Presence Of Baffles Research Articles

Exploring pharmaceutical powder behavior in commercial-scale bin blending: A DEM simulation study

Bin blending is one of the main steps in pharmaceutical production processes. Commercial-scale production of expensive products typically does not allow to perform a large number of experiments in order to optimize the process. Alternatively, Discrete Element Method (DEM) simulations can be used to evaluate the powder behavior (flow and blending pattern) during blending, identify the risks (e.g., segregation), and provide solutions to mitigate them. In this work, DEM simulations are used to investigate the blending of two granulated powders in commercial-scale cone and cylindrical (hoop) blenders. The DEM contact model parameters were calibrated based on the experimental compression and ring shear tests for both granulated powders to mimic the bulk powder behavior in the simulations. The model's output was compared to the experiments in one of the blending cases. The blending efficiency in the cone blenders was evaluated considering the fill levels, the presence of baffles, the rotating directions, the filling order, and the bin sizes. Furthermore, for the hoop blenders, the effects of blender's angle, rotation speed, and filling order were addressed. The main findings of the work were that, in cone blenders, the blending can be improved by introducing baffles and changing in the rotational direction frequently. In hoop blenders, blending can be improved by increasing the inclination angle from the horizontal plane and the rotational speed.

Magnetic field impact on free convection of a nanofluid in a cavity with corrugated walls and having V-shaped baffles

In this study, an investigation of heat transfer by free convection in a wavy-walled cavity loaded with Al2O3–water nanofluid and subjected to a magnetic field was developed. In lower wall of this cavity baffles are installed. The different conservation equations were solved via Ansys-Fluent software by applying the finite volume technique and the buoyancy forces were expressed by Boussinesq approximation. This investigation gives explanations on the impact of the different factors on heat exchange and nanofluid movement in the chosen geometry, namely, Rayleigh and Hartmann numbers, volume fraction, and presence of baffles which is considered the novelty of this work. Results found illustrate that heat exchange is enhanced by intensification of Rayleigh number and addition of nanoparticles, due to development of a significant temperature gradient and the improved characteristics of nanofluids while the growth of Hartmann number reduces heat exchange owing to the magnetic field action on free convection. Depending on the configuration studied, the installation of the baffles can sometimes localizes the flow in an area of the enclosure and reduces heat transmission which is the case of this study. Finally, correlations were proposed for Nusselt number to get an idea on heat exchange rate and which are rarely given in this type of studies. These results can help in the design of certain energy systems.

Intensification of the rate of heat and mass transfer at the wall of a stirred tank reactor by integrating a helical coil turbulence promoter with the tank wall

ABSTRACT The influence of a helical coil turbulence promoter on liquid-solid mass transfer rates in a stirred tank was investigated using a technique that involved measuring the rate of diffusion-controlled copper dissolution in acidified dichromate. The study examined the effects of helical coil tube diameter (d), helical coil pitch (p), impeller rotation speed, impeller geometry (axial and radial), the presence of baffles, and solution physical properties. The presence of the helical coil near the reactor wall significantly enhanced mass transfer rates, with a factor ranging from 1.01 to 2.48. This improvement was accompanied by a corresponding increase in the volumetric mass transfer coefficient (kA), ranging from 2.68 to 4.55, depending on operating conditions. Further analysis revealed that the average mass transfer coefficient increased with decreasing coil tube diameter, while coil pitch had a minimal impact. Additionally, radial flow turbines demonstrated superior mass transfer performance compared to axial flow turbines. The presence of baffles also promoted higher mass transfer rates compared to unbaffled reactors. The experimental data were successfully correlated using dimensionless correlations, emphasizing the significance of these correlations in scaleup and design optimization of catalytic stirred tank reactors with efficient cooling systems.

CFD simulations of supplemental cooling techniques in cross-ventilated dairy buildings and associated greenhouse gas emissions

Dairy ventilation studies typically focus on reducing heat stress. Dairy buildings are often constructed with ventilation systems that exceed recommendations without prioritizing energy use. Given the rising production costs that dairy farmers face, it is becoming increasingly important to implement energy-saving technologies that can help reduce operating expenses. In this study, we tested whether ventilation rates of dairy buildings could be lowered when the existing cross-ventilation system was supplemented with a ground source heat pump for conductive or convective cooling. Computational fluid dynamics (CFD) models were validated by comparing measurements taken in a cross-ventilated building to the simulated data. It was found that the presence of baffles helped cool the barn, and the difference between the inlet and outlet barn temperatures was less than 2 °C (0.86 ± 0.08 °C at 0.5 m height), as recommended. However, there were still warm spots (T > 30 °C) within the stalls. When conductive cooling was implemented, the air velocity could be lowered from 1.03 ± 0.34 to 0.71 ± 0.29 m/s, resulting in reduced energy consumption and associated greenhouse gas emissions (14.7–25.5 %) while achieving the same temperature profile. With convective cooling, air velocity could be lowered to 0.69 ± 0.18 m/s, leading to a 17.0–27.7 % reduction in greenhouse gas emissions. Moreover, it decreased the average temperature at the 0.45–0.55 m (cow sitting height) from 29.3 ± 0.80 °C to 28.1 ± 0.15 °C. Given the projected rise in the social cost of carbon, supplementing cross ventilation with convective cooling has the potential to have economic and environmental benefits and lower the number of warm spots observed inside the building. However, a more detailed cost analysis is needed before making any recommendations.

The performance of rotating membrane emulsification in the presence of baffles: Insights from flux experiments, microstructural analysis, and positron emission particle tracking

Rotating Membrane Emulsification (RME) is a bottom-up emulsification technique developed to circumvent the significant energy requirements of conventional methods; however, its implementation has been hindered by low emulsion throughputs. This work presents a novel baffled-RME setup and investigates the potential improvement to emulsion throughput and droplet microstructure, whilst employing both surface-active and Pickering particle emulsifiers to assess whether any advantages are emulsifier-specific. Overall, baffle addition improves emulsion throughputs, however the droplet microstructure was positively influenced only when using surfactant-based emulsifiers. Positron Emission Particle Tracking (PEPT) was utilised to demonstrate that these advantages result from improved hydrodynamic conditions instigated by the break-up of streamlines, inducing higher turbulence near the membrane surface, and by increasing the transmembrane pressure drop and drag force through flow restrictions. Overall, by detailing the first baffled-RME setup and first application PEPT analysis to such equipment, this work lays the foundation for further optimisation of bottom-up emulsification approaches.

Numerical investigation on intensified mixing performance with modified dual impeller

Process intensification is important for achieving efficient fluid mixing. In this study, the process intensification mechanism of mixing was investigated based on the evolution of sub-steady flow pattern. The results showed that the modified dual impeller (Mod-DI) could eliminate the isolation zone and symmetry of the flow pattern, which always appears in the traditional dual impeller (Trad-DI) system. Furthermore, the mixing time (tm) and dynamic equilibrium time (tde) of the Mod-DI system were significantly shorter than those of the Trad-DI system, which could be attributed to the enhancement of fluid flow fluctuations caused by the loss of stability of sub-steady flow field. In the presence of baffles, tm and tde could be further reduced. The shortening of time was at the expense of increasing power consumption. Overall, the intensification mechanism of the Mod-DI is mainly since the formation of sub-steady flow field, which enhances the instability of the fluid flow.

Numerical investigation of baffle shape effects on performance and mass transfer of proton exchange membrane fuel cell

Flow channels with baffles can enhance the transport of reactants and improve the performance of proton exchange membrane fuel cell (PEMFC). In this study, five different structures of flow channels with baffles are proposed, and the mass transfer and cell performance of PEMFC with different baffled channels are compared by CFD method. The results show that the PEMFC with a cutting cylindrical baffle has the best performance with an output current density of 1.82 A/m2 when the voltage is 0.4 V. Baffle design can promote reaction gas transmission while also increasing reaction gas concentration in the channel. Due to the circular arc surface design of the cylindrical section, the mass transfer enhancement effect of cutting baffles is better. When the fluid passes through the baffles, the velocity magnitude also changes abruptly due to the disturbance effect, and the more effective convection brought about by the reactants being pushed into the catalytic layer can enhance the mass transfer in the PEMFC and obtain better performance. The presence of baffles will increase the accumulation of water, the smaller the cross-sectional area, the better the water removal effect. Vortex generation will result in large parasitic power, which is detrimental to the performance of the PEMFC.

SIMULASI KESTABILAN PROTOTYPE UAV-SPRAYER BERBASIS QUADCOPTER TERHADAP PENAMBAHAN SEKAT PADA PENAMPUNG CAIRAN

The use of UAVs has begun to penetrate the world of agriculture. One of the functions of UAVs in agriculture is to spray pesticides. The pesticides used are liquid so that when the UAV is airborne and maneuvering, the fluid experiences fluid motion or sloshing. Sloshing that occurs can cause the balance of the UAV to be disturbed. To overcome this, a bulkhead or baffle is needed in the reservoir in order to reduce fluid movement. In the case of the research studied, the simulation of sloshing in the reservoir with the presence of baffles and without the presence of baffles. This research uses different reservoir variations and different water levels, namely 55 mm, 35 mm and 15 mm. Simulations are carried out during cruising and maneuvering flights at a speed of 2 m/s. The container modeling uses the Catia V5R20 software and the simulation uses the Ansys 14.5 software. The simulation results show that the effect of baffle placement is more visible if the baffle is placed in the xy plane, while for the baffle placement in the yz plane, the force caused by sloshing is greater. In spraying the UAV-Sprayer will more often fly forward (cruise), while for maneuvers (right or left) it is only done occasionally/not too often. So that giving baffles is more effective in the xy plane because it can reduce sloshing better than the baffles in the yz plane.

Effect of fluid hydrodynamic situations on enzymatic hydrolysis of mixed microalgae: Experimental study and simulation

The enzymatic hydrolysis of microalgae has already been studied for bioethanol production. However, the enzymatic hydrolysis of microalgae under various fluid hydrodynamic conditions has not been simulated yet. Accordingly, the present study investigated the effect of various stirrer speed values, impeller types, and the presence of baffles on glucose extraction from the mixed microalgae using cellulase. The Michaelis-Menten kinetic constants of enzymatic hydrolysis were calculated in the AQUASIM and were used for simulation in COMSOL. The simulated values agreed with the experimental results and revealed that the low stirring speed reduced glucose extraction through undesirable enzyme distribution and the formation of regions with a high concentration of hydrolysis products to inhibit the enzyme's operation. The higher uniformity of glucose concentration at higher stirring speeds compared to lower stirring speeds ensured the higher efficiency of the mixing process in this reactor. The study findings suggested that a sufficient understanding of the mixing effects in the enzymatic hydrolysis could improve the economic feasibility of the process. Furthermore, compared to the unbaffled reactor, the proper mixing in the baffled reactor increased the enzymatic hydrolysis rate. It was found that altering the impeller type leads to a negligible change in the enzymatic hydrolysis rate.

Effect of Baffles Position on Thermo-Hydraulic Efficiency of a Solar Air Heater

Providing artificial irregularity in the form of baffles on the bottom plate of a solar air heater improves the thermal performance of the heater, whereas it reduces the hydraulic efficiency due to friction losses. To optimize the thermo-hydraulic performance of a rectangular duct solar air heater, a thermo-hydraulic performance factor (THPF), dependent on shape, position and size of baffles, is considered in this study. The performance of the heater in various configurations related to the position of the baffles was evaluated considering Renormalization group k-£ model to simulate the fully turbulent flow for a forced convection condition. At a constant value of heat flux of 1000 W/m2 on the absorber plate and a fixed value of Reynolds number as 2350, pitch between the baffles was varied from 15mm to 75mm. Further, the distance of 1st row of baffles from the inlet was varied from 200mm to 500mm and the optimum configuration was figured out. For pitch value of 60mm between the baffles and the distance of 1st row of baffles as 200mm from the inlet, the highest value of THPF was obtained as 0.9339. The fluid behavior in presence of baffles was analyzed together with its influence on the thermo-hydraulics parameters.

Integration of sub- meter scale lithological heterogeneity in reservoir models for an improved quantification of CO2 trapping capacities

Sub-meter scale lithological heterogeneity in the form of sedimentary structures such as cross, planar and massive beddings is known to enhance carbon mineral trapping. However, this understanding is largely qualitative. Quantitative estimates of trapping capacities at this scale are limited by the availability of high-resolution field data. Additionally, such heterogeneity is typically not accounted for in conventional reservoir models due to computational restriction posed by the grid size resolution. As a result, the impact of sub-meter scale lithological heterogeneity on carbon trapping capacities is typically not accounted for in dynamic flow and reactive transport simulations at the reservoir scale. The present study aims to quantify the impact of intraformational baffles on carbon mineralization for a range of rock types. A series of 2-D multiphase reactive transport simulations were set-up to model the geochemical processes occurring at the interface of a baffle and a reservoir rock for a period of 1000 years. The study shows that the presence of baffles with certain rock properties within the reservoir rock can enhance or reduce carbon mineral trapping capacity relative to homogeneous reservoir rocks depending on clay and carbonate mineral content in baffles. Further, a new workflow is developed to build a 2D high-resolution reservoir model of the Paaratte Formation, Otway Basin while overcoming the technical challenges associated with sub-meter scale discretization of geological models.

Divertor closure effects on the TCV boundary plasma

The Tokamak à Configuration Variable (TCV) has recently been equipped with gas baffles to increase its divertor closure for a broad range of divertor magnetic geometries. First experimental results reported in Reimerdes et al. (2021) demonstrated compatibility with a broad range of divertor magnetic geometries and confirmed the main design constraints of the baffles, in particular an increased divertor neutral pressure. The present article presents a more in-depths analysis and extended experiments of this first baffle assessment on the TCV boundary plasma. It is shown that the divertor neutral pressure increased following the installation of the baffles, as predicted by SOLPS-ITER and SolEdge2D-EIRENE simulations. Varying the divertor closure by changing the position of the plasma showed that the plasma equilibrium designed to assess the baffle effect was not far from the optimal trade-off between plasma plugging and recycling on the baffles. The baffles facilitate access to a partially detached regime in both L- and H-modes. In L-Mode, with the ion ∇B-drift directed from the X-Point to the plasma core, a reduction of the line-averaged density detachment threshold by approximately 20% is observed at the outer target, while inner strike point detachment is only achieved in the presence of baffles. Multispectral imaging shows that the CIII front moves from the outer target towards the X-Point at a lower line-averaged plasma density, indicating a colder outer leg. In H-mode, the CIII front is generally located near the X-Point between the ELMs, while without baffles, N2-seeding is required to move the front up to that location.

Flow modelling to quantify structural control on CO 2 migration and containment, CCS South West Hub, Australia

In order to reduce uncertainties around CO 2 containment for the South West Hub CCS site (Western Australia), conceptual fault hydrodynamic models were defined and numerical simulations were carried out. These simulations model worst-case scenarios with a plume reaching a main compartment-bounding fault near the proposed injection depth and at the faulted interface between the primary and secondary containment interval. The conceptual models incorporate host-rock and fault properties accounting for fault-zone lithology, cementation and cataclastic processes but with no account made for geomechanical processes as the risk of reactivation is perceived as low. Flow simulations were performed to assess cross-fault and upfault migration in the case of plume–faults interaction. Results near the injection depth suggest that the main faults are likely to experience a significant reduction in transmissivity and impede CO 2 flow. This could promote the migration of CO 2 vertically or along the stratigraphic dip. Results near the interface between the primary and secondary containment intervals show that none of the main faults would critically control CO 2 flow nor would they act as primary leakage pathways. CO 2 flow is predicted to be primarily controlled by the sedimentological morphology. The presence of baffles in the secondary containment interval is expected to be associated with local CO 2 accumulations; additional permeability impacts introduced by faults are minor. Thematic collection: This article is part of the Geoscience for CO 2 storage collection available at: https://www.lyellcollection.org/cc/geoscience-for-co2-storage

Conditions and processes controlling carbon mineral trapping in intraformational baffles

Carbon mineral trapping is commonly believed to be insignificant relative to other trapping mechanisms, yet, the role of cm-scale intraformational baffles is rarely considered in reservoir scale assessments. The present study aims to reveal conditions governing carbon mineral trapping and its quantification for a range of rock compositions in intraformational baffles. A series of 2-D multiphase reactive transport simulations were set-up to model the geochemical processes occurring at the interface of a baffle and a reservoir rock for a period of 1000 years. The study shows that the presence of baffles with certain rock properties within the reservoir rock can enhance or reduce carbon mineral trapping capacity relative to homogeneous reservoir rocks depending on clay and carbonate mineral content in baffles. The analysis shows that the precipitation of secondary carbonates occurs at the interface of the two rock types. Furthermore, it was found that higher clay and lower carbonate content of the baffle contribute towards enhancing mineral trapping while the mineralogy of reservoir rock does not have an important influence. The results are further utilized to derive averaged mineral composition for the integration of fine scale processes in coarser scale simulations.

Mass transfer at the outer surface of a spiral tube heat exchanger in a stirred tank reactor and possible applications

Mass transfer at the external surface of a horizontal spiral tube exchanger placed at the bottom of a stirred tank was investigated by using the dissolution of copper in acidified dichromate technique under different considerations of (i) reactor configuration (i.e., presence of baffles, spiral tube distance from the tank bottom, spiral tube diameter and pitch, impeller geometry), (ii) acidified dichromate solution properties, and (iii) mixing intensity (i.e., impeller rotational speed). It is revealed that mass transfer increases with increasing mixing intensity, spiral tube pitch, and with the presence of baffles. The larger the spiral tube diameter, the lower the mass transport. The results, for spiral tube placed at the tank bottom, in case of axial- and radial-flow impellers were correlated by dimensionless correlations with an average deviation of 11% and 9%, respectively. Applications of the current results include (i) design of a spiral tube heat exchangers in agitated vessels, (ii) design of catalytic heat exchanger/reactor suitable for exothermic reactions involving heat-sensitive materials, and (iii) design of semi-continuous spiral tube membrane equipment suitable for processes such as dialysis and ultrafiltration.

The Effect of Using Baffles on the Rate of Mass Transfer of a Cylindrical Stirred Tank Reactor

Owing to the high mixing capacity, the stirred tank reactor is the key class of reactors in the chemical process industry and pharmaceutical industry. The mass transport nature of a batch stirred tank reactor with a fixed copper wall with a cylinder form was studied using copper dissolution in acidified dichromate which is controlled by diffusion. Variables analyzed included the speed of rotation of the impeller, the shape of the impeller and the physical specifications of the solution and the existence of baffles. The data were correlated for the conditions 3667.323 < Re < 34993.18 and 960 < Sc < 1364, for radial flow by the equation: Sh =0.3453 *Sc1/3*Re0.66 but for axial flow by the equation: Sh =0.5866 *Sc1/3*Re0.59. Through speed of rotation of the impeller increases,it allows the rate of mass transfer from the fixed bed to the solution to rise. The radial-flow turbine is more effective than the axial-flow turbine in increasing the rate of mass transfer. The usage of baffles plays a significant role in rising the rate of mass transfer. Using baffles; the correlation will be Sh =0.0769 *Sc1/3*Re0.84 for radial flow and Sh =0.1157 *Sc1/3*Re0.78 for axial flow. The purpose of this research is to estimate the rate of mass transport that can be required in corrosive reactions, and also to maximize the mass transfer rate that can be achieved in other processes, such as electroplating in presence of baffles.

CFD simulation of the aeration process and baffle influence in a full-scale commercial flat sheet module

The goal of the present paper is to investigate the aeration process and the enhanced effect of baffles in a full-scale commercial membrane bioreactor (MBR) system configured with a flat sheet (FS) membrane module. Through a computational fluid dynamics (CFD) simulation, two aerated FS membrane modules for full-scale applications with 26 membrane sheets were simulated. The numerical results indicate that the presence of baffles and the distances between the baffle and the outmost membrane sheet have a minor influence on the area-weighted shear stress for full-scale MBRs. In addition, bubble size and the bottom distance between the aerator and membrane bottom do not affect the average shear stress of full-scale FS membrane modules much. However, an increase in air flow rate has a significant effect on the area-weighted shear stress. A large FS membrane module is recommended, as it could achieve the same cleaning effect as the small one with a lower specific aeration demand for membranes.

Recovery of Copper from Industrial Waste Solutions by Cementation Using a Rotating Fixed Bed of Stacked Steel Screens

The performance of a rotating fixed bed reactor in recovering copper from industrial waste solutions by cementation is studied under various conditions. The rotating fixed bed is made of stacked woven steel screens to take advantage of two features of screens: the ability to present large area per unit volume and their ability to promote high turbulence. Variables studied are initial CuSO4 concentration, bed rotation speed, mesh number of the screens and bed thickness. The presence of baffles was found to increase the rate of cementation. The data were correlated by a dimensionless mass transfer correlation suitable for the design and operation of large scale cementation reactors.

Laminar cooling of shear thinning fluids in horizontal and baffled tubes: Effect of perforation in baffles

The vortex generators are well known by their great efficiency to improve the hydrothermal characteristics of heat exchangers. The presence of baffles has proved its major role in the enhancement of heat transfer rates, but with a greater pressure drop. In this paper, circular perforations are introduced in the baffle embedded in a tube heat exchanger (THE) in order to reduce the pressure drop. The working fluid has a complex non-Newtonian behavior (shear thinning) modeled by the Ostwald’s model. The influence of several geometrical and operating parameters on the flow fields and thermal characteristics of the heat exchanger are investigated. It concerns the presence of perforations in the baffle, the number of perforations (nb = 1, 2, 3 and 4), perforation diameter (d/D = 0.1, 0.26 and 0.4) and the Reynolds number (from 0.1 to 200). The predicted results revealed the advantage of perforated baffles in the reduction of pressure losses, also the thermal performance factor (TPF) at Reg = 200 for the tube heat exchanger with d/D = 0.4 is found to be higher by about 13.6% and 6.5% than those at d/D = 0.1 and 0.26, respectively. An improvement in TPF by about 7% was obtained with nb = 4 compared to the baffle with only one perforation (nb = 1), at d/D = 0.1, Reg = 200.

Parameters affecting LED photoreactor efficiency in a heterogeneous photo-Fenton process using iron mining residue as catalyst

In this article, a light-emitting diode (LED)-based photoreactor was designed and evaluated for degradation of the antibiotic sulfathiazole (STZ), using heterogeneous photo-Fenton process with an iron ore residue as catalyst. The effects of the type of magnetic stirrer bar, use of baffles, rotation speed, and type and intensity of irradiation source were evaluated. The results showed that the degradation of STZ was strongly influenced by rotation speed (1100 rpm) and that the use of an octagonal stirrer bar favoured high dispersion and greater contact of the catalyst with the reaction medium. Although the presence of baffles had little influence on STZ degradation, their use enabled good dispersion of the catalyst (due to axial flow) and eliminated the vortex formed at high stirring speeds. It was found that the iron mining residue could be activated by UV LEDs, visible light LEDs, and black light irradiation, with similar degradation efficiencies achieved. Using the LEDs, STZ concentrations below the detection limit were obtained after 40 min, with power consumption 38-fold (UV LEDs) and 22-fold (visible light LEDs) lower than required for black light irradiation. The results demonstrated the advantages of the use of LED devices as irradiation systems in heterogeneous photo-Fenton processes.