DPF喷油助燃装置工作参数对再生过程的影响.doc
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1、DPF喷油助燃装置工作参数对再生过程的影响Study of the Impact of the Working Parameters of a Burner-type DPF on Regeneration FU Jun1,2,GONG Jin-ke1?k ,WU Gang1,LONG Gang1,YU Ming-guo1,LIU Xiang-ling1 (1.State Key Laboratory of Advanced Design and Manufacture for Vehicle Body, Hunan Univ, Changsha, Hunan 410082, China; 2
2、.Dept of Mechanical and Energy Engineering, Shaoyang Univ, Shaoyang, Hunan 422004,China) Abstract: Taking a burner-type diesel particulate filter (DPF) as an example and based on the pyrogenation regeneration model, the variety laws of the exhaust back-pressure, particulate layer thickness and wall
3、maximum temperature, etc. during the burner-type DPF regeneration were studied and analyzed under different working parameters, such as oil-spray pressure, spray rate and air-supply flux. The results indicate that the working parameters could influence the regeneration evidently. With the improvemen
4、t of the oil-spray pressure, the wall maximum temperature increased markedly, and the regeneration rate was quickened. The burner power became stronger with the increase of oil -spray rate, and the amplitude of the wall maximum temperature was greater. But for the safe endurable temperature of DPF,
5、the oil-spray rate must be controlled. When the oil-spray rate reached a certain extent, the oxygen content in the exhaust was deficient, the combustion efficiency decreased, and the soot oxidation velocity and regeneration rate slowed down. It increased the oxygen content by air supply and the rege
6、neration process quickened. But with more air-supply quantity, the regeneration may slow down because of the enhancement of convection transfer heat loss. Key words: diesel engine; burner-type DPF; working parameter; regeneration ? 柴油机具有热效率高、适应性好、功率范围宽等优点,在车辆、施工机械等方面应用极为广泛,其排放的微粒粒径小、重量轻,能长时间悬浮于大气中,极
7、大地危害着人类的健康,随环保形势的日益严峻,柴油机的微粒排放问题已引起了人们足够的重视,对其有效控制已成为当前柴油机发展过程中极其重要且极具挑战的课题.目前,采用微粒捕集器(DPF)被认为是解决柴油机微粒排放问题最有效的手段1-2,其再生问题也成了人们研究的热点,在诸多再生方式中,喷油助燃再生技术不受油品质量限制,燃烧器采用与柴油机相同的燃料,且各部件成熟件多,装车使用时不需对发动机原结构做太大的改动,是一种适用性好、效率高和可靠性好的再生技术3-4.因此,本文以喷油助燃再生方式为例,结合DPF再生过程理论,基于自行设计的喷油助燃装置,通过改变工作参数,如喷油压力、喷油率、补气量等来研究其对D
8、PF再生过程排气背压、微粒层厚度及壁面峰值温度等的变化规律,为喷油助燃再生装置工作过程参数的控制与优化提供理论指导. 1 喷油助燃再生工作原理 图1为DPF喷油助燃再生工作示意图.在DPF捕集微粒过程中,由分布在过滤体前后的压力传感器1,2测得的排气背压信号实时反馈至电控单元(ECU),且与储存在ECU的排气背压阈值MAP图进行比较,当压力降超过MAP图在该工况下的设定值时,燃烧器立即工作,喷油系统、供气系统分别通过喷油器3、进气阀4按ECU所发出的指令定时定量进行喷油和进气,迅速地完成雾化和混合过程.混合气形成后则由安装在燃烧器出口处的电热塞5引燃,形成高温燃气,使排气温度大幅提高,当柴油机
9、排气温度(由传感器6,7测定)达到微粒的着火点,且排气中氧气含量充分时(ECU可根据发动机负荷氧浓度关系控制进气阀4的开启来保证再生过程的氧含量),则沉积在DPF中的微粒迅速氧化燃烧,实现DPF的再生. 就再生过程而言,对于既定的喷油助燃装置,其喷油压力、喷油率及补气量等的变化对排气温度、废气中氧含量及孔道微粒沉积厚度等有重要影响,进而影响过滤体的再生过程.为此,本文将通过调整喷油压力、喷油率及补气量等参数,实时测取相关试验数据,建立过滤体不同的再生条件,基于过滤体孔道再生数学模型研究其再生特性. 2 再生过程数学模型 根据Bissett的研究5,结合过滤体结构及微粒燃烧特点,对以往再生模型做
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- 关 键 词:
- DPF 助燃 装置 工作 参数 再生 过程 影响
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