Dual-fuel RCCI engine combustion modeling with detailed chemistry considering flame propagation in partially premixed combustion
Dual-fuel RCCI engine combustion modeling with detailed chemistry considering flame propagation in partially premixed combustion
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DOI：
10.1016/j.apenergy.2017.06.021
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发表时间：
2017-10
期刊：
影响因子：
11.2
通讯作者：
Dezhi Zhou;Wenming Yang;Feiyang Zhao;Jing Li
中科院分区：
文献类型：
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作者：
Dezhi Zhou;Wenming Yang;Feiyang Zhao;Jing Li
在均匀充量压燃（HCCI）发动机和分离充量（CDC）发动机这两个极限条件下，CHEMKIN耦合计算流体动力学（CFD）方法在预测化学控制燃烧和混合控制燃烧方面都有很好的效果。在这项研究中，它表明，在某些情况下，在新的燃烧模式反应性控制的压缩点火（RCCI）发动机的火焰传播存在，CHEMKIN方法可能无法预测的燃烧特性。为了扩展现有的CHEMKIN模型在燃烧中的能力，提出了一个火焰传播模型（FPM）占部分预混混合物中的燃烧，并耦合到CFD框架KIVA 4。在该模型中，湍流火焰速度的计算，并在湍流火焰刷的热释放和物种转化率求解详细的化学动力学。NOx子机制和九步唯象碳烟模型也耦合到当前的集成模型的排放预测。在3台双燃料试验机上进行了缸内压力、放热率、NOx和碳烟排放的对比试验，验证了模型的有效性。CHEMKIN和CHEMKIN-FPM也进行了比较，在他们的预测能力，在不同的燃烧制度。结果表明，在CHEMKIN不能预测燃烧特性的特定工况下，CHEMKIN-FPM具有较好的预测燃烧特性的上级能力。
In the two limits of a well-mixed charge (e.g. homogenous charge compression ignition (HCCI)) engine, and a well separated charge (e.g. conventional diesel combustion (CDC)) engine, the CHEMKIN coupled computational fluid dynamics (CFD) codes approach has been proved to work well in predicting both chemistry controlled combustion and mixing controlled combustion. In this study, it is shown that for some certain cases in the new combustion mode reactivity controlled compression ignition (RCCI) engine where flame propagation exists, the CHEMKIN approach could fail to predict the combustion characteristics. To extend the capability of the existing CHEMKIN models in combustion, a flame propagation model (FPM) accounting for combustion in partially premixed mixtures was proposed and coupled into the CFD framework KIVA4. In this FPM model, the turbulent flame speed was calculated and the heat release and species conversion rate in the turbulent flame brush was solved with detailed chemical kinetics. A NOx sub-mechanism and a nine-step phenomenological soot model were also coupled into the current integrated model for emission prediction. This model was validated in 3 different dual-fuel experimental engines by comparing the in-cylinder pressure, heat release rate (HRR), NOx emissions and soot emissions. The CHEMKIN and CHEMKIN-FPM were also compared in terms of their capability of predicting the combustion in different combustion regimes. The results show that under certain operating conditions when CHEMKIN failed in the combustion prediction, the current CHEMKIN-FPM shows a superior ability in predicting combustion characteristics.