In terms of gas holdup, liquid velocity, and volumetric mass transfer coefficient for oxygen (K_La), the hydrodynamic behavior of four configurations of an airlift reactor (ALR) with a net draft tube (NDT) of different net mesh sizes (ALR-NDT-3, 6, 12, and ALR) have been numerically simulated for a range of inlet air flow rates. The effect of various levels of ratio of height (H) to inner tube diameter (D) of the net draft tube (H/D: 9.3, 10.7, 17.5, and 20) and ratio of inner cross-sectional area of the riser (A_r) to the inner cross sectional area of the downcomer (A_d) (A_d/A_r: 1.3 and 7) for different air flow rates is also evaluated for each reactor configuration operating with an air–water system. The two-fluid formulation coupled with the k–ε turbulence model is used for computational fluid dynamics (CFD) analysis of flow with Eulerian descriptions for the gas and liquid phases. Interactions between air bubbles and liquid are taken into account using momentum exchange and drag coefficient based on two different correlations. Trends in the predicted dynamical behavior are similar to those found experimentally. A good agreement was achieved suggesting that geometric effects are properly accounted for by the CFD model. After a comparison with experimental data, numerical simulations show significant enhanced gas holdup, liquid velocity, and K_La for the ALR-NDTs compared with the conventional ALR. Higher gas holdup values are achieved for ALR-NDT-3 than that for the other ALRs because it acts like a bubble column reactor as the holes present in the NDT are large. Maximum liquid velocities are seen in ALR-NDT-12, which operates like a conventional ALR. Moreover, the interaction between the NDT and upward gas flow leads to cross flow through the net, small bubbles, and high interfacial area as well as good mass transfer. This was significant in ALR-NDT-6 with maximum K_La value of 0.031 s⁻¹. The applied methodology provides an insightful understanding of the complex dynamic behavior of ALR-NDTs and may be helpful in optimizing the design and scale-up of reactors.

在气体滞留率，液体速度和氧气的体积传质系数（K _L a）方面，具有不同净筛孔尺寸（ALR）的净引流管（NDT）的气举反应器（ALR）的四种配置的流体力学行为-NDT-3、6、12和ALR）已针对一系列进气流量进行了数值模拟。净吃水管的高度（H）与内管直径（D）的比率（H / D：9.3、10.7、17.5和20）和立管的内部截面积之比（H / D）的不同水平的影响甲_{- [R} ），以在降液管（的内横截面面积甲_d）（甲_d /对于使用空气-水系统运行的每种反应堆配置，还评估了不同空气流量的_r：1.3和7）。双流体制剂加上ķ - ε湍流模型用于对流体进行计算流体动力学（CFD）分析，并以欧拉描述为气相和液相。基于两个不同的相关性，使用动量交换和阻力系数考虑了气泡和液体之间的相互作用。预测的动态行为趋势与实验发现的趋势相似。达成了良好的协议，表明CFD模型已适当考虑了几何效应。与实验数据进行比较后，数值模拟表明气体滞留率，液体速度和K _L显着提高。与常规ALR相比，ALR-NDT的a值更高。与其他ALR相比，ALR-NDT-3可获得更高的气体保持率，因为它的作用类似于气泡塔反应器，因为NDT中的孔洞很大。在ALR-NDT-12中可以看到最大的液体速度，其运行方式与常规ALR相似。而且，NDT和向上气流之间的相互作用导致穿过净的横流，小气泡，高界面面积以及良好的质量传递。这在ALR-NDT-6中是显着的，最大K _L a值为0.031 s ^-1。所采用的方法学对ALR-NDT的复杂动态行为提供了深刻的了解，并且可能有助于优化反应堆的设计和放大。