A Numerical Study of the Global Performance of Two Static Mixers

2005 ◽  
Author(s):  
Ramin K. Rahmani ◽  
Anahita Ayasoufi ◽  
Theo G. Keith
Keyword(s):  
Pressure Drop ◽  
Numerical Study ◽  
Critical Role ◽  
Design Procedure ◽  
Static Mixer ◽  
Flowing Fluid ◽  
Viscous Liquids ◽  
Static Mixers ◽  
Wide Range ◽  
Global Performance

Viscous liquids have to be homogenized in continuous operations in many branches of processing industries; and therefore, fluid mixing plays a critical role in the success or failure of many industrial processes. The use of static mixers has been utilized over a wide range of applications from simple blending to complex chemical reactions. Generally, a static mixer consists of a number of equal stationary units, placed on the inside of a pipe or channel in order to promote mixing of flowing fluid streams. These mixers have low maintenance and operating costs, low space requirements and no moving parts. A range of designs exists for a wide range of specific applications. The shape of the elements determines the character of the fluid motion and thus determines the effectiveness of the mixer. There are several key parameters in the design procedure of a static mixer. Some of the most important ones are: the degree of mixing of working fluids, pressure drop across the mixer, and residence time distribution of fluid elements. An ideal static mixer provides a highly mixed material with low pressure drop and similar traveling history for all fluid elements. To choose a static mixer for a given application or in order to design a new static mixer, besides experimentation, it is possible to use powerful computational fluid dynamics (CFD) tools to study the performance of static mixers. This paper extends previous studies by the authors on industrial static mixers and illustrates how static mixing processes of single-phase viscous liquids can be simulated numerically. Using different measuring tools, the global performance and costs of two static mixers are studied.

A Numerical Study on Enhancement of Heat Exchanger Performance by Inserting Static Mixer Elements

2006 ◽  
Author(s):  
Ramin K. Rahmani ◽  
Anahita Ayasoufi ◽  
Theo G. Keith
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Fluid Motion ◽  
Design Procedure ◽  
Static Mixer ◽  
Flowing Fluid ◽  
Static Mixers ◽  
Continuous Mixing ◽  
Wide Range ◽  
Space Requirements

In chemical processing industries, heating, cooling and other thermal processing of viscous fluids are an integral part of the unit operations. Static mixers are often used in continuous mixing, heat transfer, and chemical reactions applications. Generally, a static mixer consists of a number of equal stationary units, placed on the inside of a pipe or channel in order to promote mixing of flowing fluid streams. These mixers have low maintenance and operating costs, low space requirements, and no moving parts. A range of designs exists for a wide range of specific applications. The shape of the elements determines the character of the fluid motion and thus determines the effectiveness of the mixer. There are several key parameters in the design procedure of a static mixer. An ideal static mixer for heat transfer applications provides a higher rate of heat transfer and thermally homogenous fluid with low pressure drop and similar traveling history for all fluid elements. To choose a static mixer for a given application or in order to design a new static mixer, besides experimentation, it is possible to use powerful computational fluid dynamics (CFD) tools to study the performance of static mixers. This paper illustrates how static mixer can improve the performance of heat exchangers. Using different measuring tools, the global performance and costs of two popular commercial static mixers are studied in order to choose the most effective design for thermal applications.

A Numerical Study of the Global Performance of Two Static Mixers

2006 ◽  
Vol 129 (3) ◽  
pp. 338-349 ◽  
Author(s):  
Ramin K. Rahmani ◽  
Anahita Ayasoufi ◽  
Theo G. Keith
Keyword(s):  
Numerical Study ◽  
Shear Thickening ◽  
Static Mixer ◽  
Mixing Processes ◽  
Viscous Liquids ◽  
Static Mixers ◽  
Continuous Mixing ◽  
Mass Transfer Processes ◽  
Global Performance ◽  
Shear Thickening Fluids

The use of in-line static mixers has been widely advocated for an important variety of applications, such as continuous mixing, heat and mass transfer processes, and chemical reactions. This paper extends previous studies by the authors on industrial static mixers and illustrates how static mixing processes of single-phase viscous liquids can be numerically simulated. Mixing of Newtonian, shear-thinning, and shear-thickening fluids through static mixer, as well as thermal enhancement by static mixer is studied. Using different measuring tools, the global performance and costs of SMX (Sulzer mixer X) and helical static mixers are studied. It is shown that the SMX mixer manifests a higher performance; however, the required energy to maintain the flow across a SMX mixer is significantly higher.

A Study of the Accuracy, Global Performance, and Computational Expenses of k–ε, k–ω, and RSM Turbulent Models for Flow in an Industrial Static Mixer

2004 ◽  
Author(s):  
Ramin K. Rahmani ◽  
Theo G. Keith ◽  
Anahita Ayasoufi
Keyword(s):  
Single Phase ◽  
Critical Role ◽  
Three Dimensional ◽  
Static Mixer ◽  
Mixing Processes ◽  
Viscous Liquids ◽  
Pressure Drops ◽  
Wide Range ◽  
Global Performance ◽  
Turbulent Models

Viscous liquids have to be homogenized in continuous operations in many branches of processing industries; and therefore, fluid mixing plays a critical role in the success or failure of many industrial processes. The use of static mixers has been utilized over a wide range of applications such as continuous mixing, blending, heat and mass transfer processes, chemical reactions, etc. Consequences of improper mixing include non-reproducible processing conditions and lowered product quality, resulting in the need for more elaborate downstream purification processes and increased waste disposal costs. This paper extends previous studies by the authors on an industrial helical static mixer and illustrates how static mixing processes of single-phase viscous liquids can be simulated numerically. It also intends to present an improved understanding of the turbulent flow pattern for single-phase liquids through the mixer. Three-dimensional finite volume simulations are used to study the performance of the mixer for a range of practical Reynolds numbers, using three different turbulent models: k–ε model, k–ω model, and RSM model. The accuracy, global performance and costs of the different turbulent models have been examined. The flow velocities, pressure drops, etc. are calculated for each model. The calculated pressure drop of each case is compared with experimental results. Using different tools, the mixing results obtained from the different models are studied and compared.

A Numerical Study of Turbulent Flow in Helical Static Mixers

2006 ◽  
Author(s):  
Ramin K. Rahmani ◽  
Anahita Ayasoufi ◽  
Theo G. Keith
Keyword(s):  
Turbulent Flow ◽  
Molecular Diffusion ◽  
Stokes Equations ◽  
Numerical Study ◽  
Critical Role ◽  
Three Dimensional ◽  
Turbulent Dispersion ◽  
Working Fluid ◽  
Static Mixer ◽  
Static Mixers

Many processing applications call for the addition of small quantities of chemicals to working fluid. Hence, fluid mixing plays a critical role in the success or failure of these processes. An optimal combination of turbulent dispersion down to eddies of the Kolmogoroff scale and molecular diffusion would yield fast mixing on a molecular scale which in turn favors the desired reactions. Helical static mixers can be used for those applications. The range of practical flow Reynolds numbers for these mixers in industry is usually from very small (Re ∼ 0) to moderate values (Re ∼ 5000). In this study, a helical static mixer is investigated numerically using Lagrangian methods to characterize mixer performance under turbulent flow regime conditions. A numerical simulation of turbulent flows in helical static mixers is employed. The model solves the three-dimensional, Reynolds-averaged Navier-Stokes equations, closed with the Spalart-Allmaras turbulence model, using a second-order-accurate finite-volume numerical method. Numerical simulations are carried out for a six-element mixer, and the computed results are analyzed to elucidate the complex, three-dimensional features of the flow. Using a variety of predictive tools, mixing results are obtained and the performance of static mixer under turbulent flow condition is studied.

Large-Eddy Turbulent Flow Simulation of a KOMAX Static Mixer

2008 ◽  
Author(s):  
Ramin K. Rahmani ◽  
Theo G. Keith ◽  
Anahita Ayasoufi
Keyword(s):  
Turbulent Flow ◽  
Critical Role ◽  
Flow Simulation ◽  
Reynolds Numbers ◽  
Static Mixer ◽  
Viscous Liquids ◽  
Pressure Drops ◽  
Static Mixers ◽  
Eddy Simulation ◽  
Large Eddy

Viscous liquids have to be homogenized in continuous operations in many branches of processing industries; and therefore, fluid mixing plays a critical role in the success or failure of many industrial processes. Consequences of improper mixing include non-reproducible processing conditions and lowered product quality, resulting in the need for more elaborate downstream processes and increased costs. The range of practical flow Reynolds numbers for KOMAX static mixers in industry is usually from moderate values (Re ≈ 0) to very large values (e.g. Re ≈ 5,000,000). However, most of industrial applicants have a very small flow to moderate Reynolds numbers (e.g. Re ≈ 5,000). This paper presents an improved understanding of the turbulent flow pattern for single-phase liquids through the mixer. Large-Eddy Simulation (LES) model is applied to the flow in a KOMAX static mixer to calculate the flow velocities, pressure drops, etc. Using a variety of predictive tools, the mixing results are obtained.

scholarly journals Three-Dimensional Numerical Simulation and Performance Study of an Industrial Helical Static Mixer

2005 ◽  
Vol 127 (3) ◽  
pp. 467-483 ◽  
Author(s):  
Ramin K. Rahmani ◽  
Theo G. Keith ◽  
Anahita Ayasoufi
Keyword(s):  
Turbulent Flow ◽  
Turbulent Flows ◽  
Stokes Equations ◽  
Critical Role ◽  
Three Dimensional ◽  
Static Mixer ◽  
Performance Study ◽  
Mixing Processes ◽  
Viscous Liquids ◽  
Wide Range

In many branches of processing industries, viscous liquids need to be homogenized in continuous operations. Consequently, fluid mixing plays a critical role in the success or failure of these processes. Static mixers have been utilized over a wide range of applications such as continuous mixing, blending, heat and mass transfer processes, chemical reactions, etc. This paper describes how static mixing processes of single-phase viscous liquids can be simulated numerically, presents the flow pattern through a helical static mixer, and provides useful information that can be extracted from the simulation results. The three-dimensional finite volume computational fluid dynamics code used here solves the Navier-Stokes equations for both laminar and turbulent flow cases. The turbulent flow cases were solved using k-ω model and Reynolds stress model (RSM). The flow properties are calculated and the static mixer performance for different Reynolds numbers (from creeping flows to turbulent flows) is studied. A new parameter is introduced to measure the degree of mixing quantitatively. Furthermore, the results obtained by k-ω and RSM turbulence models and various numerical details of each model are compared. The calculated pressure drop is in good agreement with existing experimental data.

scholarly journals Numerical Study of Viscous Fluid Flows in a Kenics Static Mixer

Mechanika ◽  
2020 ◽  
Vol 26 (3) ◽  
pp. 206-211
Author(s):  
Cherif BELHOUT ◽  
Mohamed BOUZIT ◽  
Brahim MENACER ◽  
Youcef KAMLA ◽  
Houari AMEUR
Keyword(s):  
Pressure Drop ◽  
Cfd Simulation ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Fluid Flows ◽  
Static Mixer ◽  
Static Mixers ◽  
Cosmetic Industry ◽  
Dynamic Software ◽  
Computational Fluid Dynamic Software

Since many years static mixers find usage in chemical, food, cosmetic and pharmaceutical industry. One of the most commonly used is the Kenics type static mixer. In a framework of the current work the CFD simulation for Kenics static mixer were performed. In food or cosmetic industry one must deal very often with non-Newtonian fluids. Therefore this work concerns the numerical study of non-Newtonian fluid flux in a kenics km static mixer with laminar flow using the Navier-Stocks equation governing the phenomenon and the pressure loss equation. This simulation was made using the computational fluid dynamic software (CFX 12.0). In this paper we studied the influence of the Reynolds number, the viscosity of the fluid, aspect ratio and the number of helical elements fixed on the pressure drop. It was found that the CFD results of pressure drop for non-Newtonian power law was similar to literature data (the correlation of C.D.GRACE 1971 and the numerical simulation of E.SAATDJIAN 2012).

scholarly journals Three-Dimensional Numerical Simulation and Performance Study of an Industrial Helical Static Mixer

2003 ◽  
Author(s):  
Ramin K. Rahmani ◽  
Theo G. Keith ◽  
Anahita Ayasoufi
Keyword(s):  
Turbulent Flow ◽  
Single Phase ◽  
Stokes Equations ◽  
Critical Role ◽  
Three Dimensional ◽  
Static Mixer ◽  
Performance Study ◽  
Mixing Processes ◽  
Viscous Liquids ◽  
Wide Range

Viscous liquids have to be homogenized in continuous operations in many branches of processing industries. Consequently, fluid mixing plays a critical role in the success or failure of many industrial processes. The use of static mixers has been utilized over a wide range of applications such as continuous mixing, blending, heat and mass transfer processes, chemical reactions, etc. This paper illustrates how static mixing processes of single-phase viscous liquids can be simulated numerically, and presents the flow pattern of both Newtonian and non-Newtonian single-phase liquids through a helical static mixer, and provides useful information that can be extracted from the simulation results. Three-dimensional finite volume simulations are used to study the performance of the mixer. The CFD code used here solves the Navier-Stokes equations for both laminar and turbulent flow cases. The turbulent flow cases were solved using k–ω and Reynolds Stress models. The flow properties are calculated for both Newtonian and non-Newtonian fluids. The calculated pressure drop is in good agreement with existing experimental data.

Simulation of the Laminar Flow in a PRIMIX Static Mixer

2002 ◽  
Author(s):  
R. F. Mudde ◽  
C. Van Pijpen ◽  
R. Beugels
Keyword(s):  
Pressure Drop ◽  
Particle Tracking ◽  
Experimental Validation ◽  
Independent Solution ◽  
High Accuracy ◽  
Static Mixer ◽  
Laminar Regime ◽  
Time Step ◽  
Static Mixers ◽  
Direct Use

The PRIMIX helical static mixer has been investigated using numerical simulations. The flow is in the laminar regime (Re = 1 to 1000). The simulations concentrate on the pressure drop and on the use of particle tracking for mixing studies. For the pressure drop, experimental validation is provided. It is found that the pressure drop can be simulated with high accuracy for Re < 350. For higher Re-values no grid independent solution could be obtained and the experimental results no longer agree with those of the simulations. The simulated pressure drop results scaled to the empty pipe pressure drop, can be well summarized as K = 4.99 + Re/31.4. Using Particle Tracking it has been possible to reproduce literature data. However, it has been shown that the obtained results are rather sensitive to the choice of the time step. This limits the direct use of particle tracking techniques for studying the mixing of static mixers in the laminar regime.

Analysis of the Pressure Drop of the Horizontal Liquid-Solid Circulation Fluidization Bed with Kenics Static Mixers

2013 ◽  
Vol 291-294 ◽  
pp. 791-794
Author(s):  
Yan Liu ◽  
Shao Feng Zhang ◽  
Jiang Tao Wang
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Friction Factor ◽  
Static Mixer ◽  
Experiment Data ◽  
Dimensionless Parameters ◽  
Static Mixers ◽  
Dimensionless Pressure ◽  
Dimension Analysis

In order to obtain the pressure drop of the horizontal liquid-solid circulation fluidization bed with Kenics static mixers, experiments were carried out in four Kenics static mixers with different aspect ratio of mixing element(AR) over a range of 30000 to 51000 to get pressure drop data. Dimension analysis revealed that the pressure drop characteristic of the Kenics static mixer can be described by three dimensionless parameters, such as the friction factor, Reynolds number, and aspect ratio of mixing element. According to the experiment data, a new dimensionless pressure drop correlation was developed. The results indicate that the value of Cf becomes constant and has no correlation with the value of Re in fixed AR. The value of Cf was increased with the increase of AR.

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