Abstract This research describes a simulation based on three dimensional computational fluid dynamics (CFD) in a semi-continuous PFR reactor. The commercial software FLUENT 6.3 was employed to solve the governing equations. The gas-liquid flow was modeled using an Eulerian multiphase and k–e turbulence (RNG) model. Hydrodynamics investigated for different total solid (TS) levels and mixing regime using multiple reference frame (MRF) model within the whole multiphase bioreactor. The simulation results in a prototype reactor are validated against the experimental data. Simulation results indicate that flow pattern within the reactor was highly influenced by the substrate density and viscosity, and stirring intensity. Moreover, substrate density and viscosity are variable according to the TS content. The results demonstrate adequate mixing process providing the required amount and intensity of mixing for uniform distribution of reactor content and needed conditions to improve the reactor performance. Comparison of three impeller mixing speed in a reactor demonstrates that mixing intensity has affected the gas phase above the fluid surface. Such a mixing intensity may create a turbulent region with a homogenous mixture of gas and liquid, which is not suitable for this anaerobic digestion.

中文翻译：

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新型径向混合活塞流反应器原型中流体流动的 CFD 模拟

摘要 本研究描述了半连续 PFR 反应器中基于三维计算流体动力学 (CFD) 的模拟。使用商业软件 FLUENT 6.3 来求解控制方程。气液流动使用欧拉多相和 k-e 湍流 (RNG) 模型进行建模。在整个多相生物反应器中使用多参考框架 (MRF) 模型研究了不同总固体 (TS) 水平和混合方案的流体动力学。原型反应器中的模拟结果根据实验数据进行了验证。模拟结果表明反应器内的流动模式受基材密度和粘度以及搅拌强度的影响很大。此外，基材密度和粘度根据 TS 含量而变化。结果表明，充分的混合过程提供了用于均匀分布反应器内容物所需的混合量和强度，以及改进反应器性能所需的条件。反应器中三种叶轮混合速度的比较表明混合强度影响了流体表面上方的气相。这种混合强度可能会产生气体和液体的均匀混合物的湍流区域，这不适合这种厌氧消化。