This paper focuses on a two-dimensional CFD simulation of a downdraft gasifier and a pilot-scale experiment for verification using wood pellet fuel. The simulation work was carried out via the ANSYS-Fluent CFD software package with in-house coding via User Defined Function. Three gasification parameters were taken into account in the simulation and validation to achieve highly accurate results; namely, fuel consumption, temperature profile, and syngas composition. After verification of the developed model, the effects of aspect ratios on temperature and syngas composition were investigated. Results from simulation and experimental work indicated that the fuel consumption rate during the steady state gasification experiment was 1.750 ± 0.048 g/s. The average steady state temperature of the experiment was 1240.32 ± 14.20 K. In sum, the fuel consumption and temperature profile during gasification from modeling and experimentation show an error lower than 1.3%. Concentrations of CO, CO₂, H₂, and CH₄ were 20.42 vol%, 15.09 vol%, 8.02 vol%, and 2.6 vol%, respectively, which are comparable to those of the experiment: 20.00 vol%, 15.48 vol%, 8.00 vol%, and 2.65 vol%. A high concentration of syngas is observed in the outer radial part of the reactor because of the resistive flow of the air inlet and the synthesis gas produced. The average temperatures during the steady state of the gasifier with aspect ratios (H/D) of 1.00, 1.38 (experiment), and 1.82 were 978.77 ± 11.60, 1256.46 ± 9.90, and 1368.94 ± 9.20 K, respectively. The 1.82 aspect ratio reactor has the smallest diameter, therefore the radiative heat transferred from the reactor wall affects the temperature in the reactor. Syngas compositions are comparable. Inverse relationships between the aspect ratios and the syngas LHV, (4.29–4.49 MJ/N m³), cold gas efficiency (29.66% to 31.00%), and carbon conversion (79.59% to 80.87%) are observed.

本文着重于下流气化炉的二维CFD模拟以及用于验证使用木屑燃料的中试规模的实验。仿真工作是通过ANSYS-Fluent CFD软件包进行的，并通过用户定义函数进行了内部编码。在模拟和验证中考虑了三个气化参数，以实现高度准确的结果。即燃料消耗，温度曲线和合成气组成。在验证开发的模型后，研究了纵横比对温度和合成气组成的影响。模拟和实验工作的结果表明，稳态气化实验期间的燃料消耗率为1.750±0.048 g / s。实验的平均稳态温度为1240.32±14.20K。根据建模和实验，气化过程中的燃料消耗和温度曲线显示的误差低于1.3％。一氧化碳浓度₂，H ₂和CH ₄分别为20.42％（体积），15.09％（体积），8.02％（体积）和2.6％（体积），与实验相当：20.00％（体积），15.48％（体积），8.00％（体积）和2.65体积％。由于空气入口和产生的合成气的阻力流，在反应器的径向外部观察到高浓度的合成气。纵横比为H / D的气化炉稳态期间的平均温度），1.00（1.38（实验）和1.82）分别为978.77±11.60、1256.46±9.90和1368.94±9.20 K. 长宽比为1.82的反应堆直径最小，因此从反应堆壁传来的辐射热会影响反应堆中的温度。合成气的组成是可比的。观察到纵横比与合成气LHV（4.29–4.49 MJ / N m ³），冷气效率（29.66％至31.00％）和碳转化率（79.59％至80.87％）之间成反比。