氧含量越高点火越快吗：空气和氧气氛中煤粉颗粒着火数值研究-PRO

题目：空气和氧气氛中煤粉颗粒着火数值研究
摘要：在常规和全氧气氛（oxy-fuel）下，对煤颗粒的着火和燃烧进行了数值研究。使用chemical percolation devolatilization（CPD）模型计算脱挥发分过程。 CPD模型耦合在一个结合拉格朗日粒子追踪方法的多物理场、多尺度Navier–Stokes求解器中，使用有限速率化学反应描述气相燃烧。所得到的颗粒点火数值仿真结果与实验数据比较吻合。评估了不同脱挥发阶段对火焰点火的影响，本文根据脱挥发速率的两个不同峰值划分了颗粒脱挥发阶段，据观察，第一或者第二阶段可能发生燃烧，具体取决于颗粒粒径和气体温度。研究表明，与空气气氛相比，全氧气氛中点火延迟时间的增加与自由基被消耗在同大量二氧化碳的反应中有关，而混合物的热容量的增加并无显著影响

要点
1.欧拉-拉格朗日框架，均匀网格尺寸等于颗粒直径
2.为了解决网格尺度相对颗粒粒径过小而不满足film model假设的问题，设计了一个滤波器，即，CPD模型输入的气相物理量为一个立方体内的平均值，该立方体以颗粒所在位置为中心，边长为
3.气相方程中的来自颗粒的源相分布在一个直径为的球形区域，源相在该区域内的分布服从高斯分布，
图片摘要

初始温度Tg = 1200 K时，空气和全氧气氛中125μm颗粒的最高气体温度的变化/Evolution of the maximum gas temperature for a 125 μm particle in air and oxy-atmosphere with the initial temperature Tg = 1200 K.

Title: Numerical study of coal particle ignition in air and oxy-atmosphere
Abstract: The ignition and combustion of coal particles are investigated numerically under conventional and oxy-fuel atmospheres. Devolatilization is computed using the chemical percolation devolatilization (CPD) model. The CPD model is coupled with a Lagrangian particle tracking method in the framework of a multiphysics, multiscale Navier–Stokes solver. Combustion in the gas phase is described using finite rate chemistry. The numerical results for ignition are compared with available experimental data and a remarkably good agreement is observed. The effect on flame ignition of the different phases characterizing the release of volatile gases is assessed. These different phases manifest themselves in two distinct peaks in the devolatilization rate and it is observed that ignition can occur during the first volatile release or on the onset of the second, depending on the particle size and gas temperature. It is found that an increase of ignition delay time in oxy-atmosphere compared to the air case is related to the depletion of radicals that react with the abundant carbon dioxide of the oxy-atmosphere, while the increased heat capacity of the mixture does not play a role.
原文链接，Proceedings of the Combustion Institute，IF 3.299
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