Enhanced Mass Transfer Research Articles

N-doped porous graphite with multilevel pore defects and ultra-high conductivity anchoring Pt nanoparticles for proton exchange membrane water electrolyzers

Water electrolysis for hydrogen production offers a promising solution to future energy crises and environmental challenges. Although platinum is an efficient catalyst for hydrogen evolution reactions (HERs), its high cost and stability challenges limit its widespread use. A novel platinum-based catalyst, comprising platinum nanoparticles on nitrogen-doped porous graphite (Pt-N-porous graphite), addresses these limitations. This catalyst prevents nanoparticle aggregation, provides a high specific surface area of 1308 m2 g−1, and enhances mass transfer and active site exposure. Additionally, it exhibits superior electrical conductivity compared to commercial Pt-C, enhancing charge transfer efficiency. The Pt-N-porous graphite catalyst achieves an overpotential of 99 mV at 100 mA cm−2 and maintains stable performance after 10000 cycles. Applied as a catalyst-coated membrane (CCM) in a proton exchange membrane (PEM) electrolyzer, it demonstrates excellent performance. Thus, the industrially synthesizable Pt-N-porous graphite catalyst holds great potential for large-scale energy applications.

Mn-Zr promoted CaCO3 porous microspheres for enhanced performance in direct solar-driven calcium looping

The Calcium looping thermochemical reaction directly driven by solar energy effectively addresses the problem of efficient energy storage of concentrated solar power plants (CSP) by shortening the energy conversion path. But new requirements are put forward for energy storage materials, including high solar radiation absorption, high cycling stability and fast kinetics. To meet these challenges, we have designed porous microsphere structures for the purpose of enhancing mass transfer and the capture of solar radiation. Additionally, Zr and Mn oxides with elevated Tammann temperatures were incorporated to stabilize the morphology and prevent sintering. The synthesized porous microspheres retained abundant mesoporous channels on the surface even after undergoing 20 cycles. The addition of Mn oxide significantly enhances solar spectral absorptivity, achieving an impressive 82.88 % absorbance. The incorporation of Mn and Zr oxides increased the sintering resistance, specific surface area and porosity of CaO/CaCO3, especially in the 10–100 nm range, which accelerated the CO2 transport during carbonation. These enhancements significantly improve the chemical control stage of the carbonation reaction, as further supported by kinetic models. After 50 cycle experiments at 800 °C, the energy storage density of the sample remains at 1074 kJ/kg, which is 1.86 times that of the undoped CaCO3. This study provides a new way to design CaCO3 materials suitable for CSP applications.

A novel leaf bionic flow field with structured multi-level channel based on Murray's law in proton exchange membrane fuel cell for enhanced mass transfer

The design of flow field has a significant impact on the performance of proton exchange membrane fuel cells (PEMFCs). In this study, a novel leaf bionic flow field is designed and optimized based on Murray's law. The power consumption ratio is first used in the bionic PEMFC. Additionally, an evaluation criterion, the mass transfer efficiency evaluation criterion (MTEEC), is proposed to characterize mass transfer efficiency, and field synergy theory is used to analyze performance differences in mass transfer among various flow fields. The results demonstrate that adding multi-level channel and obstacles in the flow field significantly enhances cell output performance and reduces voltage losses in mass transfer regions. Applying Murray's law to distribute multi-level channel improves the uniformity of oxygen concentration distribution in the flow field and alleviates under-rib water accumulation. Compared to the secondary stream flow field (SSFF), the structure mesh of leaf bionic flow field (SMLBFF) demonstrates a nearly 19% increase in current density output at 0.45 V. SMLBFF exhibits an 81.51% increase in convective mass transfer rate compared to SSFF at 0.4 V. Moreover, the MTEEC of SMLBFF shows improvements of 179.68% at 0.5 A/cm2 and 135.43% at 1.0 A/cm2, compared to SSFF.

Unraveling the corrosion behavior and corrosion scale evolution of N80 steel in high-temperature CO2 environment: The role of flow regimes

During CO2 transportation and storage, metal equipment such as oilfield pipelines suffers from severe CO2 corrosion, especially in harsh downhole injection equipment. In this study, we investigated the corrosion behavior of oil well tubing in a high-temperature, high-pressure (HTHP) CO2-containing environment. The evolution of the corrosion scale was also examined under different flow regimes. The results reveal a lower corrosion rate at 150 °C compared to 80 °C under different flow regimes, with localized corrosion intensifying as temperature and rotational speeds (vrs) increase. The temperature also induces the corrosion scale conversion of aragonite-type CaCO3 (80 °C) to calcite-type CaCO3 (150 °C). Specifically, the variation of the corrosion rate and the corrosion scale evolution can be attributed to the vortices within the reactor. The intact vortex cells enhance mass transfer while also promoting nucleation and growth of CaCO3. However, when vrs exceeds the critical Reynolds number, the vortex cells are disrupted, resulting in viscous dissipation and a reduced corrosion rate.

Laser-Regulated Iridium-Diffused Nitrogen-Carbon Sites for Enhanced Hydrazine-Assisted Alkaline Seawater Splitting and Zinc-Hydrazine Batteries.

The current study presents a quick and simple method for synthesizing Ir nanoclusters decorated on an N-doped carbon (NC) matrix via pulsed laser ablation in liquid, followed by pyrolysis. The resulting Ir-NC material acts as a dual-functional electrocatalyst, efficiently facilitating hydrogen generation through the hydrazine oxidation reaction (HzOR) and the hydrogen evolution reaction (HER) in alkaline seawater. The optimized Ir-NC-2 catalyst exhibits a low operating potential of 23mV versus the reversible hydrogen electrode for HzOR and a remarkably low overpotential of 24mV for HER, achieving a current density of 10mAcm-2 in alkaline seawater, surpassing the performance of the Pt/C catalyst. Notably, the Ir-NC-2 catalyst also demonstrates superior dual-functionality in overall hydrazine-assisted seawater splitting, requiring only 0.1V at 10mAcm-2 while maintaining stability. Moreover, density functional theory calculations reveal that the strong electronic interaction between the Ir nanoclusters and the NC matrix enhances mass transfer and electron conductivity, significantly boosting HER activity and accelerating the kinetics of hydrazine dehydrogenation. Consequently, the Ir-NC-2 catalyst performs efficiently in a Zn-hydrazine battery, achieving high energy efficiency of 95.5% and demonstrating excellent stability for 120h (360 cycles), indicating its potential for practical applications.

Novel ellipsoid-like granules exhibit enhanced anammox performance compared to sphere-like granules

Anammox granular sludge (AnGS) serves as an important platform for cost-effective nitrogen removal from wastewater. Different to the traditionally sphere-like granules, a novel type of AnGS in a unique ellipsoid-like shape was obtained through enhancing shear force. The ellipsoid-like AnGS significantly exhibited a smaller aspect ratio (-25.1 %) and granular size (-11.8 %), compared to traditional sphere-like AnGS (p < 0.01). Comprehensive comparisons showed that ellipsoid-like AnGS possessed a significantly higher extracellular polymeric substances (EPS) content and strength, as well as an enhanced mass transfer and a higher viable bacteria proportion due to the larger substrate permeable zone (p < 0.01). Additionally, the anammox bacterial abundance (Candidatus Kuenenia) was 12.2 % higher in ellipsoid-like AnGS than in sphere-like AnGS. All these characteristics of ellipsoid-like AnGS jointly increased the specific anammox activity by 29.0 % and nitrogen removal capacity by 22.6 %, compared to sphere-like AnGS. Further fluid field simulation suggested the enhanced flow shear on the side surface of AnGS likely drove the formation of ellipsoid-like AnGS. The higher shear force on the side surface led to an increase of EPS content (especially hydrophobic protein) and elastic modulus, thus constraining lateral expansion. This study sheds light on impacts of granular shape, an overlooked morphological factor, on anammox performance. The ellipsoid-like AnGS presented herein also offers a unique and promising aggregate to enhance anammox performance.

Porous Carbon‐Supported Catalysts for Proton Exchange Membrane Fuel Cells

AbstractProton exchange membrane fuel cells (PEMFCs) are crucial for the efficient utilization of hydrogen. Currently, their efficiency is mainly limited by the slow kinetics of the cathode oxygen reduction reaction (ORR) and the poisoning effect between ionomers and catalytic sites, particularly with Pt‐based catalysts. Recent works suggest that the emerging porous carbon‐supported catalysts hold promise in mitigating these challenges by ensuring fast kinetics while alleviating the poisoning. This review examines porous carbon‐supported catalysts for PEMFC cathodes, covering synthesis methods, structure and performance evaluation, and future prospects, with an emphasis on the influence of porous carbon support on PEMFC performance. On one hand, the rational design of pore structure in carbon support can help optimize the location of the active sites and enhance mass transfer. On the other hand, diverse pore structures provide a platform for gaining a deeper understanding of the mechanisms behind microscale mass transfer and reaction at the three‐phase boundaries. This review aims to inspire innovative strategies for the precise synthesis of porous carbon‐supported catalysts with various pore structures to further boost PEMFC performance.

Mass-transfer Outbursts Reborn: Modeling the Light Curve of the Dwarf Nova EX Draconis

EX Draconis is an eclipsing dwarf nova that shows outbursts with moderate amplitude (≃2 mag) and a recurrence timescale of ≃20–30 days. Dwarf novae outbursts are explained in terms of either a thermal-viscous instability in the disc or an instability in the mass-transfer rate of the donor star (MTIM). We developed simulations of the response of accretion discs to events of enhanced mass transfer, in the context of the MTIM, and applied them to model the light curve and variations in the radius of the EX Dra disc throughout the outburst. We obtain the first modeling of a dwarf nova outburst by using χ 2 to select, from a grid of simulations, the best-fit parameters to the observed EX Dra outbursts. The observed time evolution of the system brightness and the changes in the radius of the outer disc along the outburst cycle are satisfactorily reproduced by a model of the response of an accretion disc with a viscosity parameter α = 4.0 and a quiescent mass-transfer rate Ṁ2(quiescence)=4.0×1016 g s−1 to an event of width Δt = 6.0 × 105 s (∼7 days) where the mass-transfer rate increases to Ṁ2(outburst)=1.5×1018 g s−1.

Theoretical Study of the Influence of Electroconvection on the Efficiency of Pulsed Electric Field (PEF) Modes in ED Desalination

Pulsed electric field (PEF) modes of electrodialysis (ED) are known for their efficiency in mitigating the fouling of ion-exchange membranes. Many authors have also reported the possibility of increasing the mass transfer/desalination rate and reducing energy costs. In the literature, such possibilities were theoretically studied using 1D modeling, which, however, did not consider the effect of electroconvection. In this paper, the analysis of the ED desalination characteristics of PEF modes is carried out based on a 2D mathematical model including the Nernst–Planck–Poisson and Navier–Stokes equations. Three PEF modes are considered: galvanodynamic (pulses of constant electric current alternate with zero current pauses), potentiodynamic (pulses of constant voltage alternate with zero voltage pauses), and mixed galvanopotentiodynamic (pulses of constant voltage alternate with zero current pauses) modes. It is found that at overlimiting currents, in accordance with previous papers, in the range of relatively low frequencies, the mass transfer rate increases and the energy consumption decreases with increasing frequency. However, in the range of high frequencies, the tendency changes to the opposite. Thus, the best characteristics are obtained at a frequency close to 1 Hz. At higher frequencies, the pulse duration is too short, and electroconvective vortices, enhancing mass transfer, do not have time to develop.

Enhancement of H2-water mass transfer using methyl-modified hollow mesoporous silica nanoparticles for efficient microbial CO2 reduction

Inorganic-microbial hybrid catalysis is an emerging technology that uses electrical energy to drive microorganisms to reduce CO2 into high value-added compounds, and it has broad application prospects in CO2 reduction. However, the low current density (production yield) limits its practical application. Hydrogen-mediated inorganic-microbial hybrid catalysis system can achieve higher current density, but it is limited by low H2 mass transfer. Here, silica nanoparticles were used to enhance the hydrogen mass transfer for highly efficient CO2 reduction. Solid silica (SN), mesoporous silica (MSN), hollow mesoporous silica (HMSN), and methyl-modified hollow mesoporous silica (MHMSN) were firstly prepared and tested for the enhancement of hydrogen mass transfer. Of these, MHMSN nanoparticles at a concentration of 0.3 wt% were the best at enhancing gas-liquid mass transfer, the volumetric mass transfer coefficient (KLa) and saturated dissolved hydrogen concentration of H2 are 0.53 min-1 and 1.81 mg l-1, respectively. Compared with the control group without added nanoparticles, MHMSN significantly increased the solubility and KLa of H2. This can be attributed that the addition of MHMSN promoted the detached process of hydrogen bubbles from the electrode surface, which made the diameter of hydrogen bubbles smaller, increased the gas-liquid mass transfer area, and strengthened the mass transfer process of H2. Furthermore, it was added to the inorganic-microbial hybrid catalysis system to effectively promote the microbial carbon reduction process, achieving a polyhydroxybutyrate (PHB) yield of up to 700 mg l-1, and the electron utilization rate and CO2 conversion rate were 51 % and 58 % higher than the control group, respectively. These results demonstrated that the addition of MHMSN is an effective approach to enhancing the performance of H2-mediated inorganic-microbial hybrid catalysis system.

Novel Venturi injector reactor design and application in ammonia nitrogen wastewater treatment

The Venturi injector reactor has a robust and durable design and is highly efficient and reliable. The flow field control in the Venturi reactor is an effective way to enhance gas−liquid mass transfer. In this study, a novel Venturi injector reactor with an expandable self-priming air inlet and a second water inlet in the diffusion section was designed by combining particle image velocimetry (PIV) experiments with a computational fluid dynamics simulation. This novel design increased the gas holdup, generated smaller and more uniform bubbles, and enhanced mass transfer. Furthermore, we applied the novel Venturi device to the biological degradation of ammonia nitrogen wastewater. The total gas holdup in the novel Venturi was higher than in the conventional Venturi injector reactor by 0.0056 on average. The minimum bubble diameter was approximately 0.71 mm. Moreover, the ammonia nitrogen removal efficiency of the novel Venturi equipment with the second inlet was 2 and 1.1 times higher than that of conventional aeration and conventional Venturi device, respectively. This study provides a theoretical basis and practical significance for improving the performance and efficient degradation of the ammonia nitrogen concentration in Venturi injector reactors.

Roles of lignin in pore development during activation of peach wood

Cellulose, hemicellulose, and lignin are major components in typical woody biomasses. They have varied reaction networks in activation and thus contribute to pore development in different ways. Removal of one component might significantly affect pore characteristics of resulting activated carbon (AC). This was investigated herein by activation of peach wood (PW), delignified peach wood (DLPW), lignin, and a mixture of lignin/DLPW with K2C2O4 at 800 °C. The results disclosed that delignification increased abundance of aliphatic structures relatively and enhanced mass transfer of volatiles and permeability of K2C2O4 through creating voids. These features together intensified cracking reactions in activation of delignified PW, enhancing bio-oil yield (60.9 vs 56.1 % from PW), diminishing production of AC (17.4 vs 20.2 % from PW), promoting pore development (1218.5 versus 1099.4 m2g-1 from PW), enlarging pore size of micropores and creating more mesopores and macropores in AC. This rendered the AC of superior performance for adsorption of phenol. Co-activation of DLPW and lignin suggested that reactions between DLPW-derived volatiles and lignin-derived char formed carbonaceous deposits that filled pores of AC, diminishing overall specific surface area. The characterization of the activation process with in-situ IR technique indicated that more intensive cracking reactions in activation of DLPW even hindered aromatization but facilitated pore development.

Silicone‐Assisted Autonomous Growth of Strainless Perovskite Single Crystals for Integrated Low‐Dose X‐Ray Imaging Arrays

AbstractMetal halide perovskite single crystals (SCs) have emerged as promising candidates for high‐performance X‐ray detectors. However, mitigating the adverse effects of thermal and interfacial stress during SC growth remains a significant challenge. In this study, the solution growth of high‐quality perovskite SCs using silicone containers through a constant‐temperature autonomous crystallization process is presented. Unlike conventional hard glass vessels, soft silicone containers significantly reduce the negative impact of thermal and interfacial stress on SC growth. Additionally, the microporous nature of silicone containers permits solvent leakage, facilitating autonomous SC growth at constant temperatures. The hydrophilic surface of the silicone further increases the interfacial nucleation barrier and enhances mass transfer, promoting the rapid growth of larger SCs. This multifaceted approach results in MAPbBr3 SCs with an exceptionally low defect density of 2.15×108 cm−3 and an optimal full‐width‐at‐half‐maximum of X‐ray diffraction rocking curves at 19.04 arcsec, consequently leading to an ultralow X‐ray detection limit of 850 pGyair s−1 for the X‐ray detectors. The superior quality of the SCs, combined with a low‐temperature flip‐chip bonding process, enables the integration of the crystals with pixelated arrays on a printed circuit board for both single‐photon detection and low‐dose X‐ray imaging.

Enhancing heat and mass transfer in MHD tetra hybrid nanofluid on solar collector plate through fractal operator analysis

Improved solar heat transfer methods are needed for the widespread use of solar energy. Due of their exceptional thermal characteristics, nanofluids have received a great deal of interest in this field. This research examines the use of tetra hybrid nanofluids in solar applications, with an emphasis on heat and mass transport properties. Due to their advantageous thermal characteristics, these nanofluids are well-suited for solar power production and other thermal applications. Accurate results for velocity, concentration, and temperature profiles are produced thanks to the model's use of fractal fractional derivatives and the Crank-Nicholson method for obtaining numerical solutions. In order to learn how different variables affect heat transport, parametric experiments are performed. The results show that tetra hybrid nanofluids greatly improve heat transfer performance over standard nanofluids. This improvement helps flat-plate solar collectors absorb more sunlight and increase their overall efficiency. The rate of mass transfer between phases may be quantified in the design and research of chemical reactors using the Sherwood number, an important quantity in chemical engineering. Its value is shown in a number of processes, including extraction, distillation, and catalytic reactions.

Enhancing the biodegradation of hydrophobic volatile organic compounds: A study on microbial consortia adaptation and the role of surfactants

The emission of hydrophobic Volatile Organic Compounds (VOCs) is a serious environmental issue. Typically, biofilters (BFs) are employed for their treatment, with the potential enhancement of mass transfer through the addition of surfactants. However, disparate results in previous studies have been observed, attributed to uncontrolled conditions during the introduction of surfactants to BFs. Additionally, there has been limited exploration of microbial consortium adaptation to surfactants. To address these gaps, this study followed two approaches. First, the long-term (247 days) removal of cyclohexane was studied in a stirred tank bioreactor (STBR) inoculated with Rhodococcus erythropolys E1 and using Tween 80 at three times the critical micelle concentration (CMC). Second, the short-term (9 days) impact of two (bio)surfactants [Tween 80 (1 × CMC) and Quillaja Saponin (QS, 1 × CMC)] on the removal of cyclohexane, hexane and toluene was investigated in batch tests using three types of inocula: a pure culture of Rhodococcus erythropolys E1 (X0), a microbial consortium adapted to cyclohexane (X1), and a microbial consortium adapted to cyclohexane with Tween 80 (X2). For long-term operation, the addition of Tween 80 at 3 × CMC improved cyclohexane removal efficiency (RE) to 87 ± 1% (elimination capacity, EC = 145 ± 25 mg m−3 h−1, gas residence time, GRT = 20 min, inlet concentration, Cin = 14.9 ± 2.5 ppmv), compared to a RE of 32 ± 9% (EC = 44 ± 8 mg m−3 h−1, GRT = 20 min, Cin = 15.1 ± 0.7 ppmv) under similar conditions without surfactants. For short-term operation, the addition of QS at 1 × CMC significantly increased biomass growth, resulting in lower maximum specific consumption rates for X1 and X2 compared to scenarios without surfactants or 1 × CMC Tween 80. The most abundant genera in X1 and X2 were Paludisphaera (26-23%), 67-14 genus (17–23%), and Rhodococcus (9–18%), respectively.

Numerical simulation of an unsteady ternary hybrid nanofluid along a convectively heated curved stretching sheet: A Tiwari-Das model

Nanofluids are smart fluids, which are very useful for heat and mass transfer enhancement. They are very much used in industrial, transportation, biomedical, and electronics fields. In the present research, we examine the nanofluid flow across a curved stretching sheet (CSS). Also, this work’s noteworthy originality is its discussion of the impacts of the physical parameters on the ternary hybrid nanofluid flow and heat transfer. Furthermore, the simulation considers nanofluids with water as the base fluid. The Koo–Kleinstreuer–Li (KKL) model examines the viscosity and effective thermal conductivity of fluid flow with suspended nanoparticles. The governing equations of the momentum and the temperature are transformed into ordinary differential equations (ODEs) by similarity transformations. These equations are then solved using a Secant iteration method combined with a Runge–Kutta–Fehlberg (RKF) integration scheme with a shooting technique. Through graphs and tables, the influences of the relevant non-dimensional parameters are presented and analyzed. The findings show that an increase in the curvature parameter and the Biot number is to increase the temperature gradient. The Streamline profiles for various values of the magnetic parameter are also analyzed through figures. We believe that this research has significant implications in biomedical devices and pharmaceutical fluid preparation in biomedical sciences. Some of them are high temperature and cooling processes, paints, space technology, medicines, cosmetics, conductive coatings, bio-sensors, and to name a few.

Microenvironment modulation of biocatalyst derived from natural cellulose of wheat straw for enhancing p-nitrophenol degradation via boosting peroxymonosulfate activation

Defect-rich nitrogen-doped biocatalyst (B-NC) was synthesized from natural cellulose of wheat straw using straightforward mechanical method and one-step pyrolysis approach. In contrast to the nitrogen-doped biocatalyst (NC), by leveraging the synergistic effects of nitrogen dopants and surface defects, the microenvironment-modulated B-NC exhibited the enhanced mass transfer efficiency and a significant improvement in reactivity for p-nitrophenol degradation (111 %–196 %). The catalyst's exceptional performance primarily arose from graphitic N, pyridinic N and CO active sites, which mainly derived from the cellulose structure of wheat straw and nitrogen dopants. Electron paramagnetic resonance and quenching tests confirmed that the B-NC/peroxymonosulfate system generated more reactive species (SO4•−, •OH, O2•−, and 1O2) during p-nitrophenol degradation, surpassing the NC/peroxymonosulfate system. Additionally, both density functional theory calculations and electrochemical experiments provided evidence of peroxymonosulfate strongly adsorbing onto B-NC's defect sites, facilitating the formation of catalyst/peroxymonosulfate* complexes and promoting electron transfer processes. This research provides valuable insights into the regulation of defects in nitrogen-doped biocatalyst derived from natural cellulose, presenting a promising solution for remediating refractory organic pollutants.

Sonication-Assisted Electrochemical Synthesis of Silver Nanoparticles.

In this work, we propose a method for synthesizing silver nanoparticles (Ag NPs) utilizing a sonication-assisted electrochemical approach with a common ultrasonic cleaner. Silver nitrate is employed as the precursor and polyvinylpyrrolidone functions as the ligand. The incorporation of sonication is identified as crucial for achieving several benefits such as enhanced mass transfer, improved dispersion of reactants, and the prevention of electrode fouling. Optimized sonication and electrochemical conditions synergistically contribute to a higher yield of well-dispersed Ag NPs, which are characterized by an average size of 10 nm. Furthermore, the electrode's suitability for the continuous synthesis of Ag NPs over an extended period is highlighted owing to effective electrode surface cleaning facilitated by sonication. This cleaning process proves to be essential in maintaining the electrochemical activity of the electrode, ensuring consistency in the synthesis process. The proposed sonication-assisted electrochemical synthesis method not only addresses challenges associated with electrode fouling but also significantly enhances the dispersity and yield of the resulting particles, making it valuable for scalability and practical applications in various fields, including sensors, catalysis, and nanotechnology.

Bubble characteristics in a novel microbubble gas-liquid-solid fluidized bed

The bubble characteristics are critical in gas-liquid-solid fluidized beds and microbubbles significantly enhance mass transfer in multiphase systems. In this work, a novel concept of microbubble gas-liquid-solid fluidized bed is proposed. Telecentric camera is employed to measure and analyze the microbubble characteristics including bubble size and gas holdup in this three-phase fluidized bed. Additionally, solid holdups in the fluidized bed are also examined. The results demonstrate that the bubble size adheres a lognormal distribution and is significantly influenced by superficial gas velocity. Bubble diameter exhibit a relatively uniform distribution in the radial direction. Bubbles exceeding than 1 mm substantially affect local gas holdup, and the microbubble flow promotes a more uniform distribution of local gas holdup in radial position. The average gas holdup deviation is less than 15 % compared to overall gas holdup obtained from pressure drop. Although microbubbles are more abundant, larger bubbles (> 1 mm) contribute more to solid particle fluidization. This paper introduces a methodology for assessing smaller-sized microbubbles in three-phase flow. The hydrodynamic analysis of the microbubble gas-liquid-solid fluidized bed establishes a foundational framework for enhancing gas-liquid mass transfer in fluidized bed.

Towards enhanced elevated-temperature mechanical properties by regulation of eutectic structure in Al-Cu-Si alloys solidified under super-gravity field

High volume fraction of tri-phase eutectic structure is challenging to obtain in ternary alloys through conventional methods. Currently, we reported that super-gravity solidification can be utilized to obtain high-volume fraction Al-Al2Cu-Si tri-phase eutectic structure in Al-Cu-Si alloys. The refinement of the eutectic structure can be detected mainly due to the enhancement of mass transfer, affecting the nucleation rate and growth of eutectic phase in the Al-Cu-Si eutectic system. Interestingly, the refined Al2Cu and Si eutectic structures are stable even up to 300 °C thermal exposure without obvious coarsening, contributing to the enhancement of elevated-temperature mechanical properties (∼268.8±8.8 MPa at 300 °C), which is ∼51.9 % higher than those solidified under normal gravity field (∼177.0±1.9 MPa). The refinement and homogeneous distribution of more Al-Al2Cu-Si tri-phase eutectic structures provide better stress dispersion, favoring crack initiation and propagation within the tri-phase eutectics, resulting in a transition from brittle fracture to ductile fracture mode.