摘要
利用CO-Ф-T图开展了混合速率对柴油机低温燃烧影响的模拟研究。首先，通过正庚烷详细化学反应动力学单区模型计算，建立了CO-Ф-T图，发现柴油机低温燃烧进程在当量比小于1和温度在1400～2100K内结束时，能够获得高效清洁燃烧。然后，利用带有质量交换且考虑传热损失的化学反应动力学两区模型，结合CO-Ф-T图，研究不同EGR率下不同混合速率对柴油低温燃烧的影响，发现在低温燃烧的后期，即混合控制燃烧阶段，混合速率应当随EGR率增加而增加。但是，当混合速率过高时，燃烧路径容易进入NOx生成区；而混合速率过低时，燃烧进程容易“淬熄”在高CO生成区。因此低温燃烧要同时获得较高的效率和较低的NOx排放，混合速率应当随EGR率增加而适当增加。
The effects of mixing on low temperature diesel combustion were studied based on a new quantitative ＂ Ф（ equivalence ratio）-T（temperature） ＂ map for CO formation. Firstly, the CO-Ф-T map was created by performing the zero dimensional calculations using a detailed chemistry of n-heptane. Based on the CO-Ф-T map, it is found that the low emission and high efficiency are obtained simultaneously as the low temperature diesel combustion is completed within the region where COmbustion temperature is approximately from 1 400 K to 2 100 K, and at the lean side of stoichiometric equivalence ratio. Secondly, a twozone chemical kinetic model considering both heat loss and mass transfer between the zones was developed to explore the low temperature combustion process at different EGR levels as well as mixing rates on the CO-Ф-T map. The results show that, on mixing-controlled burning phase, when the mixing rate is too high or too low, the combustion paths tend to enter the zones of higher NOx formation or higher CO formation, respectively. Therefore, as EGR rate increases, mixing rate must properly increase to achieve high efficiency and low NOx emissions simultaneously.
出处
《内燃机学报》
EI
CAS
CSCD
北大核心
2009年第2期97-102,共6页
Transactions of Csice
基金
国家重点基础研究发展规划项目(2007CB210001)
国家自然科学基金重点项目(50636040)
内燃机燃烧学国家重点实验室开放研究项目(SKLE200801)
作者简介
黄豪中，博士后，E—mail：hhz421@tom．com。
