Chemical Engineering Commons^™

Flow Regimes In Bubble Columns With And Without Internals: A Review, Ayat N. Mahmood, Amer A. Abdulrahman, Laith S. Sabri, Abbas J. Sultan, Hasan Shakir Majdi, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Hydrodynamics characterization in terms of flow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies. This review presents recent studies on the typical flow regimes established in bubble columns. Some effort is also provided to introduce relevant definitions pertaining to this field, namely, that of "void fraction" and related (local, chordal, cross-sectional and volumetric) variants. Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail. In the second part of the review, the attention is shifted to cases with internals of various types (perforated …

Coarsening Dynamics Of Ternary Polymer Solutions With Mobility And Viscosity Contrasts, Jan Ulric Garcia, Douglas R. Tree, Alyssa Bagoyo, Tatsuhiro Iwama, Kris T. Delaney, Glenn H. Fredrickson

Faculty Publications

Using phase-field simulations, we investigate the bulk coarsening dynamics of ternary polymer solutions undergoing a glass transition for two models of phase separation: diffusion only and with hydrodynamics. The glass transition is incorporated in both models by imposing mobility and viscosity contrasts between the polymer-rich and polymer-poor phases of the evolving microstructure. For microstructures composed of polymer-poor clusters in a polymer-rich matrix, the mobility and viscosity contrasts significantly hinder coarsening, effectively leading to structural arrest. For microstructures composed of polymer-rich clusters in a polymer-poor matrix, the mobility and viscosity contrasts do not impede domain growth; rather, they change the transient …

Development, Validation And Implementation Of Multiple Radioactive Particle Tracking Technique, Mehul S. Vesvikar, Thaar M. Aljuwaya, Mahmoud M. Taha, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Computer Automated Radioactive Particle Tracking (CARPT) technique has been successfully utilized to measure the velocity profiles and mixing parameters in different multiphase flow systems where a single radioactive tracer is used to track the tagged phase. However, many industrial processes use a wide range of particles with different physical properties where solid particles could vary in size, shape and density. For application in such systems, the capability of current single tracer CARPT can be advanced to track more than one particle simultaneously. Tracking multiple particles will thus enable to track the motion of particles of different size shape and density, …

Integration Of Dynamic Growth Modeling And Hydrodynamics In An Internal-Loop Split Photobioreactor, Laith S. Sabri, Aastha Ojha, Abbas J. Sultan, Muthanna H. Aldahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

In this study, new high-quality experimental data for culturing green microalgae Scenedesmus in tubular and cylindrical split airlift photobioreactors were obtained under different operating conditions. The obtained experimental data of culturing microalgae Scenedesmus in a tubular photobioreactor were used for determining the kinetic parameters of the photosynthetic reaction. On the other hand, the culturing of green microalgae in a split airlift photobioreactor was used to measure the microalgae cell trajectory using an advanced radioactive particle tracking (RPT) technique. The obtained results in terms of kinetic parameters of the photosynthetic reaction and microalgae cell trajectory were integrated for the first time …

Random Trilobe Packing Using Rigid Body Approach And Local Gas-Liquid Hydrodynamics Simulation Through Cfd With Experimental Validation, Binbin Qi, Sebastián Uribe, Omar Farid, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

It is quite difficult to measure the local information of the gas/liquid flow inside random packed extrudate catalyst beds in a large scale. Obtaining the local information through computational fluid dynamic (CFD) simulations in such system is also difficult due to the complexity of random particle packing and two-phase flow simulation. An efficient packing scheme was implemented to randomly pack 2917 trilobe particles (10 cm in height) in a 2-inch column to represent the trickle bed reactor (TBR) based on the rigid body approach. The generated geometry was used to define the computational domain for the two-phase hydrodynamics simulation based …

Local Time-Averaged Gas Holdup In Fluidized Bed Reactor Using Gamma Ray Computed Tomography Technique (Ct), Abdelsalam Efhaima, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Many Invasive and Non-Invasive Techniques Have Been Used to Analyze the Hydrodynamics of Fluidized Beds. in This Study, the Effect of Superficial Gas Velocity and Bed Particle Density on the Hydrodynamics of Gas–solid Fluidized Beds Was Investigated by using a Cylindrical Plexiglas Fluidized Bed Column, 14 Cm in Diameter. Air at Room Temperature Was Used as the Fluidizing Gas and Two Different Geldart Type-B Particles Were Used: Glass Beads and Copper Particles with Material Densities of 2.5 and 5.3 G/cm3, Respectively, with the Same Size Particle, 210 µm. to Measure the Time-Averaged Cross-Sectional Gas and Solid Holdup Distribution, Gamma Ray …

Multiphase Hydrodynamics And Distribution Characteristics In A Monolith Bed Measured By Optical Fiber Probe, Yuan Zhou, Milorad P. Dudukovic, Muthanna H. Al-Dahhan, Hui Liu

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Optical Fiber Probe Has Been for the First Time Applied to Investigate the Hydrodynamics and Gas-Phase Distribution at High Gas/liquid Ratios in a Two-Phase Flow Monolith Bed with 0.048 M Diameter and 400 Cpsi. Local Hydrodynamic Parameters Including Gas Holdup, Bubble Frequency, Bubble Velocity, and Bubble Length in Single Channels Were Measured by 16 Inserted Single-Point Optical Fiber Probes within the Bed under a Nozzle as the Liquid Distributor. the Following Findings Are Reported. (1) the Optical Fiber Probe Can Be Used as an Efficient and Convenient Technique for Measuring Local Hydrodynamic Parameters Inside the Channels of a Monolith …

Modeling The Relaxation Time Of Dna Confined In A Nanochannel, Douglas R. Tree, Yanwei Wang, Kevin D. Dorfman

Faculty Publications

Using a mapping between a Rouse dumbbell model and fine-grained Monte Carlo simulations, we have computed the relaxation time of λ-DNA in a high ionic strength buffer confined in a nanochannel. The relaxation time thus obtained agrees quantitatively with experimental data [Reisner et al., Phys. Rev. Lett. 94, 196101 (2005)] using only a single O(1) fitting parameter to account for the uncertainty in model parameters. In addition to validating our mapping, this agreement supports our previous estimates of the friction coefficient of DNA confined in a nanochannel [Tree et al., Phys. Rev. Lett. 108, 228105 …

Is Dna A Good Model Polymer?, Douglas R. Tree, Abhiram Muralidhar, Patrick S. Doyle, Kevin D. Dorfman

Faculty Publications

The details surrounding the crossover from wormlike-specific to universal polymeric behavior has been the subject of debate and confusion even for the simple case of a dilute, unconfined wormlike chain. We have directly computed the polymer size, form factor, free energy, and Kirkwood diffusivity for unconfined wormlike chains as a function of molecular weight, focusing on persistence lengths and effective widths that represent single-stranded and double-stranded DNA in a high ionic strength buffer. To do so, we use a chain-growth Monte Carlo algorithm, the pruned-enriched Rosenbluth method (PERM), which allows us to estimate equilibrium and near-equilibrium dynamic properties of wormlike …

A New Method For Online Flow Regime Monitoring In Bubble Column Reactors Via Nuclear Gauge Densitometry, Ashfaq Shaikh, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

In the Current Work, Nuclear Gauge Densitometry (NGD), Which is Commercially Available and Industrially Used for Liquid/slurry Level Measurement and Control, Has Been Employed to Identify Fingerprints of the Prevailing Hydrodynamic Flow Regime. Experiments Were Performed using an Air-Water System in 0.1012. M Diameter and 1.2. M Long Bubble Column at Ambient Pressure. the Superficial Gas Velocities Were Varied from 1. Cm/s to 12. Cm/s with an Interval of 0.5. Cm/s Near Transition Region. the Flow Regime Boundaries Were Defined using the Conventional Methods of Flow Regime Demarcation Such as the Change in the Slope of the overall Gas Holdup …

Airlift Column Photobioreactors For Porphyridium Sp. Culturing: Part I. Effects Of Hydrodynamics And Reactor Geometry, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Photosynthetic Microorganisms Have Been Attracting World Attention for their Great Potential as Renewable Energy Sources in Recent Years. Cost Effective Production in Large Scale, However, remains a Major Challenge to overcome. It is Known to the Field that Turbulence Could Help Improving the Performance of Photobioreactors Due to the So-Called Flashing Light Effects. Better Understanding of the Multiphase Fluid Dynamics and the Irradiance Distribution Inside the Reactor that Cause the Flashing Light Effects, as Well as Quantifying their Impacts on the Reactor Performance, Thus, Are Crucial for Successful Design and Scale-Up of Photobioreactors. in This Study, a Species of Red …

Influence Of Solid-Phase Wall Boundary Condition On Cfd Simulation Of Spouted Beds, Xingying Lan, Chunming Xu, Jinsen Gao, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Influence of Solid-Phase Wall Boundary Condition in Terms of Specularity Coefficient and Particle-Wall Restitution Coefficient on the Flow Behavior of Spouted Beds Was Investigated using Two-Fluid Model Approach in the Computational Fluid Dynamics Software FLUENT 6.3. Parametric Studies of Specularity Coefficient and Particle-Wall Restitution Coefficient Were Performed to Evaluate their Effects on the Flow Hydrodynamics in Terms of Fountain Height, Spout Diameter, Pressure Drop, Local Voidage and Particles Velocity. the Numerical Predictions Were Compared with Available Experimental Data in the Literatures to Obtain the Suitable Values of Specularity Coefficient and Particle-Wall Restitution Coefficient for Spouted Beds. the Simulated Results …

Airlift Column Photobioreactors For Porphyridium Sp. Culturing: Part Ii. Verification Of Dynamic Growth Rate Model For Reactor Performance Evaluation, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Dynamic Growth Rate Model Has Been Developed to Quantify the Impact of Hydrodynamics on the Growth of Photosynthetic Microorganisms and to Predict the Photobioreactor Performance. Rigorous Verification of Such Reactor Models, However, is Rare in the Literature. in This Part of Work, Verification of a Dynamic Growth Rate Model Developed in Luo and Al-Dahhan (2004) [Biotech Bioeng 85(4): 382-393.] Was Attempted using the Experimental Results Reported in Part I of This Work and Results from Literature. the Irradiance Distribution Inside the Studied Reactor Was Also Measured at Different Optical Densities and Successfully Correlated by the Lambert-Beer Law. When Reliable Hydrodynamic …

Local Gas Holdup In A Draft Tube Airlift Bioreactor, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Airlift Column Bioreactors Are Gas-Liquid Contact Devices Characterized by a Rising Channel and a Down Flow Channel Due to Gas Holdup Differences in These Two Channels. Local Gas Holdup Distribution Strongly Affects the overall Gas-Liquid Flow Dynamics in Airlift Columns. in This Work, Local Gas Holdup Distributions in a Draft Tube Airlift Column Covering Both Bubbly Flow and Churn-Turbulent Flow Regimes Have Been Studied using Computed Tomography (CT) Technique as Well as Conventional Techniques. the Radial and Axial Evolutions of the Gas Holdup Distribution Will Be Discussed, Together with the Effects of Superficial Gas Velocity and Geometry Parameters. the Obtained …

Study Of The Minimum Spouting Velocity In A Draft Tube Conical Spouted Bed, Haritz Altzibar, G. Lopez, M. Olazar, J. Bilbao

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering

A study has been carried out on the hydrodynamics of conical spouted beds with a non-porous draft-tube. A hydrodynamic correlation has been proposed for calculating the minimum spouting velocity as a function of dimensionless moduli that take into account geometric factors, particle characteristics and operating conditions. A statistical analysis of the data obtained following a design of experiments shows that the inlet diameter, particle diameter and the height of the entrainment zone are the parameter of greater influence on the minimum spouting velocity.

Numerical Computation Of Hydrodynamic Behavior Of Biomass Particles In Circulating Fluidized Beds, Afsin Gungor Dr.

The 13th International Conference on Fluidization - New Paradigm in Fluidization Engineering

A model using a particle based approach is developed to accurately predict the hydrodynamic behavior of biomass particles in CFBs. Generally, the change in the pressure gradient with height in CFB riser is small. Numerical results are in good agreement with experiments, both in form and magnitude.

Local Characteristics Of Hydrodynamics In Draft Tube Airlift Bioreactor, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Airlift Column Reactors Have Been Widely Used in Bioprocesses. the Design, Scale-Up, and Performance Evaluation of Such Reactors All Require Extensive and Accurate Information About the Gas-Liquid Flow Dynamics, Particularly as Computational Fluid Dynamics (CFD) Has Become More Popular in the Last Decade. However, Due to the Limitation of Most Conventional Techniques for Gas-Liquid Flow Dynamics Measurement, Only Global Hydrodynamic Parameters (E.g., Cross-Sectionally Averaged Liquid Circulation Velocity, overall Gas Holdup, and overall Mass Transfer Rate) Have Been Extensively Studied. the Local Flow Characteristics (E.g., the Macro-Mixing and the Turbulence Intensity) Remain Unclear. in This Study, We Use the Computer Automated …

Macro-Mixing In A Draft-Tube Airlift Bioreactor, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Airlift Reactors Are Pneumatically Agitated Reactors that Have Been Widely Used in Industries, Particularly in Bioprocesses. Extensive Studies About the Flow Dynamics in Airlift Column Reactors Exist; However, Most of These Studies Have Focused on Global Hydrodynamic Parameters using Conventional Techniques. the Local Flow Characteristics, such as the Macro-Mixing and the Turbulence Intensity, Are Crucial for Reliable Design and Scale-Up, and They Remain Unclear. This Work Focuses on Studying the Macro-Mixing in a Draft-Tube Airlift Bioreactor Utilizing an Advanced Flow Dynamic Measurement Technique, Computer Automated Radioactive Particle Tracking (CARPT). True Residence Time Distribution Analyses for the overall Column as Well …

Hydrodynamic Characteristics Of A Fluidized Bed With Rotating Distributor, C. Sobrino, S. Sánchez-Delgado, J. A. Almendros-Ibáñez, M. De Vega, U. Ruiz-Rivas, D. Santana

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The performance of a novel rotating distributor fluidized bed is presented. The pressure drop and the standard deviation of pressure fluctuations, σp, were used to find the minimum fluidization velocity, Umf, and to characterize the quality of fluidization at different rotational speeds of the distributor plate. Experiments were conducted in the freely bubbling regime in a 0.19 m i.d. fluidized bed, operating with Group B particles according to Geldart’s classification. A decrease in Umf is observed when the rotational speed increases. Frequency analysis of pressure fluctuations shows that fluidization can be controlled by the adjustable rotational speed, at several excess …

Understanding The Hydrodynamics In A 2-Dimensional Downer By Cfd-Dem Simulation, Yongzhi Zhao, Yi Cheng, Yulong Ding, Yong Jin

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The gas-solid flows in a 2-dimensional downer were simulated using a CFD-DEM method. The predicted macro-scale flow structure had good agreement with the experiments. The distinct clustering phenomena at meso-scale were revealed throughout the downer. Influences of the collision properties of the wall and the particles on the hydrodynamics in downer were investigated.

The Influence Of Distributor Design On Fluidized Bed Dryer Hydrodynamics, Michael Wormsbecker, Todd S. Pugsley, Helen Tanfara

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The influence of perforated plate, punched plate and Dutch weave mesh distributor designs on fluidized bed dryer hydrodynamics was studied for a range of bed loadings and superficial gas velocities. The punched plate performs better than the other designs at a gas velocity of 1.5 m/s and bed loadings greater than 1.0 kg.

Four Approaches To Structure Gas-Solid Fluidized Beds, J. Ruud Van Ommen, John Nijenhuis, Marc-Olivier Coppens

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Structuring fluidized beds can facilitate scale-up and increase conversion and selectivity by controlling the bubble size. We present four approaches to structure fluidized beds: oscillating the gas flow, distributing the gas injection, imposing an electric field to induce interparticle forces, and optimising distributed particle properties such as the size.

Tailoring Particle Mixtures For Fluidized Bed Reactors Using High-Throughput Experimentation, John Nijenhuis, J. Ruud Van Ommen

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The goal of the described project is to design mixtures of particles with optimal fluidization properties. Using high-throughput experimentation, a novel approach for hydrodynamic research, the relevant properties can be obtained in a limited period of time. This approach is demonstrated by measuring the hydrodynamic characteristics of typical Geldart B powders.

Bubble Size And Mass Transfer In A Modified Airlift Loop Reactor With Continuous Slurry Phase, Mengxi Liu, Chunxi Lu, Mingxian Shi

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A modified internal airlift loop reactor with continuous slurry phases was explored to investigate the local bubble size and the local mass transfer properties. A mathematical model was derived to simulate the bubble size in every flow region. Also, a new method was developed to measure the dissolved oxygen concentration.

Hydrodynamics Of Gas-Solids Bubbling Fluidized Beds Using Polyethylene Resin, Bangyou Wu, John Shepperson, Loni Van Der Lee, Céline Bellehumeur, Apostolos Kantzas

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Pressure fluctuations were measured in three gas-solids bubbling fluidized beds (10cm, 20cm, and 30cm diameter, 1.0m high) using polyethylene particles of different sizes and particle size distributions. Both bed scale and particle size distribution significantly affect the gas-solids flow behavior. Bubble diameters measured from X-ray fluoroscopy in the 10cm diameter column were compared to various correlations in the literature.

Laser Diagnostics Of Hydrodynamics And Gas-Mixing In The Splash Zone Of Gas-Fluidized Beds, Roberto Solimene, Antonio Marzocchella, Raffaele Ragucci, Piero Salatino

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

The hydrodynamic patterns of gas flow associated with bubbles bursting at the surface of gas-fluidized beds have been investigated by means of planar laser induced fluorescence using acetone as diffusive gas tracer. The flow structures generated by the eruption of an isolated bubble have been characterized as a function of bed material size and of bubble injection level.

X-Ray Fluoroscopy Measurements And Cfd Simulation Of Hydrodynamics In A Two Dimensional Gas-Solids Fluidized Bed, Zhengxing He, Bangyou Wu, Blake Chandrasekaran, Celine Bellehumeur, Apostolos Kantzas

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

X-ray fluoroscopy measurements and CFD simulation were used to characterize the hydrodynamics in a pseudo 2-D gas-solids bubbling fluidized bed using polyethylene resin and glass beads. Bubble properties, such as bubble frequency, bubble size, bubble number distribution and bubble diameter distribution, were estimated from X-ray images and compared to those from CFD simulation.

Hydrodynamic Aspects And Correlations For The Design Of Draft-Tube Conical Spouted Beds, H. Altzibar, S. Alvarez, M.J. San José, R. Aguado, J. Bilbao, Martin Olazar

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A study has been carried out on the hydrodynamics of conical spouted beds with draft tube. Correlations have been proposed for calculating minimum spouting velocity, operating pressure drop and peak pressure drop as functions of dimensionless module that take into account geometric factors, particle characteristics and operating conditions.

An Analysis Of Pressure Fluctuations In A Cfb Of Heavy Minerals, Adam Luckos, Quinn G. Reynolds , Paul Den Hoed

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

Pressure fluctuations were measured at high frequencies in a CFB model operated with air at ambient conditions. The model comprises an 80-mm-ID, 5-m-tall riser with a blind-T exit, a cyclone, a 50-mm-ID standpipe, and an L-valve. Tests were conducted with particles of natural rutile (TiO2), a heavy mineral mined from coastal dunes. The particles fall into group B of Geldart’s classification. The solids inventory was kept at 25 kg. The superficial gas velocity ranged from 3 to 6 m/s. The solid circulation flux varied between 10 and 40 kg/m2.s.

Profiles of solid concentrations in the riser are C-shaped. The amplitude …

Hydrodynamic Scale-Up Of Circulating Fluidized Beds, Ted Knowlton, S. B. Reddy Karri, J. S. Smith

The 12th International Conference on Fluidization - New Horizons in Fluidization Engineering

A general procedure that can be used to scale up circulating fluidized beds is presented. It consists of developing a mathematical model in conjunction with measuring 1) the radial dispersion coefficient (Dr) using gas tracers, 2) the radial solids velocity profile using a Pitot tube and 3) the radial distribution of solids density (1 - ε) using an optical probe. If the resulting information is obtained in a riser 200 mm or greater in diameter, it can be used in conjunction with the mathematical model for scale-up.