A computational fluid dynamics (CFD) modeling approach was developed to study the mixing of two immiscible liquids in NETmix reactors. A two‐dimensional two‐phase CFD model based on the Euler‐Euler ...approach with the volume‐of‐fluid (VOF) method was implemented in a reduced physical domain from the imposition of periodic boundary conditions. The fluids modeled were sunflower oil and water. The VOF modeling was validated by comparison with experimental results. CFD results predicted the actual flow regimes and overall flow patterns for each phase at three Reynolds numbers. The validation demonstrated the 2D CFD model to describe the physics of two‐phase flow in the NETmix reactors. This model can be applied to design studies for liquid‐liquid extraction or gas‐liquid reactors, where the operation flow regime is crucial.
A reduced laminar dynamic 2D computational fluid dynamics model with volume‐of‐fluid permits accurate simulation of two‐phase flow in a NETmix reactor. Experimental results validated the modeling. The oil stream was kept at low Reynolds number, thus viscosity was the dominant factor for equal phases flow rates. The simulations enable dynamic tracking of the liquid‐liquid flow for two flow regimes.
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•Nearly-closed two-step process for recovering Cu and Al from PCBs residue.•A first step, based on mild concentrated acid, allowed Cu and Ag extraction with high yield.•A second step, ...based on chelating ion exchanger, for Cu purification.•Recovery of 75% of Cu from the PCBs residue into a Cu solution with 99.0% purity.•Recovery of 85% of Al, as Al(OH)3, from the raffinate.
The large amount of Cu present in printed circuit boards (PCBs) residues, usually about ten times more than the Cu amount present in rich-content minerals, makes these residues an attractive secondary source of Cu. Thus, the main aim of this work was to develop a simple and nearly-closed two-step process to recover Cu from PCBs residues with high purity.
Firstly, a multi-element leaching solution, containing 78% of the total amount of Cu present in the residue together with other metals, was obtained using acidic (HNO3 2mol/L for 210′ at 50°C) conditions. In a second step, a bispicolylamine resin was used to recover Cu with high selectivity from the multi-element (59.0% Cu) leaching solution and a final Cu solution with high purity (99.0%) was obtained after eluting, with H2SO4 4mol/L, the Cu retained in the column.
Additionally, the amount of Al (85%) leached from the residue, present in the raffinate, was totally recovered as a solid of Al(OH)3.
•NETmix surpasses most state-of-the-art technology for mixing and heat transfer•NETmix shows high flow dynamics and interfacial area generation between two liquids•The onset of chaotic regime leads ...to an intense fluid renewal around the interfaces•Large potential for mass transfer applications between two immiscible liquid phases•The CFD model can be applied for design studies for liquid-liquid/gas-liquid flow
NETmix has been shown to be an efficient mixing technology for miscible fluids, promoting large heat and mass transfer rates. This work intends to assess NETmix for multiphase mixing, which is particularly relevant to evaluate the NETmix's ability to couple mixing and heat transfer. The first step is to build fundamental knowledge regarding two-phase flow in these devices. A 2D CFD two-phase model was implemented based on the Euler‑Euler approach with the Volume of Fluid (VOF) method using the NETmix Unit Block (NUB). The two phases are liquids with equal density and viscosity, enabling to study the impact of the interfacial tension and the contact angle on the flow dynamics and drop formation. Mass transfer was assessed from the flow shear at the interface of the two phases. The CFD model was experimentally validated using a water-cyclohexane system. The NETmix technology promotes high flow dynamics and large interfacial area generation between the two phases. The successive split and recombining of flow contribute to an intense fluid renewal around the two phases' interface, enhancing the mass transfer rate. NETmix shows potential for multiphase applications, particularly between two immiscible liquid phases, with a four-fold increase of the interfacial area of immiscible fluids.
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Vegetable supply in the world is more than double than vegetable intake, which supposes a significant waste of vegetables, in addition to the agricultural residues produced. As sensitive food ...products, the reasons for this waste vary from the use of only a part of the vegetable due to its different properties to the product appearance and market image. An alternative high-added-value application for these wastes rich in cellulose could be the reduction in size to produce lignocellulose micro- and nanofibrils (LCMNF). In this sense, a direct treatment of greengrocery waste (leek, lettuce, and artichoke) to produce LCMNFs without the extraction of cellulose has been studied, obtaining highly concentrated suspensions, without using chemicals. After drying the wastes, these suspensions were produced by milling and blending at high shear followed by several passes in the high-pressure homogenizer (up to six passes). The presence of more extractives and shorter fiber lengths allowed the obtention of 5-5.5% leek LCMNF suspensions and 3.5-4% lettuce LCMNF suspensions, whereas for artichoke, only suspensions of under 1% were obtained. The main novelty of the work was the obtention of a high concentration of micro- and nanofiber suspension from the total waste without any pretreatment. These high concentrations are not obtained from other raw materials (wood or annual plants) due to the clogging of the homogenizer, requiring the dilution of the sample up to 1% or the use of chemical pretreatments.
Since May 2022, several nonendemic countries face a monkeypox outbreak, with clinic and epidemiological characteristics distinct from the classic ones. Primarily affecting the sexually active ...population, these cases present with mucocutaneous lesions mainly localized in perioral, genital, and anal areas. A retrospective study was conducted in a tertiary center in Lisbon, to characterize the population diagnosed with monkeypox infection with primarily mucosal involvement.
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•Lagrangian Mixing Simulation (LMS) method to characterise mixing is developed.•LMS is applied over a 2D CFD simulation in a CIJ reactor.•LMS results were used to characterise mixing: ...calculation of interfacial area generation and segregation scales.•LMS is able to simulate and compute even the smallest mixing scales.•LMS has short CPU time when compared to CFD mixing simulations.
This paper introduces Lagrangian Mixing Simulation (LMS), which is a new method that uses particles to track the flow front between two fluids in a mixer. The line formed by an ensemble of particles enables the calculation of the instantaneous rate of interfacial area generation between the fluids and the computation of segregation scales. LMS uses the Eulerian velocity field from CFD simulation, which has a spatial resolution determined from the flow dynamics, for the simulation of mixing at scales that are several orders of magnitude below the CFD gridscale. Since only the interface between the two fluids is simulated, the LMS is orders of magnitude faster than the flow field simulation. In this work, LMS is applied to 2D CFD simulations of the flow in Confined Impinging Jets (CIJ) reactors for Re = 100, 300 and 500. LMS shows that the interfacial area generation is exponential for chaotic flow regimes (Re = 300 and 500) and linear for steady flows (Re = 100). Moreover, LMS is able to simulate segregation scales smaller than 10−8 m, i.e., LMS result spans and overcomes the entire range of spatial scales that have physical meaning.
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•NETmix performance was assessed for dissimilar inlet flow conditions.•Similar outlet flowrates were obtained for all inlet flowrate ratios studied.•A uniform flow distribution is ...achieved after at least 10 NETmix rows.•Spectral analysis allowed to determine the frequency of oscillation of the flow.•Increasing Re led to an increase in the size of vortices in the NETmix chambers.
The mixing dynamics that occur inside the NETmix reactor have been previously thoroughly studied for equal feed streams distributed through the inlets. To broaden the applicability of this static mixer, this work intends to expand the knowledge of the mixing dynamics mechanisms for cases where dissimilar inlet flowrates are imposed. Computational Fluid Dynamics (CFD) tools were used to simulate flow dynamics experiments in a reduced NETmix geometry for different inlet flowrate ratios. The simulation results show that this reactor can attain the desirable condition of similar outlet flowrates for several dissimilar inlet flow conditions. A flow dynamics analysis enabled the determination of the natural frequency of oscillation of the flow and related it to the volume of the chambers occupied by vortices. Finally, the velocity fluctuations at the centre of NETmix chambers were characterised in terms of the intensity of turbulence.
Aqueous solutions of glycerol are widely used as model fluids in flow phenomena experiments. The design of these experiments involves the description of the physical properties of liquids and the ...refractive index matching using a salt, i.e., calcium chloride. The first part of this paper describes the physical properties of aqueous solutions of glycerol. Refractive index, viscosity, and density were measured for a mass fraction of glycerol in a range from 0 to 1 and compared to the data in the literature. In the second part, calcium chloride was added to aqueous solutions of glycerol, and the variations of density, viscosity, and refractive index with the mass fraction of calcium chloride were reported, which is a new contribution to literature. The main novelties of this work are (1) the development and validation of a set of equations to predict the rheological and physical properties of model fluids for flow studies involving dissimilar fluids; (2) the introduction of an algorithm to match the refractive index of fluids using calcium chloride. The model fluids are designed for large throughput experiments of industrial units, and low-cost solutions were considered. A Matlab script is provided that enables the easy implementation of this method in other works.
Product formulations for industrial processes are typically developed at laboratory scale. However, the mixing conditions are not easily mimicked in the laboratory. A rotational device is proposed in ...this study as a fast laboratory‐scale formulation development, which enables mimicking the mixing conditions in the industrial process. The geometrical configurations of the rotational device are from rheometry devices (plate‐plate and cone‐plate). The main advantages of this method are the small amounts of raw materials and shorter testing times. This methodology is applied to an industrial case study, the reaction injection molding (RIM) process. The mixing length scales evolution in the rotational rheometer were matched to those in RIM machines. The main novelty of this study is the introduction of a protocol that bridges the processing conditions at laboratory using small amounts of raw materials to high throughput continuous flow reactors.
ChannelCOMB, a consecutive flow distributor, was constructed by additive manufacturing (AM) for experimental validation. The feasibility of using AM was experimentally analyzed for two techniques: ...stereolithography (tolerance of 50 µm) and fused deposition modeling (tolerance of 100 µm). For the best ChannelCOMB configuration, SLA printing shows a maximum of ca. 4 % in flow deviation, while FDM has a maximum of ca. 15 %. Thus, the SLA technique promotes better flow uniformity due to the fabrication tolerance and material permeability. The results also show that the experimental flow distribution measured for the best ChannelCOMB configuration printed by SLA can be well predicted by both computational fluid dynamics simulations and a model based on resistance analogs proposed in a previous work.
Stereolithography (SLA) and fused deposition modeling were used to additively manufacture ChannelCOMB, a consecutive flow distributor. The SLA ChannelCOMB shows a smaller flow deviation, because SLA promotes better flow uniformity due to the lower fabrication tolerance and material impermeability. The flow distribution can be well predicted by CFD simulations and the resistance analog model.
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