Philadelphia Mixing Solutions Ltd., Palmyra, PA 17078, USA.
Water Res. 2010 Jul;44(13):3861-74. doi: 10.1016/j.watres.2010.04.043.
This paper presents an Eulerian multiphase flow model that characterizes gas mixing in anaerobic digesters. In the model development, liquid manure is assumed to be water or a non-Newtonian fluid that is dependent on total solids (TS) concentration. To establish the appropriate models for different TS levels, twelve turbulence models are evaluated by comparing the frictional pressure drops of gas and non-Newtonian fluid two-phase flow in a horizontal pipe obtained from computational fluid dynamics (CFD) with those from a correlation analysis. The commercial CFD software, Fluent12.0, is employed to simulate the multiphase flow in the digesters. The simulation results in a small-sized digester are validated against the experimental data from literature. Comparison of two gas mixing designs in a medium-sized digester demonstrates that mixing intensity is insensitive to the TS in confined gas mixing, whereas there are significant decreases with increases of TS in unconfined gas mixing. Moreover, comparison of three mixing methods indicates that gas mixing is more efficient than mixing by pumped circulation while it is less efficient than mechanical mixing.
本文提出了一种描述厌氧消化器中气体混合的欧拉多相流模型。在模型开发中，假设液体粪便为水或依赖总固体 (TS) 浓度的非牛顿流体。为了为不同的 TS 水平建立合适的模型，通过将计算流体动力学 (CFD) 获得的气体和非牛顿流体在水平管中的摩擦压降与相关分析进行比较，评估了 12 种湍流模型。商业 CFD 软件 Fluent12.0 用于模拟消化器中的多相流。小型消化器的模拟结果与文献中的实验数据进行了验证。中型消化器中两种气体混合设计的比较表明，在封闭气体混合中，混合强度对 TS 不敏感，而在非封闭气体混合中，混合强度随 TS 的增加而显著降低。此外，三种混合方法的比较表明，与泵送循环混合相比，气体混合效率更高，而与机械混合相比，气体混合效率更低。
