Mass Transport Characteristics Research Articles

Advances in proton exchange membranes in polyelectrolytefuel cells

<p indent="0mm">Polyelectrolyte fuel cells (PEFCs) are promising devices for clean power generation in automotive, stationary, and portable applications. As a transition, the proton exchange membrane (PEM) is one of the important components in PEFCs, always promotes H⁺ ion transport, isolates the reaction gas (H₂ and O₂), and prevents electronic transmission between cathodes and anodes. Therefore, the performance of PEMs will directly affect the efficiency and stability of PEFCs, and the PEM with excellent performance is of great significance to PEFCs. Generally, PEMs should have extremely low gas permeability, high ion conductivity, fast water transmission and electrical insulation. To achieve this goal, PEM materials usually consist of three parts: Main chains, fixed groups, and ion exchange groups. Ion exchange groups provide faster ion transmission, while main chains and fixed groups endow PEMs with excellent chemical and mechanical stability for more stable mass transport in proton exchange membrane fuel cells (PEMFCs). Nowadays, due to better microphase separation (ordered arrangement between hydrophobic backbones and hydrophilic side chains), perfluorosulfonic acid (PFSA) membranes are the most widely used and commercialized PEMs. Moreover, to reduce the cost of PEMs, fluorine-containing PEMs and non-fluorine PEMs have been well developed. Specifically, the fluorine-containing PEMs with better microphase separation, fabricated by Suzuki-Miyaura coupling reactions or superacid catalysis methods, can provide high H⁺ conductivity and low cost. Surprisingly, some research has broken through the original H⁺ ion transport mechanism (Vehicular and Grotthuss mechanisms) and effectively improved the H⁺ ion transport rate by the modification of ion channels, such as polyrotaxane prepared via host-guest interactions, COFs-PEMs and PIMs-PEMs. This review mainly summarizes the research advances in PEMs in the past two decades. It starts from the principle of PEFCs and the important role of PEMs in PEFCs. The structural characteristics and mass transport characteristics of PEMs are then investigated while emphasizing the influence of molecular structures on the performance of PEFCs, mainly including PFSAPEMs, fluorine-containing PEMs and non-fluorine PEMs, as well as the recently developed new generation PEMs (polyrotaxane, COFs-PEMs and PIMs-PEMs). Meanwhile, the development and challenges of high-temperature proton exchange membranes (HT-PEMs) are introduced. HT-PEMs can effectively extend the operating temperature range of PEMFCs. HT-PEMFCs have attracted more attention due to several advantages, including improved electrode reaction kinetics, enhanced tolerance to fuel/air impurities, simple plate design, and better heat/water management. These advantages may mean the potential for using low Pt metal loading or even Pt metal free catalysts. Finally, according to the study of PEMs in recent years, this review looks forward to and predicts the direction of low-cost, high-performance PEMs in future. Up to now, although PEMs have been well developed, some performances are still not enough for the harsh environment during fuel cell operation, such as poor resistance to free radical, trade-off effects between cost and performance, and so on. Therefore, the development of PEMs should not only improve the H⁺ ionic conductivity, but also enhance the synergy between PEMs and other components in PEMFCs. Future research should focus on the performance of PEMs in the actual operating environment of PEMFCs.

Eulerian and Lagrangian transport by shallow-water breaking waves

This study examines the mass and Lagrangian transport, kinematic and dynamic characteristics of shallow-water breaking waves, focusing on the wave breaking, and jet impingement processes. A multiphase Navier–Stokes flow model has been developed to track the origin and trajectory for the jet and the splash-up using both a geometric piece-wise linear interface calculation volume-of-fluid (PLIC-VOF) and the Lagrangian particle tracking approaches. The model is first validated both quantitatively and qualitatively against the experimental data for the plunging jet and the splash-up during wave breaking, in which a good agreement is obtained. The mass transport and the origin of the jet and splash-up are studied using the new multi-component PLIC-VOF approach, and the different regions in the interior of the wave are tracked in an Eulerian way. Both horizontal and vertical drifts for the interior and surface particles are shown using the Lagrangian particles. The location and origin of the plunging jet can be clearly seen from the simulations. Various wave steepness and beach slopes have been investigated for different types of breakers. Furthermore, the detailed jet impingement, velocity, pressure, vorticity, and turbulence fields during wave breaking are discussed and presented, providing more detailed flow fields to gain further insight into the plunging jet and splash-up in shallow-water breaking waves.

Non-Uniform Porous Structures and Cycling Control for Optimized Fixed-Bed Solar Thermochemical Water Splitting

Abstract Solar thermochemical redox cycles provide a sustainable pathway for solar fuel processing. If done in porous (ceria) structures, they can profit from faster reaction rates owed to the enhanced heat and mass transport characteristics. However, the exact porous structure and operating conditions significantly affect the performance. We present a transient volume-averaged fixed-bed model of a thermochemical redox reactor utilizing macroporous ceria. We studied the porosity-dependent (ɛ = 0.4–0.9) and operating condition-dependent (solar concentration ratio, ratio of oxygen partial pressure to total pressure, and gas flowrate) performance of the fixed-bed ceria redox cycle. Structures with large porosity (ɛ = 0.9) showed better performance than low-porosity structures, owning to the enhanced heat absorption and resulting higher temperatures. We show that the cycle duration requires optimization according to the porosity of the structure. Two hours of operation for a structure with ɛ = 0.75 resulted in the largest hydrogen production (115.78mLgceria−1) if the single cycle duration was 240 s (i.e., 30 cycles in 2 h), while nearly five times less was produced for a 15 times longer single cycle duration (i.e., two cycles in 2 h). We subsequently introduced porous structures with different types of non-uniform porosity distributions. For an average porosity of ɛ = 0.75, the most favorable non-uniform porosity media exhibited higher porosity at the boundaries and a denser core. The fuel production of the best non-uniform porous structure was six times larger compared to a uniform porous structure. Adjusting on top of this the cycling conditions, a 14.6 times production gain was achieved. This work suggests that under non-isothermal operation condition for macroporous ceria redox fixed-bed cycling, non-uniform porous structure with higher porosity boundaries and a dense core benefit fuel production and porosity-dependent cycle duration modulation can be used to increase performance.

Analysis of heat and mass transport characteristics in microchannel reactors with non-uniform catalyst distributions for hydrogen production

PurposeThe purpose of this paper is to investigate the heat and mass transport characteristics in microchannel reactors with non-uniform catalyst distributions.Design/methodology/approachA two-dimensional model is developed to study the heat and mass transport characteristics in microchannel reactors. The heat and mass transport processes in the microchannel reactors with non-uniform catalyst distribution in the catalytic combustion channel are also studied.FindingsThe simulated results are compared in terms of the distributions of species mole fraction, temperature and reaction rate for the conventional and new designed reactors. It is found that the chemical reaction, heat and mass transport processes are significantly affected and the maximum temperature in the reactor is also greatly reduced when a non-uniform catalyst distribution is applied in the combustion catalyst layer.Practical implicationsThis study can improve the understanding of the transportation characteristics in microchannel reactors with non-uniform catalyst distributions and provide guidance for the design of microchannel reactors.Originality/valueThe design of microchannel reactors with non-uniform catalyst distributions can be used in methane steam reforming to reduce the maximum temperature inside the reactor.

Gastight rotating cylinder electrode: Toward decoupling mass transport and intrinsic kinetics in electrocatalysis

AbstractDecoupling and understanding the various mass, charge, and heat transport phenomena involved in the electrocatalytic transformation of small molecules (i.e., CO2, CO, H2, N2, NH3, O2, and CH4) is challenging but it can be readily achieved using dimensionless quantities (i.e., Reynolds, Sherwood, Schmidt, Damköhler, Nusselt, Prandtl, and Peclet Numbers) to simplify the characterization of systems with multiple interacting physical phenomena. Herein we report the development of a gastight rotating cylinder electrode cell with well‐defined mass transport characteristics that can be applied to experimentally decouple mass transfer effects from intrinsic kinetics in electrocatalytic systems. The gastight rotating cylinder electrode cell enables the dimensionless analysis of electrocatalytic systems and should enable the rigorous research and development of electrocatalytic technologies.

Pore-scale modeling of mass transport in the air-breathing cathode of membraneless microfluidic fuel cells

The air-breathing cathode of membraneless microfluidic fuel cells (MMFCs) is in direct contact with flowing aqueous electrolyte rather than a solid polymer membrane, suggesting the mass transport characteristics can be different from the air-cathode in conventional membrane-based fuel cells. To investigate the mass transfer and reaction, pore-scale Lattice Boltzmann (LB) models were developed for the air-breathing cathode, including the gas diffusion layer (GDL), the catalyst layer and the electrolyte microchannel. A modified multi-relaxation-time LB model was developed to handle the very large diffusivity ratio (104) between gaseous and dissolved oxygen. The GDLs were numerically reconstructed to mimic the real microstructure. The effect of GDL property (porosity, isotropy) and operation conditions (overpotential, electrolyte flow rate) were investigated and discussed. The results indicated that the GDL microstructure played an important role for the oxygen transport and reaction in the air-breathing cathode. Oxygen was found to penetrate the electrolyte microchannel and could form a thin layer of dissolved oxygen covering the catalyst layer, which in-turn affected oxygen transfer in the GDL. The electrolyte flow can also affect local oxygen transport but only showed minimum impacts.

Impact of Swimming Gyrotactic Microorganisms and Viscous Dissipation on Nanoparticles Flow through a Permeable Medium: A Numerical Assessment

In this paper, heat and mass transportation flow of swimming gyrotactic microorganisms (microbes) and solid nanoparticles under the viscous dissipation effect is investigated. The flow model PDEs are renovated with ordinary ones using suitable boundary layer approximations. The system governing the flow model dimensionless equations as well as boundary conditions is numerically treated with the SOR (successive over relaxation) technique. The flow, heat, and mass transport characteristics are examined against the prime parameters. A comparison is examined to be in a good agreement with the earlier results. It is found here that flow and thermal characteristics of the problem are substantially affected by the porous medium. The outcomes evidently point out that porous medium causes an enhancement in the skin friction and density of the motile microbes. Further, the rate of heat transport is devaluated at the surface of sheet due to viscous dissipation and elevated due to suction.

Study on mass transfer performance and membrane resistance in concentration of high salinity solutions by electrodialysis

• Effects of various parameters on mass transport and membrane resistance were studied. • A simplified model was developed to describe mass transport and membrane resistance. • Counter flow electrodialysis may not be superior to parallel flow electrodialysis. • Membrane resistance increased dramatically at an extremely high salt concentration. • Appropriate concentration ranges were suggested for electrodialysis concentration. There is a growing demand for efficient and economical concentration of high salinity solutions, either to recover valuable salts from non-traditional sources or to reduce the environmental impact of brines from desalination plants. Electrodialysis is one of the most promising technologies for treating high salinity solutions with outstanding performance and energy conservation potential. This paper demonstrated the overall performance of mass transport and membrane resistance in electrodialysis for concentrating several high salinity solutions. The effects of various parameters on mass transfer performance and membrane resistance were examined. A simplified mathematical model for the characterization of mass transport and membrane resistance was developed. The initial concentration was found to play a dominant role in the salt transport and hydration number, whereas the current density, volume ratio and flow rate were negligible. A higher volume ratio and greater current density contributed to a greater maximum achievable concentration. In addition, the counter flow electrodialysis did not perform better than the parallel flow electrodialysis in experiments, likely caused by a non-uniform difference in pressure between the concentrated and diluted compartments. The initial concentration was also found to have a significant effect on the membrane resistance, which increased dramatically at an extremely high salt concentration probably due to the membrane shrinkage. Depending on the salt transport number, extractable water content and membrane resistance, appropriate concentration ranges of several high salinity solutions were suggested for electrodialysis concentration and desalination.

Topological design, mechanical responses and mass transport characteristics of high strength-high permeability TPMS-based scaffolds

A strategy of controlling the topology structure of triply periodic minimal surface (TPMS)-based scaffolds (CTTS) was proposed in this study to cater to the mechanical and biological requirements. Two new types of TPMS-based scaffolds called AD and AG were designed on the basis of diamond (ID) and gyroid (IG). The topology structures of ID and IG were changed by manipulating the trigonometric functions in the expressions. AD and AG retained the advantageous structural characteristics of ID and IG, such as high wall surface area and good connectivity. However, they differed in terms of pore shape and size. The gradient density ID (FD) and the gradient density IG (FG) were designed for comparison. The porosities of ID, IG, FD, FG, AD, and AG were set to 60, 70, and 80%. Compressive simulations and computational fluid dynamics simulations were conducted for the designed scaffolds. AD with 80% porosity (AD80) and FD with 80% porosity (FD80) were manufactured through electron beam melting. Their morphological features were characterized through microcomputer tomography scanning and scanning electron microscopy. Compression and fall head tests of AD80 and FD80 were performed. In combination with the numerical results, the geometrical parameters, manufacturing accuracies, mechanical properties, permeability, and flow behavior of each scaffold were systematically analyzed. Results show that with the same porosity, the manufacturing accuracies and the permeability of AD and AG are higher than ID, IG, FD, and FG. The mechanical properties of AD are higher than other scaffolds. Although the wall surface area of AD is smaller than ID and FD, it is still larger than IG and FG, which can provide sufficient space for cell adhesion. AD is an appropriate candidate for solving the contradiction between sufficient mechanical properties and high permeability and exhibits excellent biological property.

Effect of Pt Loading Percentage on Carbon Blacks with Large Interior Nanopore Volume on the Performance and Durability of Polymer Electrolyte Fuel Cells

Achieving high performance and durability at low Pt loads is an important challenge for polymer electrolyte fuel cells (PEFCs). We investigated the effect of catalyst Pt loading percentage (wt % Pt) on the performance and durability of an ultrahigh surface area carbon black (CB) with a large nanopore volume using morphological observations, nitrogen adsorption, and electrochemical performance measurements. The ratio of the surface areas of Pt on the interior and exterior surfaces of the CB affects the penetration of the ionomer into the nanosized pores. When the exterior Pt surface area is larger than that of the interior, the oxygen diffusion resistance in the ionomer increases and the performance deteriorates due to the thick covering of the ionomer on the exterior Pt. Based on durability testing that combines startup, shutdown, and galvanostatic load cycling, the main deterioration factors are dependent upon the Pt interparticle distance and the thickness of the catalyst layer, which vary with the wt % Pt. The advanced characterization and optimization of the various wt % Pt on an ultrahigh surface area CB, combined with the extensive performance and durability testing, have provided an unprecedented understanding of the reaction sites, mass transport characteristics, and stability, which are crucial for their practical application in PEFCs.

Rheological and mass transport characteristics of hydrocolloid incorporated multilayered wheat flour dough sheet (Khaja) during frying

The purpose of this study was to analyze the effect of the addition of hydrocolloids such as gum arabic and xanthan gum, as well as a mixture of gum arabic and xanthan gum on moisture and oil transport properties in deep fat-fried multilayered wheat flour dough sheet (Khaja). The dynamic viscoelastic analysis of the dough showed that the hydrocolloid incorporated sample had a larger difference in the storage and loss modulus values, indicating that hydrocolloids had a synergistic effect on increasing the elastic property of the dough. The multilayered wheat flour dough sheet was deep fat-fried in a fryer at a frying oil temperature of 180°C. Hydrocolloid inclusion reduced the moisture diffusivity of the product, and the moisture diffusivity of the hydrocolloid incorporated sample decreased from 4.60 × 10−9 to 3.32 × 10−9 m2/s. The sample containing the combination of gum arabic and xanthan gum reduces oil absorption by 20.13% compared to the control sample. Novelty impact statement Oil absorption in Khaja is influenced by the type of hydrocolloid, moisture content of the dough, frying duration, and temperature of frying. Hydrocolloid significantly affected the viscoelastic characteristics of the dough and reduced the hardness of the product. The dough containing a combination of xanthan gum and gum Arabic decreased oil absorption by around 20% in Khaja.

Robust optimization in nanoparticle technology: A proof of principle by quantum dot growth in a residence time reactor

Knowledge-based determination of the best-possible experimental setups for nanoparticle design is highly challenging. Additionally, such processes are accompanied by noticeable uncertainties. Therefore, protection against those is needed. Robust optimization helps determining optimal processes. The latter guarantees quality requirements regardless of how uncertainties e.g., in raw materials, particle size distributions (PSD), heat and mass transport characteristics, and (growth) rates, manifest within predefined ranges. To approach this task, we exemplarily model a particle synthesis process with seeded growth by population balance equations and study different growth kinetics. We determine the mean residence time maximizing the product mass subject to a guaranteed yield. Additionally, we hedge against uncertain growth rates and derive an algorithmically tractable reformulation for the robustified problem. This reformulation can be applied if both the objective and the constraint functions are quasiconcave in the uncertainty which is a natural assumption in this context. We also show that the approach extends to higher-dimensional uncertainties if the uncertain parameters do not influence each other. We evaluate our approach for seeded growth synthesis of zinc oxide quantum dots and demonstrate computationally that a guaranteed yield is met for all growth rates within predefined regions. The protection against uncertainties only reduces the maximum amount of product that can be obtained by a negligible margin.

Analytical simulation of time dependent electromagneto-hydrodynamic flow of Williamson fluid due to oscillatory curved convectively heated Riga surface with variable thermal conductivity and diffusivity

The main objective of the present article is to provide an analytical simulation for time dependent boundary layer flow of non-Newtonian Williamson fluid due to stretchable curved oscillatory Riga surface. Also the characteristics of heat and mass transport are studied under the influence of variable thermal conductivity and diffusivity along with convective heat and mass boundary conditions. Additionally, energy equation is also characterized with the impact of heat production. Curvilinear coordinate scheme is followed to attain the boundary layer expressions for the flow model. The governing nonlinear partial differential equations are solved analytically via homotopy analysis method (HAM). Graphs are plotted to examine comprehensively the consequences of various concerned parameters like modified magnetic parameter and radius of curvature, Williamson fluid parameter, relation of the surface's oscillating frequency to its stretching rate constant, Prandtl number, variable conductivity and heat production parameters, Schmidt number and variable diffusivity parameter on concentration, temperature, pressure and velocity profile. Also the outcomes of afore said variables on surface drag force, rate of temperature and mass transmission (Nusselt and Sherwood numbers) are shown in tabular form. The liquid velocity amplitude is enhanced with modified magnetic parameter and shows opposite behavior for Williamson fluid parameter.

Simulation study on real laminar assembly of g-C3N4 high performance free standing membrane with bio-based materials

The complex transport mechanism of water and ions in the membrane hinders the design of free standing membranes. The mechanism of the mass transport characteristics of traditional nanofiltration membranes is no longer applicable to free standing membranes due to the change of the driving force in the membrane. In this study, the vacuum filtration of the g-C3N4 suspension was simulated to form a free standing membrane model for the first time by using the molecular dynamics (MD) simulations. In the nanochannels formed by the g-C3N4 nanosheets, the water molecules rapidly penetrated across the free standing membrane due to ultra-low friction. On the other hand, the hydrated Na+ and Mg2+ ions needed energy to partially dehydrate and penetrate across the free standing membrane. Moreover, the MD simulations indicated that the speed of Mg2+ ions penetrating across the g-C3N4 nanochannels was lower than that of Na+ ions. Combined with the computational works, salt retention experiments were conducted to demonstrate the correctness of the proposed model. Further, the developed membranes exhibited excellent non-swelling stability and antibacterial activity in aqueous solutions. The g-C3N4 free standing membranes prepared in this study can effectively realize the separation of monovalent and divalent ions, accompanied with high permeability.

Numerical investigation on magnetohydrodynamics boundary layer flow of micropolar Carreau nanofluid with nonlinear thermal radiation

The current work examines the behaviour of micropolar Carreau nanofluid flow past an infinite vertical plate with nonlinear thermal radiation. Magnetic field, heat source/sink, viscous dissipation, internal and Joule heating effects are considered. The governing equations are reframed and expressed in the non-dimensional form with appropriate dimensionless quantities to analyse the model. The nonlinear non-dimensional governing equations are solved numerically using finite difference approximation to acquire the solutions. Impact of involving flow controlling parameters on fluid flow, heat and mass transport characteristics are discussed and presented via tables and graphical illustrations. Our outcomes figured out that the fluid motion and angular velocity declines with greater magnetic parameter values, and reverse trend is observed for micropolar constant. Further, computational results depict that thermal distribution is a rising function of radiation parameter and high thermal performance is observed; that is, 10.45% more temperature distribution is noticed in presence of nonlinear thermal radiation.

Cathodic generation of hydrogen peroxide sustained by electrolytic O2 in a rotating cylinder electrode (RCE) reactor

This investigation reports the electrosynthesis of H2O2 from the two-electron reduction of dissolved O2, provided by anodic water oxidation, in a rotating cylinder electrode (RCE) reactor. O2 evolved at six surrounding Ti|IrO2 anode plates, whereas the oxygen reduction reaction (ORR) occurred at a (C-PTFE)-coated carbon cloth covering a rotating steel cathode. The mass transport characterization of the cathodic ORR to yield H2O2 was carried out through limiting current measurements (-0.65 ≤ E ≤ -0.3 V vs. SHE). Peripheral velocities (U) between 11.9 and 79.6 cm s−1 (i.e., Reynolds (Re) numbers of 4537 ≤ Re ≤ 30243) were employed to ensure turbulent flow conditions. An apparent plateau was obtained in the studied potential range, in agreement with mass transport-controlled ORR. From the limiting current values obtained, the mass transport correlation kma=bUc, which describe the transport considering the geometrical aspects of the cell and the hydrodynamic regime, were obtained. Additionally, bulk electrolyses were executed to accumulate H2O2, with no O2 feeding from any air pump. These trials were performed under mass transport control at a cathode potential of -0.46 V vs. SHE. Both, mass transport studies and bulk H2O2 electrogeneration, were performed in the presence and absence of atmospheric air on top of the RCE reactor to evaluate the potential contribution of additional O2 dissolution promoted by the electrolyte velocity and pressure gradients imposed by the RCE. Its contribution to H2O2 production depended on U. The best conditions for the self-sustained electrolytic H2O2 synthesis were U = 79.6 cm s−1 and cathode potential of -0.46 V, achieving 177.2 mg L−1 H2O2 with current efficiency and energy consumption of 23.3% and 0.013 kW h (g H2O2)−1 after 180 min. The potential application of this RCE reactor to the degradation of organic pollutants is thus envisaged.

Correlation between impedance spectroscopy and bubble-induced mass transport in the electrochemical reduction of carbon dioxide

In the electrochemical conversion of carbon dioxide, high currents need to be employed to obtain large production rates, thus implying that mass transport of reactants and products is of crucial importance. This aspect can be investigated by employing a model that depicts the local environment for the reduction reactions. Simultaneously, electrochemical impedance spectroscopy, despite being a versatile technique, has rarely been adopted for studying the mass transport features during the carbon dioxide (CO2) electroreduction. In this work, this aspect is deeply analyzed by correlating the results of impedance spectroscopy characterization with those obtained by a bubble-induced mass transport modeling under controlled diffusion conditions on a gold rotating disk electrode. The effects of potential and rotation rate on the local environment are also clarified. In particular, it has been found that CO2 depletion occurs at high kinetics when the rotation is absent, giving rise to an increment of the competing hydrogen evolution reaction. This feature reflects in an enlargement of the diffusion resistance, which overcomes the charge transport one.

Electrochemical vanillin reduction in a plane parallel flow reactor: Characterization, modeling and process improvement

The application of electrochemical flow reactors for electrosynthetic processes on a laboratory or pilot scale has recently gained increased attention as they provide reliable and improved performance and facilitate a further scale-up. We investigated in this study the electrochemical reduction of vanillin (4-hydroxy-3-methoxybenzaldehyde) to its pinacolization product hydrovanilloin, a building block in the synthesis of biobased polymers, in a divided plane parallel flow reactor in batch recycle operation mode. First, the mass transport of the flow reactor was characterized with dimensionless groups using the ferricyanide ion / ferrocyanide ion system as model reaction. The mass transport was further improved by 3D-printed turbulence promoters. We then studied the electrochemical vanillin reduction monitored by an online UV-cell setup at various electrolyte flow rates up to 20 cm s−1 and current densities up to 50 mA cm−2 with total conversions of 95%. Key figures of merit such as Faradaic efficiencies, space-time-yields and specific energy consumptions were calculated and a simple model was used to describe vanillin concentration decays and courses of these key figures of merit. The model distinguishes between a kinetic and mass transport-controlled zone, which transition point was predicted based on the mass transport characterization results. Lastly, we developed based on the model an operational process improvement strategy for fast and energy efficient production of hydrovanilloin and validated it experimentally. This study reports a first engineering approach for the production of vanillin-based polymer building blocks in an electrochemical flow reactor highlighting the ability of simple prediction models.

Numerical simulation for heat and mass transport analysis for magnetic-nanofluids flow through stretchable convergent/divergent channels

This paper adopts a theoretical approach to explore the heat and mass transport features for MHD Jeffery–Hamel flow of viscous nanofluids through convergent/divergent channels with stretching or shrinking walls. Recently, this type of flows generated by nonparallel inclined plates with converging or diverging properties has been frequently utilized in various industrial and engineering processes, like, blood flow through arteries, different cavity flows and flow through canals. The current flow model is formulated mathematically in terms of partial differential equations (PDEs) in accordance with conservation laws under an assumption that the flow is symmetric and purely radial. In addition, heat and mass transport mechanisms are being modeled in the presence of Brownian motion and thermophoretic aspects using Buongiorno’s nanofluid model. The dimensionless variables are employed to get the non-dimensional forms of the governing PDEs. The built-in MATLAB routine bvpc4 is implemented to determine the numerical solutions for governing the nonlinear system of ordinary differential equations (ODEs). Numerical results are presented in the form of velocity, temperature and concentration plots to visualize the influence of active flow parameters. The simulated results revealed that the Reynold number has an opposite effect on dimensionless velocity profiles in the case of convergent and divergent channels. Besides, the temperature distributions enhance for higher values of Brownian motion parameter.

Opus 12's CO2 transformation and the importance of collaboration

Opus 12's CO2 transformation and the importance of collaboration