An extended flamelet/progress variable model for coal/biomass co-firing flame
An extended flamelet/progress variable model for coal/biomass co-firing flame
复制标题
DOI：
10.1016/j.proci.2022.07.063
复制
发表时间：
2022-09
影响因子：
3.4
通讯作者：
Jiangkuan Xing;K. Luo;R. Kurose;Jianren Fan
中科院分区：
文献类型：
--
作者：
Jiangkuan Xing;K. Luo;R. Kurose;Jianren Fan
煤/生物质混烧（CBCF）被认为是减少化石燃料使用排放的可持续替代方案之一。它具有由煤和生物质颗粒的异步反应行为引起的复杂的反应阶段和燃料流，不能用传统的二混合分数（2Z）煤火焰/进度变量（FPV）模型很好地表示。为了解决这个问题，我们在本研究中开发了 CBCF 火焰的扩展 FPV 模型。首先，进行三维（3D）点粒子直接数值模拟（PP-DNS）来探索混烧火焰的燃烧特性，为模型开发提供参考。其次，通过引入额外参数来区分挥发物来源，开发了扩展的 FPV 模型，并通过先验研究以及与传统煤炭/生物 2Z-FPV 模型的比较来评估模型性能。结果表明，CBCF 火焰中存在 4 个燃料流的 3 个反应阶段，并且一维小火焰和 3D PP-DNS 解决方案中都显示了它们相应的火焰行为明显不同。先验结果表明，煤/生物2Z-FPV模型由于缺乏区分挥发物来源，对瓦斯温度和主要组分的预测会出现较大偏差。相比之下，扩展的 FPV 模型可以很好地重现 CBCF 火焰中复杂燃料流的不同反应阶段的火焰行为（温度和物种分布）。这验证了扩展的 FPV 模型，并证明了其相对于传统 2Z-FPV 模型的优越性。
Coal/biomass co-firing (CBCF) is regarded as one of the sustainable alternatives to reduce emissions from the utilization of fossil fuels. It features complex reacting stages and fuel streams caused by the asynchronous reaction behaviors of coal and biomass particles, which cannot be represented well by the traditional two-mixture-fractions (2Z) coal flamelet/progress variable (FPV) model. To address this issue, we developed an extended FPV model for the CBCF flame in the present study. Firstly, a three-dimensional (3D) point-particle direct numerical simulation (PP-DNS) was conducted to explore the combustion characteristics of the co-firing flame and served as a reference for the model development. Secondly, an extended FPV model was developed by introducing an extra parameter to distinguish the volatiles sources, and the model performance was evaluated by the a p r i o r i study as well as comparison with those of the traditional coal-/bio-2Z-FPV models. The results showed that there were three reacting stages with four fuel streams in the CBCF flame, and their corresponding flame behaviors were obviously different from each other as demonstrated in both the one-dimensional flamelets and 3D PP-DNS solutions. The a p r i o r i results showed that the coal-/bio-2Z-FPV models would give large deviations in the predictions of gas temperature and major species due to the lack of distinguishing the volatiles sources. In contrast, the extended FPV model could well reproduce the flame behaviors (both temperature and species profiles) for different reacting stages with complex fuel streams in the CBCF flame. This validated the extended FPV model and demonstrated its superiority against the traditional 2Z-FPV models.