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Records with Keyword: Mixing
Optimization of Reaction Selectivity Using CFD-Based Compartmental Modeling and Surrogate-Based Optimization
Shu Yang, San Kiang, Parham Farzan, Marianthi Ierapetritou
April 9, 2019 (v1)
Keywords: CFD-simulation, compartmental modeling, competing reaction system, Mixing, model order reduction, Optimization, surrogate-based optimization
Mixing is considered as a critical process parameter (CPP) during process development due to its significant influence on reaction selectivity and process safety. Nevertheless, mixing issues are difficult to identify and solve owing to their complexity and dependence on knowledge of kinetics and hydrodynamics. In this paper, we proposed an optimization methodology using Computational Fluid Dynamics (CFD) based compartmental modelling to improve mixing and reaction selectivity. More importantly, we have demonstrated that through the implementation of surrogate-based optimization, the proposed methodology can be used as a computationally non-intensive way for rapid process development of reaction unit operations. For illustration purpose, reaction selectivity of a process with Bourne competitive reaction network is discussed. Results demonstrate that we can improve reaction selectivity by dynamically controlling rates and locations of feeding in the reactor. The proposed methodology inco... [more]
Temporal Mixing Behavior of Conservative Solute Transport through 2D Self-Affine Fractures
Zhi Dou, Brent Sleep, Pulin Mondal, Qiaona Guo, Jingou Wang, Zhifang Zhou
April 8, 2019 (v1)
Subject: Other
Keywords: conservative solute, fractal, fracture, Mixing, roughness
In this work, the influence of the Hurst exponent and Peclet number (Pe) on the temporal mixing behavior of a conservative solute in the self-affine fractures with variable-aperture fracture and constant-aperture distributions were investigated. The mixing was quantified by the scalar dissipation rate (SDR) in fractures. The investigation shows that the variable-aperture distribution leads to local fluctuation of the temporal evolution of the SDR, whereas the temporal evolution of the SDR in the constant-aperture fractures is smoothly decreasing as a power-law function of time. The Peclet number plays a dominant role in the temporal evolution of mixing in both variable-aperture and constant-aperture fractures. In the constant-aperture fracture, the influence of Hurst exponent on the temporal evolution of the SDR becomes negligible when the Peclet number is relatively small. The longitudinal SDR can be related to the global SDR in the constant-aperture fracture when the Peclet number is... [more]
Rotor-Stator Mixers: From Batch to Continuous Mode of Operation—A Review
Andreas Håkansson
July 31, 2018 (v1)
Keywords: batch, continuous, emulsification, high shear mixer, inline, Mixing, rotor-stator mixer
Although continuous production processes are often desired, many processing industries still work in batch mode due to technical limitations. Transitioning to continuous production requires an in-depth understanding of how each unit operation is affected by the shift. This contribution reviews the scientific understanding of similarities and differences between emulsification in turbulent rotor-stator mixers (also known as high-speed mixers) operated in batch and continuous mode. Rotor-stator mixers are found in many chemical processing industries, and are considered the standard tool for mixing and emulsification of high viscosity products. Since the same rotor-stator heads are often used in both modes of operation, it is sometimes assumed that transitioning from batch to continuous rotor-stator mixers is straight-forward. However, this is not always the case, as has been shown in comparative experimental studies. This review summarizes and critically compares the current understandin... [more]
Extending Applications of High-Pressure Homogenization by Using Simultaneous Emulsification and Mixing (SEM)—An Overview
Vanessa Gall, Marc Runde, Heike P. Schuchmann
July 30, 2018 (v1)
Keywords: Energy Efficiency, high-pressure homogenization, Mixing, Process Intensification, process modifications
Conventional high-pressure homogenization (HPH) is widely used in the pharmaceutical, chemical, and food industries among others. In general, its aim is to produce micron or sub-micron scale emulsions with excellent product characteristics. However, its energy consumption is still very high. Additionally, several limitations and boundaries impede the usage of high-pressure homogenization for special products such as particle loaded or highly concentrated systems. This article gives an overview of approaches that have been used in order to improve the conventional high-pressure homogenization process. Emphasis is put on the ‘Simultaneous Emulsification and Mixing’ process that has been developed to broaden the application areas of high-pressure homogenization.
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