry section turbine (VGT), a high-pressure EGR system and an intake valve late closing system (IVCT system, which is developed by the research group independently). Cambustion DMS500 fast particle spectrometer was used to analyze the particle size distribution of diesel engine under transient conditions. The experimental results showed that, in the steady state, with the increase of load or speed, the concentration of accumulated particles showed an upward trend, corresponding to the increase of count median diameter (CMD), the surface area and mass of accumulated particles showed an increasing trend, and the peak value shifted to the direction of large particle size. In this study, the total number concentration of particles during the steady state is 1.5×106-4.5×106/cm3, and accumulation mode particle was 2×106-1×107/cm3, nucleation mode particle was 1×107-3×107/cm3 which account for 65%-96%. In the steady state, the number of nucleation mode particles is the main source of the total number of particles. The equivalent ratio of all steady state conditions is less than 0.7. The effect of equivalent ratio on particle distribution is obvious at middle and low rotational speed, but weakens at high rotational speed, especially at high load. The European Transient Cycle (ETC) was used for the transient test. In transient condition, the spikes also appear in the number concentration of particles which similar to that of quality of particulate matter, and the number concentration peak even reaches 2×108-7×108 /cm3, which is 2 orders of magnitude higher than that of the corresponding steady state operation. The number concentration of nucleation mode particle increases significantly in the spikes, but the proportion of the number concentration of nucleation mode particle in the total particles is reduced. The number concentration of accumulation mode particle is the main part of the spikes which is different from the steady state condition. The particle size peak is mainly concentrated in the 50-200 nm range at accumulation mode, the 6-8 nm and 20-50 nm at nucleation mode, this mainly because that the equivalent ratio in the transient process appears to exceed the critical equivalent ratio of 0.8 working conditions. The equivalent ratio does not exceed 0.7 in steady state operation, but the condition corresponding to the emission peak appears to exceed the critical equivalent ratio 0.8. The results are of great significance for particulate emission control and generation mechanism of heavy-duty diesel engine, and can provide data support for matching calculation of post-exhaust processor.
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