摘要
在一台单缸柴油机上试验研究了预混合率对正庚烷/柴油复合HCCI(Homogeneous Charge Compression Ignition)燃烧的影响。结果表明:复合HCCI燃烧呈现三阶段放热模式,并且随着预混合率的增大,复合HCCI燃烧第二阶段高温反应着火提前,燃烧持续期缩短,第三阶段扩散燃烧滞燃期缩短,同时缸内最高压力和温度均升高。复合HCCI的NOx排放与纯柴油直喷相比有显著降低,且随预混合率的增大先降低后升高;碳烟排放在预混合率较小时与原机基本持平。同时复合HCCI的CO排放随预混合率增大先增后减,而HC则与预混合率成一定的正比关系。此外,复合HCCI燃烧能够明显改善原机中低负荷下的热效率。
This paper investigated the effect of premixed ratio on the compound HCCI combustion. The experiments were carried out on a single cylinder diesel engine fueled with n-heptane and diesel dual fuel. The test results indicated that the compound HCCI combustion showed a three-stage heat release pattern. Increasing the premixed ratio leaded to the advancement of the start of second phase high temperature HCCI combustion and decreasing of the correspondent duration. Meanwhile, the ignition delay of third phase diffusive combustion was shortened and the peak cylinder pressure and temperature were increased. Compared with the conventional diesel engine, NOx emission of the compound HCCI was reduced dramatically and it gave the behavior from decreasing to increasing with the increase of the premixed ratio. The smoke emission remained the same level in comparison with the prototype diesel engine when the premixed ratio is relatively low. The study also revealed that HC increased monotonically with the increase of premixed ratio while CO emission exhibited a rising tendency at small premixed ratio but a descending trend at large premixed ratio. The compound HCCI could effectively improve the thermal efficiency of the original diesel engine at low-to-medium load ranges.
出处
《内燃机学报》
EI
CAS
CSCD
北大核心
2008年第2期128-133,共6页
Transactions of Csice
基金
国家重点基础研究发展计划资助项目(2007CB210007)
教育部博士点基金资助项目(20070248112)
