喷油策略耦合EGR对柴油机燃烧过程与CDPF再生性能的影响

陈贵升; 王凯; 杨杰; 张韦; 徐劲松; 雒婧

陈贵升, 王凯, 杨杰, 张韦, 徐劲松, 雒婧.喷油策略耦合EGR对柴油机燃烧过程与CDPF再生性能的影响[J].内燃机工程,2017,38(3):131-141.

喷油策略耦合EGR对柴油机燃烧过程与CDPF再生性能的影响

Effects of Fuel Injection Strategy with EGR on Diesel Engine Combustion Process and CDPF Regeneration Performance

DOI：

Key Words:high pressure common rail diesel engine injection strategy exhaust gas recirculation catalytic particulate filter regeneration performance

基金项目:国家自然科学基金项目（51665023, 61263026）；云南省教育厅科学研究基金项目（2016YJS027）；河北省自然科学基金项目（E2015202321）

作者	单位
陈贵升, 王凯, 杨杰, 张韦, 徐劲松, 雒婧	1.昆明理工大学云南省内燃机重点实验室, 昆明 650500； 2.河北工业大学能源与环境工程学院, 天津 300401

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摘要:以匹配了可变截面几何增压系统（VGT）的D19高压共轨柴油机为研究机型, 采用GT-Power和AVL FIRE构建了一维热力学整机模型和催化型微粒捕集器（CDPF）三维仿真模型, 针对3 000 r/min、50%负荷工况, 研究了喷油策略耦合废气再循环（EGR）对燃烧过程和CDPF再生性能的影响。研究表明：随主喷定时提前, 有效燃油消耗率（BSFC）先降后升, 排气温度降低, 排气流量与氧浓度变化则较小, 排气中一氧化氮（NO）增加, CDPF再生速率逐渐降低, 颗粒物残余量、压降与CDPF出口端二氧化氮（NO2）同时增加；随EGR率增大, BSFC和排气温度升高, 排气流量、排气氧浓度、排气中NO浓度则同时降低。在主喷定时较晚时, 随EGR率增大, CDPF再生速率先升后降, 颗粒物残余量先降低后略升高；而在主喷定时较早时, 随EGR率的增大, CDPF再生速率降低, 颗粒物残余量增多。在主喷定时较晚时, 提高喷油压力使BSFC和排气温度明显降低；而在主喷定时较早时, 提高喷油压力导致BSFC反而快速增加。此外, 随喷油压力提高, 排气流量与氧浓度变化较小, 排气中NO浓度增加, CDPF再生速率逐渐减小, 颗粒物残余量、压降和CDPF出口端NO2排放同时升高。总体上, 相比喷油压力, 主喷定时对CDPF再生过程影响更大。

Abstract:Based on a D19 high pressure common-rail diesel engine with VGT (variable geometry turbocharger), an one-dimensional thermodynamic engine model and a three-dimensional CDPF (catalytic diesel particulate filter) model were built by using the GT-Power and AVL Fire. At 3 000 r/min with 50% load, the effects of fuel injection strategy with EGR (exhaust gas recirculation) on engine combustion process and CDPF regeneration performance were studied. The results show that, with the advance of the main-injection timing, the BSFC (brake specific fuel consumption) decreases first and then increases, and the exhaust temperature reduces, while the changes of the exhaust flow and oxygen concentration are not obvious. In addition, the NO in exhaust increases, the CDPF regeneration rate decreases gradually, and the residual particulate matter, pressure drop, as well as NO2 at the CDPF outlet increase simultaneously. With the increase of the EGR rate, the BSFC and exhaust temperature increase, while the exhaust flow, oxygen concentration and NO in exhaust all reduce simultaneously. With delayed main-injection timing, the CDPF regeneration rate increases first and then decreases as the EGR rate increases, while the residual particulate matter decreases first then increases slightly. With earlier main-injection timing, the CDPF regeneration rate reduces while the residual particulate matter increases as the EGR rate increases. With later main-injection timing, increasing the injection pressure can decrease the BSFC and exhaust temperature obviously, while with earlier main-injection timing, improving the injection pressure can increase the BSFC greatly. In addition, with the increase of the injection pressure, the changes of the exhaust flow and oxygen concentration are slight, the NO in exhaust increases, the CDPF regeneration rate decreases slowly, and the residual particulate matter, pressure drop as well as NO2 emission at the CDPF outlet increase simultaneously. In short, compared with the injection pressure, the influence of the main-injection timing on the CDPF regeneration process is greater.

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