Abstract The biomass gasification process in fixed bed was studied by means of computational fluid dynamics (CFD) numerical analysis. The aim was to evaluate the effect of the biomass packing factor on the thermochemical process. The fuel-wood used was Jacaranda Copaia in various shapes: chips, cylinders, and cubes with packing factors (PF) of 0.38, 0.48, and 0.59, respectively. The mathematical model is a transient 2D CFD model, which was developed through the implementation of User Defined Functions in ANSYS-Fluent. The model was extended to simulate the gasification process by expanding the chemical kinetic mechanism and by adapting the stages of pyrolysis, oxidation, and reduction. The model was validated with experimental data. The average relative error between experimental and numerical data was 5.45%. By means of the sensitivity analysis, it was found that with an increase in the packing factor from 0.38 to 0.59, the absorption of radiative heat transfer increases by 27% leading to increase the solid temperature in the reaction front, but due to a lower penetration of radiation, the drying and pyrolysis reaction rates decrease. But nevertheless, the higher solid temperature with packing factor favors the convective solid-gas heat transfer in the drying stage.

中文翻译：

---

固定床气化过程中木材生物质填料因子的数值分析

摘要 采用计算流体动力学（CFD）数值分析方法研究了固定床生物质气化过程。目的是评估生物质堆积因子对热化学过程的影响。所使用的薪材是各种形状的 Jacaranda Copaia：碎片、圆柱体和立方体，填充因子 (PF) 分别为 0.38、0.48 和 0.59。数学模型是瞬态 2D CFD 模型，它是通过在 ANSYS-Fluent 中实现用户定义函数而开发的。该模型通过扩展化学动力学机制和调整热解、氧化和还原阶段，扩展到模拟气化过程。该模型通过实验数据进行了验证。实验数据和数值数据之间的平均相对误差为 5.45%。通过敏感性分析，发现随着填充因子从 0.38 增加到 0.59，辐射传热的吸收增加了 27%，导致反应前沿的固体温度升高，但由于辐射渗透率降低，干燥和热解反应速率下降。但尽管如此，具有填充因子的较高固体温度有利于干燥阶段的对流固气传热。