Interfacial Surface Area Research Articles

Experimental comparison investigation on the performance analysis of desert crystal sand roses and sand grain as natural effective heat storage materials in conical solar distillers: 4E and sustainability analyses

Conical solar distillers represent one of the most important technologies for producing low-cost freshwater in remote areas. However, its drawback is its limited freshwater production due to heat loss, so the present study aims to use natural effective heat energy storage materials to reduce heat loss, improve productivity, and avoid the higher cost of producing freshwater. To achieve this goal, comparison investigations on the performance analysis of Desert Crystal Sand Roses and Sand Grain as natural effective heat storage materials in conical solar distillers to improve freshwater productivity and at the same time avoid the high cost of producing freshwater. To achieve this goal experimentally, three identical conical solar distillers were built and tested in El Oued, Algeria. The first is the classical conical solar distiller (CCSD). The second is the conical solar distiller with the Natural Desert Crystal Sand Roses (CSD-SR). The third is a conical solar distiller with the Natural Desert Sand Grain (CSD-SG). The experimental results demonstrated that incorporating the Desert Crystal Sand Roses as natural storage materials in the distiller basin represents an innovative design that is characterized by serving as corrugated surfaces to enhance the absorbed rates of solar rays and interface surface area with the basin water, in addition to representing effective heat energy storage materials. Where using the Desert Crystal Sand Roses (CSD-SR) increases the cumulative productivity to 9.29 L/m2 per day with an improvement of 95.58 % compared to CCSD. Also, the use of Desert Crystal Sand Roses (CSD-SR) improved the energy efficiency, exergy efficiency, and sustainability index by 94.45, 227.45, and 2.9 % compared to CCSD. Also, the exergo-economic analysis indicated that the annual energy and exergy outlets were 94.48 and 227.42 %, respectively. Additionally, the cost per liter of produced freshwater from CSD-SR was reduced by 48.61 % compared to CCSD.

Mass Transfer Resistance and Reaction Rate Kinetics for Carbohydrate Digestion with Cell Wall Degradation by Cellulase.

This paper introduces an enzymatic approach to estimate internal mass-transfer resistances during food digestion studies. Cellulase has been used to degrade starch cell walls (where cellulose is a significant component) and reduce the internal mass-transfer resistance, so that the starch granules are released and hydrolysed by amylase, increasing the starch hydrolysis rates, as a technique for measuring the internal mass-transfer resistance of cell walls. The estimated internal mass-transfer resistances for granular starch hydrolysis in a beaker and stirrer system for simulating the food digestion range from 2.2 × 107 m-1 s at a stirrer speed of 100 rpm to 6.6 × 107 m-1 s at 200 rpm. The reaction rate constants for cellulase-treated starch are about three to eight times as great as those for starch powder. The beaker and stirrer system provides an in vitro model to quantitatively understand external mass-transfer resistance and compare mass-transfer and reaction rate kinetics in starch hydrolysis during food digestion. Particle size analysis indicates that starch cell wall degradation reduces starch granule adhesion (compared with soaked starch samples), though the primary particle sizes are similar, and increases the interfacial surface area, reducing internal mass-transfer resistance and overall mass-transfer resistance. Dimensional analysis (such as the Damköhler numbers, Da, 0.3-0.5) from this in vitro system shows that mass-transfer rates are greater than reaction rates. At the same time, SEM (scanning electron microscopy) images of starch particles indicate significant morphology changes due to the cell wall degradation.

Interactions of clathrate hydrate promoters sodium dodecyl sulfate and tetrahydrofuran investigated using 1H diffusion nuclear magnetic resonance at hydrate-forming conditions.

Thermodynamic hydrate promoters and kinetic hydrate promoters can be used to reduce the P-T conditions for clathrate hydrate synthesis to decrease the nucleation induction time while increasing growth rates. Two commonly used promoters for hydrate research are tetrahydrofuran (THF) and sodium dodecyl sulfate (SDS), which can increase the overall hydrate promotion when used in tandem as compared to individually. There are several molecular theories regarding how SDS promotes hydrate growth. This study explores the micellular theory, for which hydrate formation depends on surfactant aggregates (micelles) at a critical micelle concentration (CMC) to increase the interfacial surface area. The micellular theory is the most investigated and criticized surfactant hydrate promotion theory. To address questions related to micellar behavior, this study investigates the intermolecular behavior between SDS and THF for the identification of micelles at hydrate-forming conditions. The systems explored contained THF at 3 and 5 wt. % with varying concentrations of SDS below and above the CMC. Several methods including a qualitative visual method, conductivity, interfacial tensiometry, 13C Liquid-state Nuclear Magnetic Resonance (NMR) spectroscopy, and 1H diffusion NMR spectroscopy were evaluated at temperatures below the Krafft point of SDS and above 0 °C. The presence of THF at low concentrations decreased the critical temperature for the formation of SDS micelles, where SDS is solubilized in THF/water solution at hydrate-forming temperatures without precipitation. The CMC of SDS was decreased significantly even at hydrate-forming conditions. Mixed surfactant-cosolvent micellular behavior of SDS in the presence of low concentrations of THF was confirmed at hydrate-forming conditions above 0 °C.

Performance of mesoporous ceria supported Ru catalysts for oxidative degradation of aqueous solution of plastic monomer bisphenol A in a fixed bed flow reactor: Structure-activity insights, optimization of reaction conditions, kinetics, catalyst stability, and characterization

One of the important defects is the oxygen vacancy on metal oxide surfaces, and the defects function as the active sites in different catalytic reactions. Herein, Ru/CeO2-rod and Ru/CeO2-cube catalysts were prepared via the ESI method, and CeO2-rod and CeO2-cube supports were synthesized by hydrothermal processes. The activity of these catalysts was tested in a high-pressure fixed-bed reactor, and the oxidative degradation of industrial organic raffinate containing the plastic chemical bisphenol A (BPA) was compared with their oxygen vacancy concentration estimated after calcination. The Ru/CeO2-rod catalyst showed higher catalytic activity with 90 % BPA conversion at 453 K, 30 bar, 0.5 % Ru metal content, 15 O2 to BPA molar ratio, and 2 g−1.h−1 BPA feed weight hourly space velocity (WHSV). In contrast, 80 % BPA degradation was achieved using the Ru/CeO2-cube catalyst under similar reaction conditions. The higher oxygen vacancy concentration and the higher interfacial surface area between metal and the support of the CeO2-rod supported Ru catalyst triggered the higher BPA degradation at low oxidation conditions. Besides, the atomic ratio, Ce3+/Ce4+, is lower in the Ru/CeO2-rod catalyst than that of the Ru/CeO2-cube catalyst, indicating the higher Ce4+ available in the catalyst, leading to the higher degradation of BPA. Moreover, the Ru/CeO2-rod catalyst possesses {111} planes that boost the generation of energetic Ru to improve the pursuit of the catalyst. The Weisz-Prater modulus and Thiele modulus values indicated that the surface reaction is the rate limitation step and there is no diffusion limitation. TEM, HRTEM, XPS, Raman, H2-TPR, XRD, CO chemisorption and BET surface area analyzers were used to characterize the catalysts.

Carbon fiber fabrics functionalized with monoclinic CuO nanostructures using seed-assisted hydrothermal growth treatment

The woven carbon fibers (WCF) fabrics were functionalized by growing copper-oxide (CuO) nanostructures using Seed-assisted hydrothermal technique. The effective growth of CuO on surface hydrolyzed WCF samples were achieved by seeding followed by growth treatment in the prepared precursor solution. The impact of hydrothermal process parameters such as number of seeding cycles, duration of growth treatment and molar concentration of growth solution were studied by performing 96 set of experiments with three repetitions. In this work detailed analysis of structural, morphological, and elemental attributes of the CuO-coated WCF fabrics samples have been done. The WCF fabrics were uniformly coated with monoclinic CuO nanostructures having nanopellets, nanoflakes, nanowires, and nanoflowers morphologies. Different characterization techniques such as field emission scanning electron microscope, energy dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, FT-IR spectroscopy and thermo-gravimetric analyzer were used to study different attributes of CuO-modified WCF samples. The number of seeding treatments and the length of growth treatment had a significant impact on growth of CuO nanostructures on WCF. The detailed analysis exhibits that the developed CuO-modified WCF samples may enhance interfacial surface area, bonding capacity and reduce void content by allowing nanostructures to cross-link together and with polymer matrix while fabricating composite materials.

BaTaO2N and quantum dots-based CuO nanocomposites for HER by solar electrochemical water splitting

Barium tantalum oxynitride (BaTaO2N) has been demonstrated to be an attractive catalyst for photo-electrochemical water splitting, especially oxygen evolution reactions. However, the hydrogen production rates and charge transfer resistances of BTN leave much to be desired from a practical standpoint. In fact, it has never been reported for photocathode applications. On the other hand, CuO has been reported for hydrogen evolution reactions. Given this, here nanocomposites of BaTaO2N and copper oxide quantum dots (CuO QDs), where the latter are digestively ripened, are reported for photoelectrochemical water splitting on a carbon paper substrate. To assess the role of ultra-small quantum dots, composites of commercially available CuO nanoparticles with BaTaO2N were also tested. BaTaO2N and CuO QD nanocomposites performed well and showed a high photocurrent density of 3.1 mA cm−2 at 0 V vs RHE. This was also accompanied by reduced charge transfer resistance (225.4 Ω) due to the high interfacial surface area provided by nanoscopic CuO on BaTaO2N.

Built‐In Electric Field Enhancement Strategy Induced by Cross‐Dimensional Nano‐Heterointerface Design for Electromagnetic Wave Absorption

AbstractNano‐heterointerface engineering has been demonstrated to influence interfacial polarization by expanding the interface surface area and constructing a built‐in electric field (BEF), thus regulating electromagnetic (EM) wave absorption. However, the dielectric‐responsive mechanism of the BEF needs further exploration to enhance the comprehensive understanding of interfacial polarization, particularly in terms of quantifying and optimizing the BEF strength. Herein, a “1D expanded 2D structure” carbon matrix is designed, and semiconductor ZnIn2S4 (ZIS) is introduced to construct a carbon/ZIS heterostructure. The cross‐dimensional nano‐heterointerface design increases interface coupling sites by expanding the interface surface area and induces an increase in the Fermi level difference on both sides of the interface to modulate the distribution of interface charges, thereby strengthening the BEF at the interface. The synergistic effect leads to excellent EM absorption performance (minimum reflection coefficient RCmin = −67.4 dB, effective absorption bandwidth EAB = 6.0 GHz) of carbon/ZIS heterostructure. This work introduces a general modification model for enhancing interfacial polarization and inspires the development of new strategies for EM functional materials with unique electronic behaviors through heterointerface engineering.

Dilute Donor Organic Solar Cells Based on Non-fullerene Acceptors.

The advent of small molecule non-fullerene acceptor (NFA) materials for organic photovoltaic (OPV) devices has led to a series of breakthroughs in performance and device lifetime. The most efficient OPV devices have a combination of electron donor and acceptor materials that constitute the light absorbing layer in a bulk heterojunction (BHJ) structure. For many BHJ-based devices reported to date, the weight ratio of donor to acceptor is near equal. However, the morphology of such films can be difficult to reproduce and manufacture at scale. There would be an advantage in developing a light harvesting layer for efficient OPV devices that contains only a small amount of either the donor or acceptor. In this work we explore low donor content OPV devices composed of the polymeric donor PM6 blended with high performance NFA materials, Y6 or ITIC-4F. We found that even when the donor:acceptor weight ratio was only 1:10, the OPV devices still have good photoconversion efficiencies of around 6% and 5% for Y6 and ITIC-4F, respectively. It was found that neither charge mobility nor recombination rates had a strong effect on the efficiency of the devices. Rather, the overall efficiency was strongly related to the film absorption coefficient and maintaining adequate interfacial surface area between donor and acceptor molecules/phases for efficient exciton dissociation.

A sensitive NH3 chemiresistive sensor with wide detection range: Employing a MOF-derived mesoporous carbon composite with polyaniline

Designing sensing materials with effective porous structure and compositions is a crucial strategy for constructing high-performance gas-sensitive devices. Herein, a dodecahedral mesoporous carbon derived from metal-organic frameworks (CMOF), e.g. Zeolitic Imidazolate Framework-8 (ZIF-8) derived porous carbon (ZIF-8-C) was prepared, and subsequently, three-dimensional (3D) hollow dodecahedral ZIF-derived carbon-polyaniline (PANI) based (ZCPx, x representing the mass fraction of ZIF-derived carbon) hierarchical hybrid materials were constructed by introducing protonated polyaniline on the surface of MOF carbon via in-situ oxidative polymerization. The MOF-derived structure provides a substantial interface surface area for the hybrid material, enabling rapid adsorption and charge transfer, along with essential structural stability. The 3D hollow ZCP50 hybrid material prepared exhibits a wide detection range (0.1–500 ppm), repeatability, acceptable long-term stability, and an 8.3 times response enhancement versus PANI. The above performance is attributed to the significant synergistic effect between ZIF-8-C and PANI. The unique design of this 3D framework holds promising potential for the commercial application of room-temperature gas sensors.

A mechanistic kinetic model for lipid oxidation in Tween 20-stabilized O/W emulsions

Models predicting lipid oxidation in oil-in-water (O/W) emulsions are a requirement for developing effective antioxidant solutions. Existing models do, however, not include explicit equations that account for composition and structural features of O/W emulsions. To bridge this gap, a mechanistic kinetic model for lipid oxidation in emulsions is presented, describing the emulsion as a one-dimensional three phase (headspace, water, and oil) system. Variation in oil droplet sizes, overall surface area of oil/water interface, oxidation of emulsifiers, and the presence of catalytic transition metals were accounted for. For adequate predictions, the overall surface area of oil/water interface needs to be determined from the droplet size distribution obtained by dynamic and static light scattering (DLS, SLS). The kinetic model predicted well the formation of oxidation products in both mono- and polydisperse emulsions, with and without presence of catalytic transition metals.

Influence of pin-perforation shape on thermohydraulic performance of circular pin-fin heat sinks under turbulent flow

The impact of pin-perforation shape on the thermohydraulic performance of circular pin–fin heat sinks (CPFHS) under turbulent flow conditions is numerically assessed using a computational fluid dynamics software. The convective heat transfer efficiency, hydraulic resistance, and thermohydraulic performance of four pin-perforation shapes: square diamond, triangle, hexagon, and circle, are evaluated under various turbulent flow conditions (Reynolds number between 24,484 to 55,088). The sizes of all pin-perforation shapes are under a constraint that the ratio of the air–solid interfacial surface area to the total volume of pin-perforated CPFHS must be the same. The results show that all pin-perforated CPFHS demonstrate a higher Nusselt number compared to unperforated CPFHS. Those with circular perforations exhibit the highest Nusselt number with up to 39% improvement compared to unperforated CPFHS, followed by those with hexagonal, triangular, and diamond perforations, respectively. The Nusselt numbers correlate with the ease of fluid flow within perforations which is expressed using the average air velocities through perforations. In terms of hydraulic resistance, all pin-perforated CPFHS exhibit a reduction in friction factor compared to unperforated CPFHS. Among these, the largest decrease in friction factor, up to 15.8%, is observed in CPFHS featuring circular perforations, followed by those with hexagonal, diamond, and triangular perforations, respectively. The friction factors are influenced by the ratio of perforation perimeter to cross-sectional area. All pin-perforated CPFHS have a thermal performance factor greater than 1, indicating an improvement in thermohydraulic performance compared to unperforated CPFHS. CPFHS with circular perforations yield the highest thermal performance factor, reaching up to 1.44, followed by hexagonal, triangular, and diamond pin configurations, in descending order. With increasing Reynolds numbers, thermal performance factors of pin-perforated CPFHS initially rise, then gradually decline, suggesting that thermohydraulic advantages due to pin–fin perforations are diminishing as the flow become more turbulent.

Influence of contouring the lithium metal/solid electrolyte interface on the critical current for dendrites

Efforts to avoid dendrites by increasing the interfacial surface area to lower local current densities are limited by significant local pressure accumulation associated with the topography of any surface contouring.

Vertically Aligned Nanocomposite Thin Films Incorporating 3D-Architectures for Micro-Battery Applications

Vertically aligned nanocomposite (VAN) thin films have shown strong potential in oxide nanoionics but are yet to be explored in detail in solid-state battery systems [1,2]. VANs, typically grown by pulsed laser deposition (PLD), are chessboard-like structures comprised of pillars of one phase embedded in a matrix the second phase. They form by solid-state thermodynamic self-assembly, allowing the spontaneous formation of interdigitated battery components in a single deposition without additional processing steps such as etching. Their 3D architectures are attractive because they may allow enhancements in capacity, current and power densities [3]. Furthermore, VAN films grow with a preferential orientation, allowing for selective growth of the optimum crystallographic orientation for high performance by altering the substrate phase and/or orientation. Also, owing to their large interfacial surface areas, VAN could serve as models to study interfaces and solid-electrolyte interphase formation during cycling due to their high interfacial surface areas.In this poster, first we present highly crystalline and epitaxial vertically aligned nanocomposite PLD films comprised of a LixLa0.32±0.05(Nb0.7±0.1Ti0.32±0.05)O3±δ-Ti0.8±0.1Nb0.17±0.03O2±δ-anatase (LL(Nb,Ti)O-(Ti,Nb)O2) electrolyte/anode system, the first anode VAN battery system reported (Figure 1) [4]. This system exhibits an order of magnitude increased Li+ ionic conductivity over that in bulk Li3xLa1/3-xNbO3 (LLNO) and is comparable with the best available Li3xLa2/3-xTiO3 (LLTO) pulsed laser deposition films. Then, we will highlight the considerations and challenges that VANs pose, and how to overcome them [5]. Finally, we will also present our recently submitted work on VAN based cathodes [6]. Our carefully selected materials combination exhibits remarkable high-rate performance, achieving discharge capacities > 70 mAh g-1 up to ~200 C with clear redox behavior of the cathode-of-choice. The enhanced electrochemical performance is enabled by the 3D VAN architecture. Interestingly, we elucidate the relationship between pillar morphology and electrochemical performance, namely there is an optimum size and orientation of cathodic nanopillars such that high discharge capacity under high-rate regimes is possible. These works open up the possibility of incorporating VAN films into an all solid-state battery, either as electrodes or electrolytes, by the pairing of suitable materials.

(Invited) Different Designs for Ta-Doped Llzo Based Solid State Battery Prepared By Tape-Casting

One pathway for moving forward from current Li-ion battery technology based on organic liquid electrolytes to next-generation battery design can be implementation of solid state electrolyte along with Li metal based negative electrode. This step would result in a battery with higher energy density and improved safety.One promising candidate material for ceramic electrolyte is garnet-type oxide LLZO (Li7La3Zr2O12) due to its relatively good chemical stability which allows relaxed requirements for processing and handling. Additionally, the doped LLZO has sufficiently good Li+ ionic conductivity (0.1 – 1 mS/cm at room temperature) and exhibits (electro-)chemical stability with the electrode materials currently under focus. To achieve low resistance values, the LLZO electrolyte needs to be prepared as a thin layer with high density. In order to integrate fabrication of LLZO electrolyte into industrial manufacturing, tape-casting can be considered as one of the low-cost scalable method for producing ceramic layers.In this study tape-casting was used to produce Ta-doped LLZO electrolyte layers with relative density of 98% and total conductivity of 0.3 mS/cm at room temperature. In order to obtain Li/LLZO/Li symmetrical cells, interfacial treatment was used for surface of LLZO to achieve good contact and low interfacial resistance with Li metal electrode. Current densities up to 300 µA/cm2 were achieved during galvanostatic cycling for flat LLZO pellet sample at 40 °C. The cell was galvanostatically cycled with high stability for long term at current density of 100 µA/cm2.Another design that can be considered for LLZO-based solid state battery is porous-dense-porous multilayers. This architecture has the advantage to provide support for electrolyte layer allowing to reduce its thickness and also increases the interfacial surface area which will reduce interfacial resistance. The described design allows to obtain lower resistance for the solid state battery with higher accessible current densities (>1mA/cm2), thus providing higher performance.

Towards enhanced mechanical performance of Al/steel welded-brazed joints via laser surface texturing modification

Laser texturing is a promising technology with wide-ranging applications in surface processing. In this study, a nanosecond laser was used to ablate the surface of Q355 steel, creating grooves of varying depths by different processing times. Satisfactory Al/Steel joints were obtained under different groove depths (0 μm, 6 μm, 26 μm and 56 μm). Interfacial microstructure evolutions were investigated and the observed results indicated that introduction of texture would enhance interfacial specific surface area, promote degree of atomic diffusion, thicken interfacial IMCs (intermetallic metallic compounds) while maintain interfacial reaction (η-Fe2(Al,Si)5 + θ-Fe(Al,Si)3). Numerical simulations results illustrated that existence of texture would reduce interfacial peak residual stress, homogenize residual stress distribution and induce compressive stress in the groove. Highest strength of 111 MPa with the fracture mode of tough-brittle compound fracture was produced in the joint when laser texturing processing times were 20, which was nearly 40 % higher compared to the untreated joint (80 MPa). This study provides a novel method to improve joints mechanical properties for laser welding-brazing of Al/Steel system, which may also provide a theoretical reference for the application of other dissimilar metal systems.

Reinforced PDMS Elastomer Nanocomposites: Effectiveness of In Situ Nano-Silica Content on Flashover Voltage and Treeing Phenomena

Large interfacial surface area between the inorganic particles and the polymer matrix has made nanocomposites an interesting composition for a wide range of applications including high-voltage insulating materials. However, nanofiller dispersion is challenging and there is always a specific percolation threshold that narrows the particle content in a polymer dispersion. This research attempt to benefit the in-situ silica precipitation technique to avoid all problems associated with nanoparticle dispersion and furthermore introduce a technique to increase the nano-silica content. In this regard, elastomeric silicone nanocomposites loaded with various amount of nano-silica, low to high, is fabricated. It is revealed that the nanocomposite loaded with a high quantity of nano-silica particles exhibited high thermal stability and heat resistivity. Utilized as a coating, this nanocomposite could successfully increase the flashover voltage and present less damage after electrical discharges. Moreover, the electrical treeing investigation illustrates a different distribution of tree structure depending on nano-silica content which could be beneficial in diverse electrical insulating applications.

Ammonium perchlorate catalyzed with novel porous Mn-doped Co3O4 microspheres: superior catalytic activity, advanced decomposition kinetics and mechanisms

Mn-doped Co3O4 nanoparticles of 15 nm were developed via solvothermal synthesis. Mn@Co3O4 microspheres were developed via controlled annealing treatment at 600 °C. Mn@Co3O4 microspheres demonstrated an average diameter of 5.5 µm, with specific area (BET) of 73.7 m2 g−1. The pore diameter was centered at 13.1 nm, and the mean pore size was 16 nm; porous structure could secure extensive interfacial surface area. Mn@Co3O4 microspheres were integrated into ammonium perchlorate (AP) matrix. The catalytic activity of Mn@Co3O4 on AP decomposition was assessed via DSC and TGA/DTG. Whereas Mn@Co3O4/AP nanocomposite demonstrated decomposition enthalpy of 1560 J g−1, pure AP demonstrated 836 J g−1. While Mn@Co3O4/AP nanocomposite demonstrated one decomposition temperature at 310 °C,pure AP exposed two decomposition stages at 298 °C, and 453 °C. Decomposition kinetics was investigated via isoconversional (model free) and model fitting. Kissinger, Kissinger–Akahira–Sunose (KAS), integral isoconversional method of Ozawa, Flyn and Wall (FWO), and differential isoconversional method of Friedman. Mn@Co3O4/AP demonstrated apparent activation energy of 149.7 ± 2.54 kJ mol−1 compared with 173.16 ± 1.95 kJ mol−1 for pure AP. While AP demonstrated sophisticated decomposition models starting with F3 followed by A2, Mn@Co3O4/AP nanocomposite demonstrated A3 decomposition model. Mn@Co3O4 can expose active surface sites; surface oxygen could act as electron donor to electron deficient perchlorate group. Furthermore, Mn@Co3O4/AP could act as adsorbent of released NH3 gas with efficient combustion. This study shaded the light on Mn@Co3O4 as potential catalyst for AP decomposition.

3D Nanocomposite Thin Film Cathodes for Micro‐Batteries with Enhanced High‐Rate Electrochemical Performance over Planar Films

AbstractHigh energy and high power density rechargeable micro‐batteries are a necessity for powering the next generation of flexible electronics, internet of things, and medical technology devices. In theory, significant improvements in the capacity, current and power densities of micro‐batteries would result if 3D architectures with enhanced interdigitated component interface areas and shortened ion diffusion path‐lengths were used. Further gains are achievable if the materials utilized have high crystalline quality and are preferentially oriented for fast lithium intercalation. In this work, this is achieved by creating epitaxial thin film cathodes comprised of nanopillars of LiMn2O4 (LMO) embedded in a supporting matrix of electronically conducting SrRuO3 (SRO). The first electrochemical study of such a 3D vertically aligned nanocomposite (VAN) that displays clear cathode redox signatures is provided, and demonstrates remarkable capacity retention under high‐rate regimes. The electrochemical performance is shown to be dependent on the nanopillar topography, namely the crystallographic orientation, nanopillar dimensions, and electrode/electrolyte interfacial surface area. This work offers a pathway to realizing 3D architectured micro‐batteries with high‐capacity retention under high‐rate conditions enabling fast charge capabilities.

Computational investigation on the flow and mass transfer properties inside ejector of loop reactor based on CFD-PBM simulation

Conventional stirred kettle reactors suffer from inadequate gas-liquid mixing in many production processes, and their reaction rates are greatly limited. The loop reactor can achieve high mass transfer rates with low energy consumption. It is well suited for multiphase reactions with limited mass transfer and has the advantage of being excellent sealing and low cost. In this paper, ejector as the core of the loop reactor was investigated. Combining the Computational Fluid Dynamics (CFD) and Population Balance Model (PBM), the industrial-scale ejector model was constructed. The detailed motion behavior of bubbles and bubble size distribution were predicted. Due to the entrainment of the liquid phase, the gas enters the suction chamber and throat of the ejector, where the gas is mainly sheared and broken, providing a large specific surface area of the gas-liquid interface. Moreover, the flow and transfer properties were closely related to parameters such as nozzle-throat diameter ratio and liquid inlet velocity. Based on the results of the simulation, the gas-liquid mass ratio and the volumetric mass transfer coefficient were correlated with the structure and process parameters, and the correlation model was obtained, which provides guidance for the design of the loop reactor.

Preparation of Free-Surface Hyperbolic Water Vortices.

Free surface vortices are present in industry in flow regulation, energy dissipation, and energy generation. Although investigated extensively, detailed experimental data regarding free surface vortices are lacking, particularly regarding the turbulence at the interface. The present paper reports on a special type of free surface vortex first proposed by Walter Schauberger in the 1960s that has an oxygen volumetric mass transfer coefficient exceeding the value of similar systems. This special type of vortex forms in a hyperbolic funnel. Different stable regimes can be stabilized with different hydraulic characteristics. Other advantages of this technology are its energy efficiency, simple design, and scalability. The flow in this hyperbolic funnel is characterized by strong turbulence and an increased surface area of the air-water interface. The local pressure strongly varies along the surface, resulting in a pronounced wavey air-water boundary layer. Due to the helical flow, these perturbations move inward, pulling the boundary layer with them. The resultant pressure gradient draws a certain air volume into the water vortex. The construction of the basic hyperbolic funnel setup and operational examples, including high-speed visualization for three different stable regimes, are presented in this work.