Combustion Stabilities and Cycle-by-Cycle Variations of n-Heptane Homogeneous Charge Compression Ignition Combustion

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• 作者：Xingcai L&uuml ; Libin Ji ; Junjun Ma ; Zhen Huang
• 刊名：Energy & Fuels
• 出版年：2007
• 出版时间：May 2007
• 年：2007
• 卷：21
• 期：3
• 页码：1468 - 1473
• 全文大小：566K
• 年卷期：v.21,no.3(May 2007)
• ISSN：1520-5029

文摘

In this paper, the combustion stabilities and cycle-by-cycle variations of n-heptane homogeneous chargecompression ignition (HCCI) combustion were investigated. In-cylinder pressures of 100 combustion cyclesunder typical operation conditions including partial burn (8.33 mg/cycle), normal combustion (12.6 mg/cycle),and knock combustion (16.7 mg/cycle) were recorded. Consequently, cycle-by-cycle variations of combustionparameters and performance parameters were analyzed. Furthermore, the interdependency between thecombustion parameters and/or performance parameters was evaluated. The results reveals that, during thelow-temperature reaction (LTR) region, the coefficient of variations (COV) of the ignition timing, initialtemperature, and crank angle corresponding to the peak value of the heat release rate (HRR) are less than 3%.The cycle-by-cycle variations of the second stage combustion are strongly affected by the fuel equivalenceratio, and COVs improved substantially with the increase of the fuel concentrations. Meanwhile, both of thepeak values of the HRR during the LTR and high-temperature reaction (HTR) show obviously cycle-to-cyclevariations, and COVs increase with the fuel supply rate. Regarding the cycle-by-cycle variations of theperformance parameters, COVs of the maximum in-cylinder pressure and pressure rise rate are very smallexcept for the knock combustion. On the contrary, cycle-to-cycle variations of indicated mean effective pressure(IMEP) and indicated thermal efficiency are very small except for the partial combustion, and variations improvewith the increase of the fuel supply rate.