A dual-scale flamelet/progress variable (DS-FPV) approach is developed to predict polycyclic aromatic hydrocarbon (PAH) formation in the environment of coal combustion. An additional progress variable C_PAHs is newly defined in this approach to describe the evolution of PAHs, and the major species and temperature are still described by the traditional progress variable defined in the original FPV approach. Detailed chemistry simulations of a counterflow flame fueled with volatile matter and char off-gas are performed, and the solutions are regarded as references to evaluate the developed DS-FPV approach. It is found that the position of PAHs formation is located at the region that is close to the flame center in the fuel-rich side, and PAHs are mainly produced at the stage of volatile combustion. The original FPV approach can correctly predict the major species and temperature, but significant discrepancies appear for the species of PAHs that has a very weak correlation with the traditional progress variable. This issue is successfully addressed by the DS-FPV approach. Both the a priori and a posteriori analyses demonstrate that the developed DS-FPV approach can accurately and efficiently predict not only the distribution of major species and temperature but also the distribution of PAHs, although the peak values of mass fractions of PAHs are slightly underpredicted. The extension of this approach to turbulent pulverized coal combustion needs further efforts in the future.

中文翻译：

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煤燃烧条件下双尺度小波/进程变量法预测多环芳烃形成

开发了一种双尺度火焰/进度变量（DS-FPV）方法来预测煤燃烧环境下多环芳烃（PAH）的形成。额外的进度变量C _PAH用这种方法新定义了PAHs，以描述PAHs的演变，主要物种和温度仍由原始FPV方法中定义的传统进度变量描述。进行了以挥发性物质和焦炭尾气为燃料的逆流火焰的详细化学模拟，并将该解决方案视为评估已开发的DS-FPV方法的参考。发现PAHs的形成位置位于燃料富集侧中靠近火焰中心的区域，并且PAHs主要在挥发性燃烧阶段产生。最初的FPV方法可以正确预测主要物种和温度，但是与传统进程变量相关性非常弱的PAH物种却出现了明显差异。DS-FPV方法成功解决了此问题。这俩先验和后验分析表明，尽管PAHs质量分数的峰值略有预测，但发达的DS-FPV方法不仅可以准确有效地预测主要物种和温度的分布，而且可以准确预测PAHs的分布。这种方法扩展到湍流煤粉燃烧需要在未来进一步的努力。