Rotating Disk Reactor Research Articles

High local supersaturation formation for precipitated calcium carbonate synthesis by applying a rotating disk reactor

High local supersaturation formation for precipitated calcium carbonate synthesis by applying a rotating disk reactor

Simulation study on mass transfer characteristics and disk structure optimization of a rotating disk reactor with high viscosity region

AbstractDue to the excellent film‐forming specific surface area of the disk reactor, its application in the polymer devolatilization process can greatly improve the devolatilization performance of the equipment. In view of this, the fluid volume function method in computational fluid dynamics is used to simulate the film forming performance and surface renewal performance in high viscosity zone of disk reactor. In the disk window area, the liquid film thickness becomes thinner and the surface update frequency becomes faster, indicating that the disk window has a positive effect. The devolatilization performance of five new disk structures under different operating conditions is compared and analyzed. It was found that the influence of liquid level height on film area was greater than that of viscosity and rotation speed, the porous sector disk has excellent surface renewal performance and the baffle can achieve better mass transfer efficiency at a distance of 45–60 mm from the disk.

Insight into the thermocapillary radiative flow of hybrid nanoliquid film over an infinite rotating disk with entropy generation and heat source

Research into hybrid nanofluid flow over a disk surface is growing due to numerous processes in marine or gas turbines, rotating disk reactors for biofuels generation, cooling of spinning equipment components and other industrial applications. The purpose of this research study is to examine the entropy generation for the transient thermocapillary flow of hybrid nanoliquid thin films across a disk surface with different shapes of nanoparticles. To analyze the nanomaterial, the Tiwari–Das hybrid nanofluid flow model is established, and in doing so, Prandtl’s boundary layer theory is incorporated into this model. The energy equation considers the impacts of thermal radiation, two different kinds of heat sources — namely an exponentially space-dependent heat source and a linear thermal heat source — and viscous dissipation. The nonlinear partial differential equations, which explain the flow processes, are transformed into the nondimensional ordinary differential equations (ODEs). Once the ODEs have been constructed, they are next solved using the bvp4c technique. In addition, the surface drag force and the rate of heat transfer are both evaluated as functions of the shape factor of the nanoparticles that are disseminated in the base fluid. The influence of significant parameters on the flow fields is depicted graphically, and adequate physical explanations are provided for each representation. One of the important findings of this study indicates that the largest amount of heat transfer can be accomplished at the disk surface by employing nanoparticles with blade shape, while this physical quantity is the least when nanoparticles with spherical shapes are used. The temperature profile grows as the thermal and exponential heat sources increase. Entropy generation improves with the increase in either the magnetic parameter or the Brinkman number.

Numerical Simulation of a Simplified Reaction Model for the Growth of Graphene via Chemical Vapor Deposition in Vertical Rotating Disk Reactor

The process of graphene growth by CVD involves a series of complex gas-phase surface chemical reactions, which generally go through three processes, including gas phase decomposition, surface chemical reaction, and gas phase diffusion. The complexity of the CVD process for growing graphene is that it involves not only chemical reactions but also mass, momentum, and energy transfer. To solve these problems, the method of numerical simulation combined with the reactor structure optimization model provides a good tool for industrial production and theoretical research to explore the influencing factors of the CVD growth of graphene. The objective of this study was to establish a simplified reaction model for the growth of graphene by chemical vapor deposition(CVD) in a vertical rotating disk reactor (VRD). From a macroscopic modeling perspective, computational fluid dynamics (CFD) was used to investigate the conditions for the growth of graphene by chemical vapor deposition in a high-speed rotating vertical disk reactor on a copper substrate surface at atmospheric pressure (101,325 Pa). The effects of gas temperature, air inlet velocity, base rotation speed, and material ratio on the surface deposition rate of graphene in a VRD reactor were studied, and the technological conditions for the preparation of graphene via the CVD method in a VRD reactor based on a special structure were explored. Compared with existing models, the numerical results showed the following: the ideal growth conditions of graphene prepared using a CVD method in a VRD reactor involve a growth temperature of 1310 K, an intake speed of 470 mL/min, a base speed of 300 rpm, and an H2 flow rate of 75 sccm; thus, more uniform graphene with a better surface density and higher quality can be obtained. The effect of the carbon surface deposition rate on the growth behavior of graphene was studied using molecular dynamics (MD) from a microscopic perspective. The simulation showed that the graphene surface deposition rate could control the nucleation density of graphene. The combination of macro- and microsimulation methods was used to provide a theoretical reference for the production of graphene.

Experimental characterization and mixing modeling of a horizontally rotating disc reactor

Mixing is important in many chemical and biochemical processes to ensure uniform conditions throughout the process volume. A complex interaction arises for heterogeneous systems sensitive to the stress induced by mechanical mixing devices. This work introduces the Rotating Disc Reactor consisting of a horizontally rotating cylinder of a small width and partial filling, potentially allowing low-shear mixing. A colorimetric approach was implemented to study the mixing behavior. An increase in rotational speed resulted in a maximum reduction in mixing time by a factor of 7.5, while a higher filling level increased the mixing time by 20%. Also, doubling the reactor diameter doubled the mixing time at the same circumferential speed, and quadrupling the reactor width prolonged the mixing process similarly. Finally, a model is proposed to describe the dependencies of the dimensionless mixing number with a set of dimensionless groups.

Chemical reaction-mass transport model of Ga2O3 grown by TEGa in MOCVD and an intelligent system

Gallium oxide (Ga2O3) is rationally expected to have a wide range of applications prospects in power electronics, solar-blind UV detectors, gas detectors, and other fields. Metal-organic chemical vapor deposition (MOCVD) is a key technology for achieving high-quality and large-scale film growth, but with complex fluid fields, temperature fields, component distribution, and chemical reaction processes, the process is akin to a black box. In this study, the computational fluid dynamics (CFD) approach and a complete reaction mechanism were used to model the chemical reaction and mass transport for gallium oxide film growth based on a vertical rotating disc reactor (RDR) MOCVD system. The effect of temperature on film growth was explored and analyzed. It was found that the growth temperature can be divided into four regions, respectively controlled by thermal flow field, reaction rate, component transport, and parasitic reaction, and there is a competitive relationship between them. In the component transport region, the influence of different process parameters such as pressure, flow rate, and rotational speed on the growth was investigated. The regulation of film uniformity is achieved by the coupled regulation of 5 pairs of MO source inlets and multiple process parameters. Combined with artificial intelligence techniques, an intelligent system for realizing flow field visualization, growth result prediction, process parameter optimization, and abnormal result tracking was proposed for the first time. It can provide systematic guidance for film growth.

Recent Developments of Light-Harvesting Excitation, Macroscope Transfer and Multi-Stage Utilization of Photogenerated Electrons in Rotating Disk Photocatalytic Reactor

The rotating disk photocatalytic reactor is a kind of photocatalytic wastewater treatment technique with a high application potential, but the light energy utilization rate and photo quantum efficiency still need to be improved. Taking photogenerated electrons as the starting point, the following contents are reviewed in this work: (1) Light-harvesting excitation of photogenerated electrons. Based on the rotating disk thin solution film photocatalytic reactor, the photoanodes with light capture structures are reviewed from the macro perspective, and the research progress of light capture structure catalysts based on BiOCl is also reviewed from the micro perspective. (2) Macroscope transfer of photogenerated electrons. The research progress of photo fuel cell based on rotating disk reactors is reviewed. The system can effectively convert the chemical energy in organic pollutants into electrical energy through the macroscopic transfer of photogenerated electrons. (3) Multi-level utilization of photogenerated electrons. The photogenerated electrons transferred to the cathode can also generate H2O2 with oxygen or H2 with H+, and the reduction products can also be further utilized to deeply mineralize organic pollutants or reduce the nitrate in water. This short review will provide theoretical guidance for the further application of photocatalytic techniques in wastewater treatment.

Hydromagnetic flow of magnetite–water nanofluid utilizing adapted Buongiorno model

The hydromagnetic flow of magnetite–water nanofluid due to a rotating stretchable disk has been numerically assessed. The nanofluid flow has been modeled utilizing the adapted Buongiorno model that considers the volume fraction-dependent effective nanofluid properties and the major slip mechanisms. In addition, experimentally gleaned functions of effective dynamic viscosity and effective thermal conductivity are deployed. The modeled equations are transformed into a first-order ODEs scheme employing Von Kármán’s similarity conversions and then resolved via the Runge–Kutta algorithm through the shooting technique. The impact of pertinent terms over the physical quantities, nanoliquid temperature and nanoliquid concentration is explained with the support of graphs. Results show that rising volume fraction of magnetite nanoparticles (NPs) and magnetic field term enhance the drag force. Mass transport rate is demoted with augmenting values of magnetic field parameter whereas is promoted with increase in Schmidt number. Further, it is detected that the changes in stretching strength parameter are directly proportional to Nusselt number and inversely proportional to the thermal field. The findings of this numerical analysis have applications in spin coating, rotating disk reactors, storage devices for computers, food processing, and rotating heat exchangers.

Analysis of Von Kármán Swirling Flows Due to a Porous Rotating Disk Electrode

The study of Von Kármán swirling flow is a subject of active interest due to its applications in a wide range of fields, including biofuel manufacturing, rotating heat exchangers, rotating disc reactors, liquid metal pumping engines, food processing, electric power generating systems, designs of multi-pore distributors, and many others. This paper focusses on investigating Von Kármán swirling flows of viscous incompressible fluid due to a rotating disk electrode. The model is based on a system of four coupled second-order non-linear differential equations. The purpose of the present communication is to derive analytical expressions of velocity components by solving the non-linear equations using the homotopy analysis method. Combined effects of the slip λ and porosity γ parameters are studied in detail. If either parameter is increased, all velocity components are reduced, as both have the same effect on the mean velocity profiles. The porosity parameter γ increases the moment coefficient at the disk surface, which monotonically decreases with the slip parameter λ. The analytical results are also compared with numerical solutions, which are in satisfactory agreement. Furthermore, the effects of porosity and slip parameters on velocity profiles are discussed.

Insight on the dynamics of hydromagnetic stagnation‐point flow of magnetite‐water nanofluid due to a rotating stretchable disk: A two‐phase modified Buongiorno modeling and simulation

AbstractThe hydromagnetic stagnation‐point flow of magnetite‐water nanofluid due to a rotating stretchable disk has been numerically accessed. The nanofluid flow has been modeled by employing the two‐phase modified Buongiorno model that incorporates the volume fraction dependent effective nanofluid properties, Brownian motion, and thermophoresis effects. Von Kármán's similarity transformations are utilized in transmuting the mathematically modeled equations into a system of first‐order ODEs which are then resolved numerically using the bvp4c numerical scheme. The consequence of influential parameters on the flow profiles and the physical quantities has been presented through graphs and tables. Engineering quantities like moment coefficient and pumping efficiency of the disk are also elucidated in this research work. Results show that an augmentation in the Hartmann number descends the velocity profiles and ascends the nanofluid temperature profile. Further, a drop in the drag coefficient and a rise in the heat transfer rate are noted with an increment in the velocity ratio parameter. The tidings of this numerical simulation have applications in spin coating, rotating heat exchangers, and rotating disk reactors.

Highly efficient azo dye degradation in a photocatalytic rotating disc reactor with deposited l-histidine-TiO2-CdS

In the past few years, the quest for visible light active TiO2-based photocatalysts has been a hotly debated research topic in both scientific and practical fields. Attempting to meet the same purpose, in this study, a visible-driven nanocomposite, l-Histidine (2 wt%)-TiO2-CdS (7:1) nanocomposite, was dip-coated on the glass disc (rough vs. smooth) after the optimum composition was identified by varying the l-Histidine and CdS quantities. The prepared nanoparticles and coated catalyst on the disc were characterized by XRD, FT-IR, X-ray (FE-SEM/EDX), DRS, PL analyses in terms of their structural and optical properties as well as morphology. The coated photocatalyst was tested for photocatalytic degradation of direct red 16 (DR16) as an azo dye. The photodegradation process variables, including disc rotation speed, light intensity, irradiation time, and type of disc (smooth vs. rough glass disc)) were also modeled and optimized by central composite design (CCD). At the optimum conditions obtained, the effects of reaction time, pH, DR16 concentration, and aeration were investigated. After 3 h of using the rough disc (disc II) at a disc rotation speed of 100 rpm as well as a light intensity of 13 lumens per m2, DR16 was completely degraded. The pH and DR16 concentration seemed to have the reverse impact on the photodegradation process, whereas aeration had such a positive effect. By analyzing the effects of various scavengers, the contribution of reactive species in the photodegradation process was thoroughly investigated. Furthermore, the reusability results indicate no significant change in the photodegradation efficiency after four cycles.

Numerical investigation of twin-liquid film on spoked rotating disk reactor with highly viscous fluid

• Twin-liquid film flow has been observed on a spoked rotating disk reactor. • Interplay between the confined free film and wall-bounded film leads to mass transfer intensification. • The circumferential length of the opening window should be accommodated to fluid viscosity. Spoked rotating disk reactor is a common gas–liquid mass transfer equipment for highly viscous fluids. The hydrodynamics of the twin-liquid film on the disk is numerically investigated. The simulated film thickness, which agrees well with the experimental results, shows that film flow patterns shift at different rotational speeds. The alternation between the windows and spokes brings diverse film flow pattern, i.e. , twin-liquid film, where a confined free film and a wall-bounded film coexist and interplay. The twin-liquid film results in 70% thinning of the film thickness and 30% increase in the surface renewal frequency compared to the wall-bounded film. Based on the trajectory of the tracking particles, intense velocity fluctuations within the twin-liquid film can be observed. Given the pressure gradient within the opening window increasing exponentially with fluid viscosity, we suggest that the circumferential length of the open window be proportional to fluid viscosity. The results demonstrate good adaptability of the optimization strategy, which can guide the scaling-up of the spoked rotating disk reactors for highly viscous fluids.

An Evaluation of Metronidazole Degradation in a Plasma-Assisted Rotating Disk Reactor Coupled with TiO2 in Aqueous Solution

Pollution involving pharmaceutical components in bodies of water is an increasingly serious environmental issue. Plasma discharge for the degradation of antibiotics is an emerging technology that may be relevant toward addressing this issue. In this work, a plasma-assisted rotating disk reactor (plasma-RDR) and a photocatalyst—namely, titanium dioxide (TiO 2 )—were coupled for the treatment of metronidazole (MNZ). Discharge uniformity was improved by the use of a rotating electrode in the plasma-RDR, which contributed to the utilization of ultraviolet (UV) light radiation in the presence of TiO 2 . The experimental results showed that the degradation efficiency of MNZ and the concentration of generated hydroxyl radicals respectively increased by 41% and 2.954 mg∙L −1 as the rotational speed increased from 0 to 500 r∙min −1 . The synergistic effect of plasma-RDR plus TiO 2 on the generation of hydroxyl radicals was evaluated. Major intermediate products were identified using three-dimensional (3D) excitation emission fluorescence matrices (EEFMs) and liquid chromatography–mass spectrometry (LC-MS), and a possible degradation pathway is proposed herein. This plasma-catalytic process has bright prospects in the field of antibiotics degradation.

Acid retardation for deeper stimulation—Revisiting the chemistry and evaluation methods

AbstractAcid fracturing treatment in upstream oil and gas production is done to extend the connectivity of the wellbore deep into the reservoir. This is achieved through a dissolution process using acid in conjunction with hydraulic fracturing. A key to success is to impart favourable reaction kinetics between the acid and rock matrix. If the reaction proceeds too rapidly, it results in large voids in the near‐wellbore area but insufficient dissolution in the reservoir. Hydrochloric acid (HCl) is ubiquitous in the petroleum industry for acidizing applications due to its high dissolving capacity towards carbonate minerals, soluble reaction products, and low cost. Its corrosive nature coupled with rapid reaction kinetics have forced the industry to search for mechanisms to address these limitations. The concepts for slowing down reaction rate centre around (1) reducing mass transfer of hydrogen ions, H+; (2) limiting H+ ion dissociation; and (3) altering the wetting property of the rock surface. Reaction kinetics data is critical to guiding the selection of the suitable acid formulations for acid fracturing process. They are commonly measured in the lab using instruments such as a rotating disk reactor, flow cells, and diffusion cell. Though routinely applied, these experimental methods, including their setups and procedures, are rarely questioned. The experimental artefacts can lead to wrong conclusions. Deeper understanding of the fundamental assumptions behind the apparatus design and test procedures is critical. This paper discusses the chemistries employed in acid retardation, and more importantly the attention needed when extending the experimental data to field treatment.

Performance evaluation of novel Mica@reduced graphene oxide fixed rotating disk reactor in treatment of anaerobically reduced textile dyeing wastewater containing aromatic amines

AbstractBACKGROUNDAnaerobically reduced textile dyeing wastewater containing aromatic amines can cause serious environmental problems as a consequence of their toxicity.RESULTSThe performance of a novel design, laboratory‐scale mica@reduced graphene oxide (rGO) reactor fixed on three rotating disks was evaluated for the removal of anaerobically reduced textile dyeing wastewater containing aromatic amines. Fourier‐transform infrared and UV–visible spectroscopy analyses of wastewater after anaerobic treatment revealed that it contained high aromatic compound concentrations. Scanning electron microscope images confirmed that the rGO nanosheets were deposited on the mica surface by the spin‐coating method aromatic amines adsorbent. The effects of wastewater initial chemical oxygen demand (COD) concentration (100, 500 and 1500 mg L–1), pH (5, 7 and 9) and processing temperature (293, 303 and 313 K) on the aromatic compounds and COD removal using the designed reactor were investigated. The results indicated that aromatic molecule adsorption occurred faster with higher wastewater COD concentration. Also, increase in pH improved the mica@rGO adsorption. Likewise, the increase in temperature caused swelling in the stacked graphene layers, resulting in new surfaces for adsorption, leading to an increase in reactor efficiency. The experimental results indicated that the adsorption process fitted well with the Langmuir isotherm model and pseudo‐second‐order reaction kinetics. The thermodynamic study revealed that the adsorption was spontaneous.CONCLUSIONThe improvement in the removal of aromatic molecules by Mica@rGO indicates that the novel designed reactor has a great potential for the treatment of textile wastewater. © 2021 Society of Chemical Industry (SCI).

Plasma-Assisted Rotating Disk Reactor toward Disinfection of Aquatic Microorganisms

Plasma discharge in contact with water is a promising technology for disinfection. Developing efficient gas–liquid nonthermal plasma reactors for disinfection is very urgent. In this work, a plasma...

CO2 absorption performance in a rotating disk reactor using DBU-glycerol as solvent

Abstract Gas–liquid mass transfer of rotating disk reactor was studied in CO2 absorption using 1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)-glycerol solution as solvent. Effects of the rotating disk structure and various operation parameters on the CO2 absorption rate and CO2 removal efficiency were investigated. The rotating disk with optimal holes is conducive to mass transfer of CO2 and the formation of thin liquid film at the opening increases the gas–liquid contact area. With the increase of rotating speed, the liquid flow pattern on the rotating disk surface changes from thin film flow to separated streams and creates extra liquid lines attached to the rim of the disk, which leads to a very complicated change on the CO2 absorption rate and CO2 removal efficiency. The overall gas-phase mass transfer coefficient increases 138% as the rotating speed increasing from 250 to 1400 r·min−1. Increasing temperature from 298 to 338 K can enhance the CO2 absorption rate due to lowering the viscosity of the solvent. The rate-determined step for the absorption is focused on the gas side. The rotating disk reactor can effectively enhance the absorption of CO2 with viscous DBU-glycerol solvents.

A novel plasma-assisted rotating disk reactor: Enhancement of degradation efficiency of rhodamine B

Plasma-based process intensification is considered as a promising technology in advanced oxidation processes (AOPs) for the wastewater treatment. In this work, we have developed a novel plasma-assisted rotating disk reactor (plasma-RDR). The rotating disk was used as ground electrode to improve the discharge uniformity, and also as an internal to enhance the mass transfer efficiency. Experimental results show that the degradation efficiency of Rhodamine B (RhB) in the plasma-RDR increased by 60% within 30 min when the rotational speed varied from 0 to 500 rpm. A discussion for the enhancement of degradation efficiency in the plasma-RDR was presented. Effects of peak voltage, electrode gap, and other operating conditions on the degradation efficiency of RhB in the plasma-RDR were investigated. Major intermediates of RhB degradation after the plasma treatment were also analyzed.

Design of a rotating disk reactor to assess the colonization of biofilms by free-living amoebae under high shear rates

The present study was aimed at designing and optimizing a rotating disk reactor simulating high hydrodynamic shear rates (γ), which are representative of cooling circuits. The characteristics of the hydrodynamic conditions in the reactor and the complex approach used to engineer it are described. A 60 l tank was filled with freshwater containing free-living amoebae (FLA) and bacteria. Adhesion of the bacteria and formation of a biofilm on the stainless steel coupons were observed. FLA were able to establish in these biofilms under γ as high as 85,000 s−1. Several physical mechanisms (convection, diffusion, sedimentation) could explain the accumulation of amoeboid cells on surfaces, but further research is required to fully understand and model the fine mechanisms governing such transport under γ similar to those encountered in the industrial environment. This technological advance may enable research into these topics.

Deposition-Free Process on Reactor Sidewalls during Si Deposition in Vertical Rotating Disk Reactors

An effective deposition-free process that can suppress extraneous deposition on reactor sidewalls during Si deposition from a SiHCl3-H2 gas mixture in a vertical rotating disk (VRD) reactor is proposed. The experimental results indicated that etching (or cleaning) could remove deposition on and around a susceptor, whereas the deposition remained on the sidewalls because the temperature of the sidewalls was estimated to be lower than that of the susceptor. In addition, the Si deposition rate decreased when hydrogen chloride (HCl) gas was added to the inlet carrier hydrogen (H2) gas, and became zero when the inlet concentrations of SiHCl3 and HCl gases were 3 and 7% in the H2 carrier gas, respectively. Based on these experimental results, a numerical analysis was conducted to evaluate a suitable way to provide HCl gas into the VRD reactor for the purpose of suppressing extraneous deposition on the sidewalls. It was numerically predicted that providing HCl gas along the side wall was effective and controllable by adjustment of the concentration and flow rate of additive HCl gas. An experiment was conducted to verify the proposed measure in a commercial VRD reactor and the results showed that it enabled suppression of extraneous deposition during the Si deposition process in a VRD reactor.