热分层对HCCI燃烧过程的影响

Combustion Process of Homogeneous Charge Compression Ignition Under Different Thermal Stratification

在一台经改装的单缸光学发动机上进行不同热分层下均质压燃燃烧过程实验研究.保证每循环供油量一定,燃料为正庚烷,转速为600.r/min,进气压力为0.1.MPa,进气温度分别为95.℃和125.℃;循环冷却水温度分别为55.℃、65.℃和85.℃.研究结果表明,冷却水温度和进气温度的变化,改变了缸内温度分布,对HCCI这种受控于化学反应动力学的燃烧过程有很大影响,引起微弱自燃着火、局部燃烧淬熄和相对均匀燃烧等不同燃烧过程;缸内热分层越大,自燃着火传播速度越慢,燃烧的不均匀性越大;增大缸内热分层,可以降低燃烧反应速率,具有拓宽HCCI运转工况范围的潜力.

To study the combustion processes of homogeneous charge compression ignition（HCCI）under different thermal stratification, the tests were carried out on a modified single-cylinder optical engine. The fuel quantity per cycle（Qcyc）Was fixed at 17.3 mg. The intake pressure and speed were fixed at 0.1 MPa and 600 r/min, respectively. In order to explore natu- ral thermal stratification by different heat-transfer rates, coolant/water temperature and intake temperature（Tin）were varied. The coolant temperature was set to be 55 ℃, 65 ℃ and 85 ℃, and the intake temperature was set to be 95 ℃ and 125 ℃. The results show that, with the change of coolant water and inlet temperature, in-cylinder temperature distribution will be changed, leading to different combustion processes, such as faint auto-ignition, partial combustion quench and com- parative homogeneous combustion, which indicates that in-cylinder temperature distribution has strong effect on HCCI combustion processes. With the increase of thermal stratification, combustion rate decreases, while combustion heteroge- neity increases, which will extend the operating range of HCCI.