Liquid-phase Transport Research Articles

Study of the efficiency of sodium silicate water softening processes

The current state of natural water resourses requires preliminary softening for almost all drinking waters and waters for energy purposes. Therefore, the search for effective softening technologies and reagents is especially relevant today. Researches in this field are constantly increasing every year due the intensive quality deterioration of the natural waters. The processes of calcium and magnesium ions removing from water are on central place in such researches. It is traditionally considered that magnesium ions are more difficult to remove from water than calcium ions because magnesium ions form less quantity of insoluble compounds. The total efficiency of water softening processes depends on the residual content of both cations. Therefore, researchers also pay a lot of attention to magnesium ions removing. Sodium hydroxide and sodium phosphate are considered as a perspective reagents in such processes. However, the use of first reagent is associated with a significant increase of pH index, and the use of second reagent requires a big quantity of the reagent and needs the alkaline medium for sufficient efficiency. Therefore, in this work, we investigated the effectiveness of sodium silicate in the processes of magnesium and calcium ions removing from the aqueous medium. A characteristic feature of the solid phase formation in reaction between magnesium cations and silicate anions is the significant reaction dependence on the pH index. In neutral environment, the formation of a solid phase in model solutions was not visually fixed. However, some decrease of water hardness after filtering through "blue tape" filter paper is still observed. And it is decrease with increasing of pH index. The most effective softening process can be obtained at pH levels > 10. It was not possible to obtain any positive results during study of settling and filtering processes of the formed solid phase. At the same time, the ratio between the components and the initial water hardness does not affect the clarification process practically. However, sodium silicate can be quite effective in stoichiometric or higher ratios. But a significant disadvantage of such method is a pH index increasing when the components are mixed. It requires futher adjusting the pH level in the treated water. And this is aditional stage of water treatment. It was not possible to obtain positive results when aluminum hydroxide was used as a settling and filtering intensifier. With the ratio K = [SiO32-, mg-eq]/[Mg2+, mg-eq] = 1 and different doses of aluminum ions, there is no significant intensification of sedimentation processes in the range of aluminum ions doses from 10 to 70 mg/dm3. And with aluminum doses less than 30 mg/dm3, there is even inhibition of the settling process. Like in the case of sodium silicate silicate treatment of magnesium containing solutions, the precipitation of calcium silicate strongly depends on the pH level. High efficiency of process is observed only in a highly alkaline environment. Under other conditions, the softening efficiency is significantly reduced. With an excess or lack of a precipitant, more compact particles are formed. The settling process for such particles occur more faster. At the same time, for a stoichiometric or near ratio between the components, particles of the branched structure are formed. Such particles settle twice slowly and occupy a larger imaginary volume. With a stoichiometric ratio of components, the speed is significantly slowed down, and when K = [SiO32-, mg-eq]/[Ca2+, mg-eq] ≥ 1,0 all filter pores are blocked during the first 10 min and liquid phase transportation stops. Reducing the initial water hardness to 20 mg-eq/dm3 does not significantly change the situation. Clarification of the suspension occurs partially. A significant amount of suspended particles remains in the mother solution. The flocculating ability of silicon compounds does not appeared under these conditions. When the content of calcium ions is reduced to 10,2 mg-eq/dm3, treatment with an equivalent amount of sodium silicate does not lead to a solid phase formation. Although after filtering through the "blue tape" filter the water hardness decreases. At the same time, the filtration properties of the solid phase formed during the softening process are the same as the filtration properties of carbonates, phosphates and hydroxides, so the reagent cannot be recommended for use in low- and medium-productivity systems, where the filtration is a main phase separation process.

Particle distribution and two-phase flow characteristics of twin-screw pump during solid-liquid transfer

The twin-screw pump is a kind of positive displacement machinery with smooth pressure and flow pulsation and strong self-priming ability, which is widely used in the fields of oilfield production, marine engineering, and other fields. However, in the process of conveying liquid-phase media, it is difficult to avoid the inclusion of solid impurities and grit, resulting in wear of the pump casing and rotor, and the pump’s pressurization capacity is reduced or even shut down. At present, the solid-liquid two-phase flow characteristics within the twin-screw pump have not been clarified, which hinders the study of particle wear in the pump. In this paper, a solid-liquid two-phase flow study is carried out on a twin-screw pump through numerical simulation and experimental testing. The distribution of particles with different diameters in the rotor domain with the liquid-phase transport process is explored by simulating the two-phase flow under different differential pressures and particle concentrations. The results show that the particles in the rotor domain are mainly distributed in the region away from the male and female rotor engagement, and the number of particles near the engagement is small but the velocity is higher under the influence of the clearance jets; the elevation of the differential pressure and the particle concentration increase the risk of the particles to collide with the rotor more frequently and at higher velocity; at different particle concentrations, new localized vortices are caused by particle conveying which compared to pure liquid transport, but there are also cases where the original vortices are suppressed. The results will provide a theoretical basis for further research on particle wear characteristics in twin-screw pumps.

Carbon sequestration in the subsoil and the time required to stabilize carbon for climate change mitigation.

Soils store large quantities of carbon in the subsoil (below 0.2 m depth) that is generally old and believed to be stabilized over centuries to millennia, which suggests that subsoil carbon sequestration (CS) can be used as a strategy for climate change mitigation. In this article, we review the main biophysical processes that contribute to carbon storage in subsoil and the main mathematical models used to represent these processes. Our guiding objective is to review whether a process understanding of soil carbon movement in the vertical profile can help us to assess carbon storage and persistence at timescales relevant for climate change mitigation. Bioturbation, liquid phase transport, belowground carbon inputs, mineral association, and microbial activity are the main processes contributing to the formation of soil carbon profiles, and these processes are represented in models using the diffusion-advection-reaction paradigm. Based on simulation examples and measurements from carbon and radiocarbon profiles across biomes, we found that advective and diffusive transport may only play a secondary role in the formation of soil carbon profiles. The difference between vertical root inputs and decomposition seems to play a primary role in determining the shape of carbon change with depth. Using the transit time of carbon to assess the timescales of carbon storage of new inputs, we show that only small quantities of new carbon inputs travel through the profile and can be stabilized for time horizons longer than 50 years, implying that activities that promote CS in the subsoil must take into consideration the very small quantities that can be stabilized in the long term.

Fabrication of core-shell Co@HCN@PANI composite material with enhanced electromagnetic wave absorption

A core-shell Co@ hollow carbon nanospheres @ polyaniline nanocomposite for EMW absorption was constructed via soft template, switching liquid phase transport and in-situ polymerization method. Polarization at the interface of Co, HCN shell and PANI enhances the polarization loss of core-shell Co@HCN@PANI nanocomposite. The dense conductive network formed by PANI endows the material with a more significant electronic conduction loss mechanism. Multi-layer heterogeneous interfaces in core-shell structures and multi-centers in PANI molecular chains enrich the polarization relaxation loss mechanism. The natural resonance of magnetic Co at high frequency bands and eddy current thermal effect at low frequency bands ensure the stable magnetic loss of the material. Good impedance matching and enhanced attenuation coefficient further improve the microwave absorption performance of the nanocomposite. Consequently, a minimum reflection loss of −43.63 dB and an effective absorption bandwidth of 9.75 GHz (8–17.75 GHz) are obtained at a matched thickness of 2.8 mm.

Investigating the Influence of Polymer Binders on Liquid Phase Transport and Tortuosity Through Lithium-Ion Electrodes

Quantifying the tortuosity of porous lithium-ion electrodes is important for understanding the rate capability of cells and for optimizing their design, particularly when designing high energy density cells such as those desired for electric vehicles. However, quantifying tortuosity may be difficult, and results often disagree with the commonly used Bruggeman relation. Here, we discuss the observation that PVDF binder, a polymer used to mechanically hold the electrode together, has a direct effect on the rate capability of NMC111 cathodes. Using a pseudo-two-dimensional (P2D) physics-based model of the system, we fit the electrode tortuosity to the cycling data and determine that increased binder volume fraction in an electrode leads to increased electrode tortuosity. Using a TiO2-based blocking electrode, we further support these findings using electrochemical impedance spectroscopy (EIS) measurements and transmission line models. Finally, using pulsed field gradient nuclear magnetic resonance (PFG-NMR) experiments on these blocking electrodes, we propose a mechanism involving liquid phase Li ion “choke-points,” formed by the addition of PVDF binder, which dominates electrode tortuosity. We provide an empirically derived relationship that serves as a binder volume correction to the Bruggeman relation, and this finding motivates further work on the impact of different electrode components on transport through porous electrodes.

Effects of oscillating gas-phase flow on an evaporating multicomponent droplet

The dynamics of an evaporating droplet in an unsteady flow is of practical interest in many industrial applications and natural processes. To investigate the transport and evaporation dynamics of such droplets, we present a numerical study of an isolated droplet in an oscillating gas-phase flow. The study uses a one-way coupled two-phase flow model to assess the effect of the amplitude and the frequency of a sinusoidal external flow field on the lifetime of a multicomponent droplet containing a non-volatile solute dissolved in a volatile solvent. The results show that the evaporation process becomes faster with an increase in the amplitude or the frequency of the gas-phase oscillation. The liquid-phase transport inside the droplet also is influenced by the unsteadiness of the external gas-phase flow. A scaling analysis based on the response of the droplet under the oscillating drag force is subsequently carried out to unify the observed evaporation dynamics in the simulations under various conditions. The analysis quantifies the enhancement in the droplet velocity and Reynolds number as a function of the gas-phase oscillation parameters and predicts the effects on the evaporation rate.

Direct Magnetic Evidence, Functionalization, and Low-Temperature Magneto-Electron Transport in Liquid-Phase Exfoliated FePS3.

Magnetism and the existence of magnetic order in a material is determined by its dimensionality. In this regard, the recent emergence of magnetic layered van der Waals (vdW) materials provides a wide playground to explore the exotic magnetism arising in the two-dimensional (2D) limit. The magnetism of 2D flakes, especially antiferromagnetic ones, however, cannot be easily probed by conventional magnetometry techniques, being often replaced by indirect methods like Raman spectroscopy. Here, we make use of an alternative approach to provide direct magnetic evidence of few-layer vdW materials, including antiferromagnets. We take advantage of a surfactant-free, liquid-phase exfoliation (LPE) method to obtain thousands of few-layer FePS3 flakes that can be quenched in a solvent and measured in a conventional SQUID magnetometer. We show a direct magnetic evidence of the antiferromagnetic transition in FePS3 few-layer flakes, concomitant with a clear reduction of the Néel temperature with the flake thickness, in contrast with previous Raman reports. The quality of the LPE FePS3 flakes allows the study of electron transport down to cryogenic temperatures. The significant through-flake conductance is sensitive to the antiferromagnetic order transition. Besides, an additional rich spectra of electron transport excitations, including secondary magnetic transitions and potentially magnon-phonon hybrid states, appear at low temperatures. Finally, we show that the LPE is additionally a good starting point for the mass covalent functionalization of 2D magnetic materials with functional molecules. This technique is extensible to any vdW magnetic family.

Influence of dispersive long-range interactions on transport and excess properties of simple mixtures

The influence of dispersive long-range interactions on liquid bulk phase transport and excess properties of six binary Lennard–Jones (LJ) mixtures was studied by molecular dynamics simulation and equation of state modelling. For the transport properties, the self-diffusion coefficients, mutual diffusion coefficients, shear viscosity, and thermal conductivity were considered. For the excess properties, the excess energy, volume, Gibbs energy, and entropy were studied. Moreover, the thermodynamic factor was studied. The two components had the same size parameter in all cases, but different dispersion energies and different cross-interaction parameters. Thereby, the six resulting mixtures show three types of phase behaviour: ideal, high- and low-boiling azeotrope. For studying the influence of the dispersive long-range interactions, the results of the full LJ potential were compared to the LJ truncated and shifted (LJTS) potential applying the corresponding states principle. The dispersive long-range interactions have a significant influence on the self-diffusion and the mutual diffusion coefficients, whereas the shear viscosity and the thermal conductivity are hardly affected. For all investigated properties, the dispersive long-range interactions have practically no influence on the composition dependency.

LOCAL THERMAL NON-EQUILIBRIUM CONDITION FOR THE FLOW OF WALTERS-B FLUID OVER A SHEET SATURATED IN A POROUS MEDIUM

Local thermal non-equilibrium (LTNE) has garnered significant interest in engineering applications like electronic cooling, heat pipes, nuclear reactors, drying technology, and multiphase catalytic reactors. Owing to this, the study numerically emphases on the LTNE effects on the flow of Walters-B liquid over a stretching sheet with Dufour and Soret effects. The LTNE model, which creates distinct thermal profiles for both solid and liquid phases, is utilized to formulate the energy equations, which constitutes the novelty of the present study. The governing equations for the flow assumptions are transformed to ordinary differential equations using the apt similarity transformations. The Runge-Kutta approach and the shooting technique are then used to numerically solve these reduced equations. The significant results of the current analysis are that an upsurge in Dufour number diminutions the heat transport in liquid phase. The increase in Soret number advances the mass transport. The augmented values of viscoelastic parameter drop down the velocity, but advance the fluid phase heat transference. Finally, the heat transport of the liquid phase increases and solid phase drops as inter-phase heat transfer parameter rises.

Wet Gas Water Feed of Polymer Electrolyte Membrane Electrolyzer for Simultaneous Hydrogenation of Organic Chemical Hydride Energy Carrier and Water Decomposition

To utilize renewable electricity with fluctuation and localization, large-scale energy storage and transportation technologies using hydrogen energy carrier have been expected. In order to improve hydrogen energy carrier synthesis, we have studied one-step electrolysis for toluene electrohydrogenation and water decomposition using proton exchange membrane (PEM) electrolysis. This process has 1.09 V of theoretical decomposition voltage for simultaneous water electrolysis and toluene hydrogenation.As shown in Figure 1, anode reaction produces oxygen and proton, and proton transports cathode electrocatalyst layer through the PEM with water molecular. Water inhibits toluene transportation to reaction side and hydrogen evolution occurs as side reaction. We have reported electrolyzers that has cathode side of PEFC’s MEA like structure using PtRu/C and anode side of industrial electrolyzer like structure using mesh shape of DSE® electrode for oxygen evolution reaction, and sulfuric acid solution feeds as anolyte that is not only reactant but also for water management. Water back diffusion from cathode to anode enhances with sulfuric acid concentration. In addition, current efficiency with mesh type anode was higher than that with sintered fiber sheet type anode. The mesh shape of electrode makes current distribution that affects mass transfer pass distribution to improve current efficiency, although sheet type anode is lower overpotential because of large surface area [1 – 3]. As practical system, water transportation from anode to cathode should be supressed without sulfuric acid utilization, and electrochemical surface- area of anode should extend to reduce overpotential.In this study, we have investigated wet gas water feed for PEM electrolysis to reduce water transfer to cathode, because water transfer would control by relative humidity of wet gas that feed to anode for oxygen evolution reaction. Here, PEM water electrolysis type anode catalyst layer with ionomer was employed to reduce anode overpotential and to maintain ionic conduction in catalyst layer.Figure 1 shows the schematic drawing of toluene direct hydrogenation electrolyzers with water splitting. Figure 1 (a) is our conventional electrolyzer of H2SO4 solution feed, and Figure 1 (b) is wet air feed in this study. The anode side for wet air feed had polymer electrolyte fuel cell type serpentine gas flow channel. Anode catalyst layer was 1.0 mg cm-2 of IrOx (TKK) with Nafion ionomer. The porous transport layer was platinum plated sintered titanium sheet. PEM was Nafion 117 (Du Point), cathode catalyst layer was 0.5 mg cm-2 of PtRu/C with Nafion ionomer supported on a porous flow field of a carbon paper that was loaded 0.02 mg cm-2 platinum for chemical reaction of toluene and hydrogen.5 mL min-1 of toluene or 10% toluene – methylcyclohexane and 1.0 L min-1 of wet air fed to cathode and anode, respectively. Operation temperature was 80oC. After the 100 % RH feed electrolysis, there is no product except methylcyclohexane in the liquid phase and water transportation from anode to cathode reduced one twentieth from the conventional electrolyzer fed 1 M H2SO4 operation at 60oC. In this condition, IR free cell voltage of the wet gas fed electrolyzer was significantly smaller than that of the conventional one because of high surface area anode. Internal resistance of the wet gas feed determined by AC impedance method was about two times higher than that of the conventional, and current efficiency maintained in the low current density region. The internal resistance increased in the high current density region where the membrane and ionomer dry up with electro osmosis water. In this region, current efficiency also decreases.In summary, wet gas feed water electrolysis for electrohydrogenation of toluene using a PEM electrolyzer is an interesting technology that combines water electrolyzer with water purification system and manages water feed to reduce water transportation to cathode to maintain current efficiency of with accurate control of relative humidity and gas feed amount.AcknowledgementThis study was based on results obtained from the Development of Fundamental Technology for Advancement of Water Electrolysis Hydrogen Production in Advancement of Hydrogen Technologies and Utilization Project (P14021) commissioned by the New Energy and Industrial Technology Development Organization (NEDO).References Nagasawa, K. Tanimoto, J. Koike, K. Ikegami, S. Mitsushima, J Power Sources, 439, 227070 (2019).Oi, K. Nagasawa, T. Takamura, Y. Misu, K. Matsuoka, S. Mitsushima, ECS Meeting s, MA2021-02, 1737 (2021).Mitsushima, Y. Sugita, J. Koike, Y. Kuroda, K. Matsuoka, Y. Sato, K. Nagasawa, ECS Meeting s, MA2020-02, 2494 (2020). Figure 1

Unsteady convective–diffusive transport in semicircular microchannels with irreversible wall reaction

The unsteady dispersion of a solute band by a steady pressure-driven flow in a semicircular microchannel is theoretically studied via the generalized dispersion model. Considering an irreversible first-order reaction at the curved wall while assuming a no-flux boundary condition at the flat wall, analytical solutions are obtained for the exchange, convection and dispersion coefficients as well as the dimensionless forms of solute concentration and mean solute concentration. The solutions are obtained assuming an initial solute band of arbitrary cross-sectional shape and axial distribution and the results are presented for both circular and semicircular shapes with the uniform distribution being a special case of the latter. Besides the general solutions, special solutions are also derived for uniform velocity and no-reaction cases. In the following, the influences of the initial concentration distribution and the Damköhler number, a measure of the reaction rate, on the transport coefficients and the concentration distribution are investigated in depth. It is demonstrated that the combination of the initial concentration distribution and the Damköhler number specifies the variations of the transport coefficients in the short term but the Damköhler number is the only parameter dominating the long-term values: the exchange and convection coefficients are increasing functions of the Damköhler number whereas the opposite is true for the dispersion coefficient. Moreover, we show that, provided the solute injection is appropriately positioned and shaped, liquid-phase transportation with little dispersion is possible in typical microchannels utilizing semicircular geometry.

Reduction of water chromaticity by materials with capillary properties

The presence of a significant amount of plant and animal organic residues in the environment leads to intensive pollution of natural waters and significant deterioration of water chromaticity. Ukrainian regulatory documents on the quality of drinking water establish a level of 20 degrees for water chromaticity. Hence, in most cases, natural water must be additionally treated before consumption. The coagulation, flocculation, filtration and flotation are today the most widespread methods for normalizing the water chromaticity level. All these processes are quite complex and expensive, require the use of additional reagents and lead to secondary water pollution. The use of materials with capillary properties is a promising method since it simultaneously ensures the liquid phase transport without excess pressure and water cleaning from various pollutants. This method, used to reduce water chromaticity, found that sufficient efficiency could be provided only for the initial water chromaticity level within 20 - 80° CCS and at pH level within 2.0 - 4.0. Under other conditions, all studied tissue samples as a material for capillary filter, such as cotton, linen, polyester and gabardine, did not provide the value of water chromaticity required for drinking water. Even worse results were obtained for water with initial chromaticity more than 80 degrees. Considering that the described method can provide the maximum efficiency only in a highly acidic medium, it is assumed that the surface charge of the capillary filter fibers and humic acid particles could be the critical factor in the reduction of water chromaticity. In a wide pH range, the surface of the humic particles is charged mainly negatively. The surface of cellulose fibers is also negatively charged in the pH range of 2.0 - 11.0. Therefore, the results of experiments can be explained from this point of view. There are no research data in these fields at all. One of the possible ways to improve the efficiency of water chromaticity reduction by the proposed method is to select fabrics with appropriate physicochemical surface properties. Also, capillary filtration process can be treated with special reagents for giving the fiber surface the required charge. Water treatment by series of several connected capillary filters can be a promising way. In general, given the simplicity of the filter design, low total cost of the water treatment process, and zero energy losses, the studied method is quite promising for industrial implementation and needs more detailed research.

Mathematical modeling of novel porous transport layer architectures for proton exchange membrane electrolysis cells

Thin foil based porous transport layers (PTLs) that contain highly structured pore arrays have shown promise as anode PTLs in proton exchange membrane electrolysis cells. These novel PTLs, fabricated with advanced manufacturing techniques, produce thin, tunable, multifunctional layers with reduced flow and interfacial resistances and high thermal and electric conductivities. To further optimize their design, it is important to understand their fundamental impact on the transport of protons, electrons, and liquid/vapor mixtures in the electrode. In this work, we develop a two-dimensional multiphysics model to simulate the coupled electrochemistry and multiphase transport in an electrolysis cell operated with the novel PTL architecture. The results show that larger pores improve access of water to the anode catalyst layer, which is beneficial for both the oxygen evolution reaction and membrane hydration. Larger pore sizes also improve oxygen gas transport from the catalyst layer, because generated oxygen gas is forced to travel in-plane through the anode catalyst layer until it reaches a pore opening that is connected to a channel. The discussed results confirm that the proposed thin foil based PTLs are fundamentally different from conventional PTLs, such as felts or layered meshes. The model developed in this work also provides generalizable insight into fundamental PEMEC phenomena, such as the competition between liquid and gas phase transport, membrane hydration and water management, and nonuniform electrochemical reactions, which are processes relevant to all PEMEC designs.

Role of Discharge-Product Morphology and Formation Rates in Li–O2 Battery Performance

Lithium–oxygen batteries have unprecedented theoretical capacity. Achieving the theoretical capacity in practice remains a challenge – even during low-power operation – because of higher-order phenomena that accompany the formation of discharge products, such as surface passivation and clogging of the cathode’s pores. In the last few years, Li–O2 battery research has moved towards systems that preferentially form large discharge-product particles, which can be achieved by using high-donicity electrolytes and including mediators as additives.1 In this study we examine the implications of discharge-product growth and morphology on performance using numerical simulations.A continuum model is developed which incorporates multicomponent mass transfer2 described by Onsager-Stefan-Maxwell laws. Including more details about liquid-phase transport is particularly important when modelling solution-mediated discharge processes, because the diffusion of soluble reaction intermediates can control the battery’s apparent discharge capacity. Detailed reaction models, which include precipitation and film-growth kinetics are also necessary, to elucidate the competition between discharge-product formation pathways3: thin-film formation can slow interfacial reaction kinetics, whereas pore clogging raises overpotentials by hindering the transport of reactive species.Large discharge products form through a solution-phase mechanism, which is favoured by electrolytes that sustain the presence of an LiO2 intermediate for a relatively long time. These intermediate forms the final Li2O2 discharge product either by electrochemically reacting with a lithium ion or by chemically disproportionating, thereby contributing to discharge-product-particle growth. When LiO2 reaction intermediates are long-lived, they can build up in the electrolyte, particularly near the electrode/electrolyte interface. Thus, the system is locally pushed from the dilute into the concentrated regime, and pairwise interactions between species can become significant to device performance.(1) Torayev, A.; Magusin, P. C. M. M.; Grey, C. P.; Merlet, C.; Franco, A. A. Text Mining Assisted Review of the Literature on Li-O2 Batteries . J. Phys. Mater. 2019, 2, 044004.(2) Liu, J.; Khaleghi Rahimian, S.; Monroe, C. W. Capacity-Limiting Mechanisms in Li/O2 batteries. Phys. Chem. Chem. Phys. 2016, 18, 22840–22851.(3) Yin, Y.; Torayev, A.; Gaya, C.; Mammeri, Y.; Franco, A. A. Linking the Performances of Li–O2 Batteries to Discharge Rate and Electrode and Electrolyte Properties through the Nucleation Mechanism of Li 2 O 2. J. Phys. Chem. C 2017, 121, 19577–19585.

Electroosmotic flow and heat transfer in a heterogeneous circular microchannel

Asymmetries in boundary condition are inevitable in practice in microfluidic channels, despite being rarely addressed from theoretical perspectives. Here, by arriving at closed form analytical solutions, we bring out a unique coupling between asymmetries in surface charge and heat transfer in electroosmotically driven microchannel flows. For illustration, we assume that the channel is laterally composed of two parts, each having specified values of the zeta potential and the wall heat flux. Considering low zeta potentials, we obtain analytical solutions in terms of infinite series for the dimensionless forms of the electric potential, the velocity, and the temperature distributions. We demonstrate that, by carefully adjusting the governing parameters, a variety of flow patterns may be achieved, a property that is crucial in applications such as liquid-phase transportation and mixing. Moreover, we show that the average velocity is a linear function of both the zeta potential ratio and the coverage factor. We further show that the average Nusselt number increases when part of the channel having the larger heat flux enlarges and the zeta potential of the part having the smaller surface charge increases. Hence, the maximum heat transfer rates are achieved when the boundary conditions are symmetrical.

Liquid spray transport of air–plasma-generated reactive species toward plant disease management

Liquid–phase transport of plasma-generated reactive species toward large-scale plasma treatment for agricultural applications is experimentally studied. The liquid-phase reactive species in this study are generated by the contact of water solution with air–plasma effluent gas containing mainly low-solubility reactive species under elevated pressure, followed by spraying the plasma effluent gas dissolved solution into a target pathogenic conidium suspension. Low-solubility ozone in the liquid phase at the target is found to dominate the observed germination suppression effect, which also correlates with the gas-phase ozone density. The measured ozone concentration at the target is found to be ten times lower than the ozone concentration at saturation, estimated from Henry’s law with the measured gas-phase ozone density. The liquid-phase ozone loss mechanism during the transport of the sprayed liquid is interpreted as volatilization and reactions with co-dissolved species. The deduced control parameters for precise ozone transport are the droplet diameter of the sprayed solution, sprayed jet flow, and co-dissolved reactant with the liquid-phase ozone such as nitrite.

Study of Dynamic Concentration Gradient on Mass Transfer Coefficient: New Approach to Mobile–Immobile Modeling

The theory of mobile–immobile partitioning to capture a medium’s heterogeneity for simulating the interaction of contaminant mass between these two regions is still limited to the lump value of mass transfer coefficient (MTC) that fails to capture the long tails of breakthrough curves (BTCs). For a time-dependent solute source, BTCs consists of two parts, for example, rising and falling limbs. During the rising part, the concentration in the mobile region is higher and mass transfer occurs from the mobile to immobile region. However, during falling limb concentration in the immobile region have higher values, resulting in the reverse diffusive mass transfer process. This study focuses on overcoming the reported limitations of the mobile–immobile model (MIM) in the prediction of long tails of BTC during the falling limb. To achieve this objective, we propose an approach that is based on the dynamics of time resident concentration and its gradient between hydraulically coupled mobile and immobile regions. In this modified MIM, we estimated two distinct diffusive MTCs for rising and falling limbs (RFMT) of BTCs using a nonlinear least square optimization algorithm. Two experimental data sets available in the literature were simulated using a numerical solution of the proposed model and asymptotic time-dependent dispersion function. The estimated parameters supported the hypothesis that for pulse type input, liquid phase transport during the rising limb of BTCs is governed by advection and dispersion, whereas during the falling limb it is majorly diffusive dominated that can be represented by the new MTCs. Simulated results of RFMT are then compared with continuous-time random walk (CTRW) and constant mass transfer (CMT) approaches to compare the quality of the simulation. A better overall simulation of experimental BTCs was obtained using RFMT in comparison with other models. Sensitivity analysis is also carried out to evaluate the capabilities of RFMT over the rising and falling portions of BTCs. This theory finds its application in quantifying persistent chemical residuals in the immobile region that acts as a source when purging and subsequently helps when designing appropriate cleansing operations.

Effect of TiO2 on fluoride evaporation from CaF2–CaO–Al2O3–MgO–Li2O–(TiO2) slag

ABSTRACT The present work was carried out to study the evaporation of fluoride from CaF2–CaO–Al2O3–MgO–Li2O–(TiO2) slag with different TiO2 contents. The evaporation ratio is determined by monitoring the weight change of the slag by isothermal thermogravimetric analysis in the temperature range of 1470–1530°C. The results show that the evaporation ratio of fluoride is promoted by increasing temperature and adding TiO2 content from 0 to 13.28 wt-%. It has a slight effect to enhance the fluoride evaporation ratio when the TiO2 content exceeds 8.67 wt-%. CaF2 and AlF3 are major constituents of the evaporation substances. The evaporation of fluoride is affected by the vapour pressure of AlF3 and the viscosity of slag. The evaporation process for TiO2-containing slags is controlled by a chemical reaction in the beginning, followed by a mixed reaction-mass transfer regime, and the limiting factor is the liquid-phase mass transport in the end.

A Review of Pipeline Transportation Technology of Carbon Dioxide

CO2from industrial production is captured and stored to be buried underground or used for driving oil or gas(CCS). The CCS technology can be used not only to mitigate environmental pollution and reduce the anthropogenic greenhouse effect, but to improve economic efficiency. CO2 transportation is imperative, and pipeline transportation is the most economical and convenient way for CO2 transportation because of its features such as large-throughput, long-distance and reliable-operation. According to the different phases, CO2 pipeline transportation can be divided into gas phase, liquid phase, dense phase and supercritical transportation. In this paper, the characteristics and application ranges of three kinds of pipeline transportation process were analyzed, finally in a design influence factors of pipeline transportation were analyzed, and faced currently of problems were shown.

A Mass and Charge Conserving Tanks-in-series Model for Lithium-Ion Batteries

The incorporation of physics-based lithium-ion battery models in real-time optimization, control and estimation has the potential to substantially facilitate their efficient and safe operation.1,2 In addition to improved prediction of battery states, the access to predictions of variables internal to battery electrochemistry allows the formulation of more complete optimization and control problems than would be possible by simple circuit models.3 Various approaches have been employed to enable this integration by reducing the computational demands of electrochemical models, particularly for the macro-homogeneous ‘P2D’ models of Newman and co-workers.4 These may be broadly divided into two categories: simplifications of the full model subject to limiting assumptions,5–7 or reformulation techniques which exploit the underlying structure of model equations to achieve fast simulation.1,8,9 The single particle model (SPM) visualizes the electrodes in a lithium-ion battery as two spherical particles and considers the electrode reactions and lithium transport through the active particle. Importantly however, it neglects potential and concentration variations in the electrolyte phase, which limits its predictive ability to low-current scenarios. Reformulated P2D models offer the desired computational performance without sacrificing physical detail, but their utility is dependent on the precise estimation of a large number of parameters from experimental data.10 This talk focuses on the development of a lumped physics-based model for lithium-ion batteries. The governing equations of the P2D model are integrated over the volume of each region in a cathode-separator-anode representation. This results in a set of volume-averaged quantities and relations, with the temporal evolution of each averaged variable expressed as an overall balance containing internal source terms and interfacial fluxes, which need to be approximated. The averaged porous domains may thus be regarded as three ‘tanks-in-series’. The model equations are simulated, and the electrochemical variable predictions compared against both the full P2D model and SPM over a range of parameter combinations and operating conditions. Various approximations for the interfacial fluxes are also evaluated in terms of their impact on cell-level predictions. The model is also extended to incorporate thermal effects via volume-averaged energy balances. Model predictions for different galvanostatic discharge rates suggest that the lumped model is of intermediate sophistication between the SPM and the P2D models. This is most likely because it incorporates liquid phase transport in an average sense, in contrast to SPM, which ignores them entirely. The lumped model is conservative, and possesses the computational simplicity of SPM, while also incorporating elements from the P2D model, but with a smaller number of parameters, making it easier to parameterize and potentially facilitating use in real-time prediction and control. In addition, tank models have been extensively researched in control theory, enabling the extension of these concepts to battery systems through lumped models. The ‘tanks-in-series’ averaging procedure described herein may be generalized to any electrochemical battery model. Acknowledgements The authors are also thankful for financial support from the Battery500 Consortium and the Advanced Research Projects Agency (ARPA-E). The authors acknowledge financial support from the Department of Chemical Engineering and the Clean Energy Institute at the University of Washington. References A. M. Bizeray, S. Zhao, S. R. Duncan, and D. A. Howey, J. Power Sources, 296, 400 (2015).V. Ramadesigan, P. W. C. Northrop, S. De, S. Santhanagopalan, R. D. Braatz, and V. R. Subramanian, J. Electrochem. Soc., 159, R31 (2012).M. Pathak, D. Sonawane, S. Santhanagopalan, R. D. Braatz, and V. R. Subramanian, ECS Trans., 75, 51 (2017).M. Doyle, T. J. Fuller, and J. Newman, J. Electrochem. Soc., 140, 1526 (1993).S. Santhanagopalan and R. E. White, J. Power Sources, 161, 1346 (2006).B. S. Haran, B. N. Popov, and R. E. White, J. Power Sources, 75, 56 (1998).M. Guo, G. Sikha, and R. E. White, J. Electrochem. Soc., 158, A122 (2011).P. W. C. Northrop, V. Ramadesigan, S. De, and V. R. Subramanian, J. Electrochem. Soc., 158, A1461 (2011).P. W. C. Northrop, M. Pathak, D. Rife, S. De, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 162, A940 (2015).V. Ramadesigan, K. Chen, N. A. Burns, V. Boovaragavan, R. D. Braatz, and V. R. Subramanian, J. Electrochem. Soc., 158, A1048 (2011).