Decreasing Mole Fraction Research Articles

On the Maximum Obtainable Purity and Resultant Maximum Useful Membrane Selectivity of a Membrane Separator.

Design considerations concerning the maximum purity of a membrane separator, and the resultant maximum effective selectivity of the membranes were explored by modeling a binary gas membrane separator (pressure-driven permeance) using a dimensionless form. Although the maximum purity has an analytical solution at the limit of zero recovery or stage cut, this solution over-predicts the obtained purity as the recovery is increased. Furthermore, at combinations of high recovery, low feed mole fraction, and low pressure ratio, the maximum purity becomes independent of selectivity above some critical selectivity. As a consequence of this purity limitation, a maximum selectivity is defined at which further increases in selectivity will result in less than a 1% change in the final purity. An equation is obtained that specifies the region in which a limiting purity is less than unity (indicating the existence of a limiting selectivity); operating at less than the limiting pressure ratio results in a purity limitation less than unity. This regime becomes larger and more significant as the inlet mole fraction decreases (e.g., inlet feed mole fraction of 10% and pressure ratio of 100 results in a maximum useful membrane selectivity of only 130 at 95% recovery). These results suggest that membrane research should focus on increasing permeance rather than selectivity for low-concentration separations. The results found herein can be used to set benchmarks for membrane development in various gas separation applications.

Aqueous solutions of non-ionic surfactant mixtures as mediums for green extraction of polyphenols from red grape pomace

Grapevine production is predominantly oriented towards winemaking, consequently generating large amount of polyphenol-rich waste. Micellar solutions of surfactants are recognized for their ability to efficiently solubilize compounds from different plant material. This study examined potential of water solutions of mixtures of non-ionic surfactants Brij S20 (BS20) and poloxamer 407 (P407) for the extraction of polyphenols from red grape pomace. Critical micelle concentrations of extraction mediums (mixtures of BS20/P407 1:1, 1:9 and 9:1) were determined. Total phenolic content, individual phenolic profile and antioxidant capacity of extracts were examined. Measurement of hydrodynamic radii of micelles before and after extraction was performed. Water, water:ethanol (1:1) and pure BS20 and P407 extracts were used for comparison. Values of experimental critical micelle concentrations decreased with decreasing mole fraction of P407 and synergistic interactions between components of mixed micelles were observed. Total phenolic contents of BS20/P407 (9:1) and (1:1) extracts were 54.49 ± 0.12 and 54.73 ± 0.26 mg GAE/g DW, respectively, and these values are up to 19% higher than those obtained with pure surfactants. The most pronounced increase in solubilization efficiency in mixed micelles (BS20/P407 (1:1) and (9:1)) was observed for less polar compounds (e.g., quercetin, kaempferol and rutin) compared to a single-surfactant-micelles. All investigated systems showed an increase in micelle size after extraction. The present study has demonstrated green method for extraction of polyphenols from grape pomace with assistance of water solutions of non-ionic surfactant mixtures, which could be useful for further practical applications.

Phase transitions study of the liquid crystal DIO with a ferroelectric nematic, a nematic, and an intermediate phase and of mixtures with the ferroelectric nematic compound RM734 by adiabatic scanning calorimetry.

High-resolution calorimetry has played a significant role in providing detailed information on phase transitions in liquid crystals. In particular, adiabatic scanning calorimetry (ASC), capable of providing simultaneous information on the temperature dependence of the specific enthalpy h(T) and on the specific heat capacity c_{p}(T), has proven to be an important tool to determine the order of transitions and render high-resolution information on pretransitional thermal behavior. Here we report on ASC results on the compound 2,3',4',5'-tetrafluoro[1,1'-biphenyl]-4-yl 2,6-difluoro-4-(5-propyl-1,3-dioxan-2-yl) benzoate (DIO) and on mixtures with 4-[(4-nitrophenoxy)carbonyl]phenyl 2,4-dimethoxybenzoate (RM734). Both compounds exhibit a low-temperature ferroelectric nematic phase (N_{F}) and a high-temperature paraelectric nematic phase (N). However, in DIO these two phases are separated by an intermediate phase (N_{x}). From the detailed data of h(T) and c_{p}(T), we found that the intermediate phase was present in all the mixtures over the complete composition range, albeit with strongly decreasing temperature width for that phase with decreasing mole fraction of DIO (x_{DIO}). The x_{DIO} dependence on the transition temperatures for both transitions could be well described by a quadratic function. Both these transitions were weakly first order. The true latent heat of the N_{x}-N transition of DIO was as low as L=0.0075±0.0005J/g and L=0.23±0.03J/g for the N_{F}-N_{x} transition, which is about twice the previously reported value of 0.115 J/g for the N_{F}-N transition in RM734. In the mixtures both transition latent heats decrease gradually with decreasing x_{DIO}. At all the N_{x}-N transitions pretransition fluctuation effects are absent and these transitions are purely but very weakly first order. As in RM734 the transition from the N_{F} to the higher-temperature phase exhibits substantial pretransitional behavior, in particular, in the high-temperature phase. Power-law analysis of c_{p}(T) resulted in an effective critical exponent α=0.88±0.1 for DIO and this value decreased in the mixtures with decreasing x_{DIO} toward α=0.50±0.05 reported for RM734. Ideal mixture analysis of the phase diagram was consistent with ideal mixture behavior provided the total transition enthalpy change was used in the analysis.

Self-assembly of Quillaja saponin mixtures with different conventional synthetic surfactants

Saponins are surface active glycosides which can be extracted from a range of different plant species. This class of biosurfactants is of much current interest because of their biocompatibility and biosustainability, and a range of other interesting properties. The Quillaja saponin, the focus of this paper, is extensively used in foods, beverages and cosmetics due to their accessibility and agency approval. Aspects of their wider application rests with their use in combination with different synthetic surfactants, to optimise and tailor performance and functionality. Characterising and understanding the self-assembly of such mixtures is an essential requirement for that wider exploitation. The surface activity of a range of different saponins has been extensively reported, but the self-assembly properties of the Quillaja saponin, and its mixture with different synthetic surfactants has not been reported in any detail. Of particular interest is how the bidesmodic structure of the Quillaja saponin and the mixing with the different cosurfactants affects the evolution in the micelle structure, and this is the focus of this study. Small angle neutron scattering, SANS, has been used to characterise the micelle formation of the Quillaja saponin and of its mixtures with the anionic surfactant sodium dodecyl sulfate, SDS, and the nonionic surfactants, dodecaethylene glycol monododecyl ether, C12E12, and pentaethylene glycol monododecyl ether, C12E5. The Quillaja saponins form relatively small globular micelles with a relatively small aggregation number. In mixtures with SDS and the nonionic surfactants the micelles retain their globular structure. In the mixtures the micelle aggregation number evolves towards the value for the pure synthetic surfactant component, as the packing constraints change with the decreasing mole fraction of saponin in the micelle. The evolution in the micelle structure and size reflects the change in the structure and geometry of the associated surfactant components, and is largely dominated by the Quillaja structure. The results provide an interesting insight into the factors controlling the self-assembly in saponin – surfactant mixtures, and how the saponin structure affects the self-assembly.

Investigation of the impact of the reactants temperature and equivalence ratio on the outlet mixture temperature, velocity and mole fraction for the combustion of the carbon monoxide and nitrous

In the present study, a numerical code is used for three-dimensional simulation of non-premixed form of the combustion of nitrous-carbon monoxide mixture. This code includes standard K-ε as turbulent model and Probability Density Function (PDF) as thermo-chemistry approach. Ten species i.e. nitrous, carbon monoxide, carbon dioxide, nitrogen, nitrogen monoxide, atomic oxygen, oxygen, ozone, cyanate and atomic carbon are assumed contributing in this reaction. For the validation of model, experimental measurement of previous studies are applied. The influence of equivalence ratio and inlet gases temperature, on outlet mixture velocity, temperature and outlet species mole fraction are obtained in the form of charts for wide ranges, which was not clearly obtained in previous works. These charts are useful for designer of these systems. Results indicate, when Ø ≥ 0.15 N2O is decomposed completely and the maximum mole fractions for O2(approximately 0.27), N2 (approximately 0.77) and O3 (depending on the temperature) are obtained. Furthermore, it was found the mole fraction of the outlet carbon dioxide and dimensionless temperature of the outlet mixture are maximum at equivalence ratio equal to unity and if the temperature of the inlet gases is kept constant and the equivalence ratio reduces, the outlet carbon monoxide mole fraction decreases.

Thermodynamic analyses of thermal evaporation of BaSi2

Thermal evaporation is a useful method for the deposition of high-quality photovoltaic BaSi2 films. The elemental processes of BaSi2 film formation are, however, complicated due to vapor composition change during BaSi2 evaporation. In this study, we thermodynamically calculate the vapor composition for quantitative explanation of the evaporation process. The Ba and Si vapor fluxes are calculated from relative partial molar enthalpies of Ba and Si in Ba–Si melt. Calculations show a tendency of decreasing Ba vapor flux and increasing Si flux with decreasing mole fraction of Ba in Ba–Si melt, by which the vapor composition change from being Ba-rich to being Si-rich during thermal evaporation of BaSi2 is successfully explained. The calculation results are discussed by comparing with the depth profiles of evaporated films deposited at room temperature and deposition rate. The present results would be useful as a theoretical basis of thermal evaporation of BaSi2.

Interfacial and Aggregation Behavior of Dicarboxylic Amino Acid-Based Surfactants in Combination with a Cationic Surfactant.

The interfacial and micellization behavior of three dicarboxylic amino acid-based anionic surfactants, abbreviated as AAS (N-dodecyl derivative of -aminomalonate, -aspartate, and -glutamate) in combination with hexadecyltrimethylammonium bromide (HTAB) were investigated by surface tension, conductance, UV-vis absorption/emission spectroscopy, dynamic light scattering (DLS), and viscosity studies. Critical micelle concentration (CMC) values of the surfactant mixtures are significantly lower than the predicted values, indicating associative interaction between the components. Surface excess, limiting molecular area, surface pressure at the CMC, and Gibbs free energy indicate spontaneity of the micellization processes compared to the pure components. CMC values were also determined from the sigmoidal variation in the plot of micellar polarity and pyrene UV-vis absorption/emission intensities with surfactant concentration. The aggregation number, determined by static fluorescence quenching method, increases with decreasing mole fraction of the AAS (αAAS), where the micelles are mainly dominated by the HTAB molecules. The size of the micelle increases with decreasing αAAS, leading to the formation of larger and complex aggregates, as also supported by the viscosity studies. Micelles comprising 20-40 mol % AAS are highly viscous, in consonance with their sizes. Some of the mixed surfactant systems show unusual viscosity (shear thickening and increased viscosity with increasing temperature). Such mixed surfactant systems are considered to have potential in gel-based drug delivery and nanoparticle synthesis.

Distance Angle Descriptors of the Interionic and Ion-Solvent Interactions in Imidazolium-Based Ionic Liquid Mixtures with Aprotic Solvents: A Molecular Dynamics Simulation Study.

The aim of this paper is to quantify the changes of the interionic and ion-solvent interactions in mixtures of imidazolium-based ionic liquids, having tetrafluoroborate (BmimBF4), hexafluorophosphate (BmimPF6), trifluoromethylsulfonate (BmimTFO), or bis(trifluoromethanesulfonyl)imide (BmimTFSI), anions, and polar aprotic molecular solvents, such as acetonitrile (AN), γ-butyrolactone (GBL), and propylene carbonate (PC). For this purpose, we calculate, using the nearest-neighbor approach, the average distance between the imidazolium ring H atom in positions 2, 4, and 5 (H2,4,5) and the nearest high-electronegativity atom of the solvent or anion (X) as distance descriptors, and the mean angle formed by the C2,4,5-H2,4,5 bond and the H2,4,5···X axis around the H2,4,5 atom as angular descriptors of the cation-anion and cation-solvent interactions around the ring C-H groups. The behavior of these descriptors as a function of the ionic liquid mole fraction is analyzed in detail. The obtained results show that the extent of the change of these descriptors with respect to their values in the neat ionic liquid depends both on the nature of the anion and on the mixture composition. Thus, in the case of the mixtures of the molecular solvents with BmimBF4 and BmimTFO, a small change of the distance and a drastic increase of the angular descriptor corresponding to the cation-anion interactions are observed with decreasing mole fraction of the ionic liquid, indicating that the anion moves from the above/below position (with respect to the imidazolium ring plane) to a position that is nearly linearly aligned with the C2-H2 bond and hinders the possible interaction between the C2-H2 group and the solvent molecules. On the other hand, in the case of mixtures of BmimTFSI and BmimPF6 with the molecular solvents, both the observed increase of the distance descriptor and the slight change of the angular descriptor with decreasing ionic liquid mole fraction are compatible with the direct interactions of the solvent with the C2-H2 group. The behavior of these descriptors is correlated with the experimentally observed 1H chemical shift of the C2-H2 group and the red shift of the C2-H2 vibrational mode, particularly at low ionic liquid mole fractions. The present results are thus of great help in interpreting these experimental observations.

동축형 분사기의 연소 특성에 영향을 주는 인자에 관한 연구

Factors affecting the combustion characteristics of gas-centered swirl coaxial (GCSC) injectors are investigated numerically and experimentally. The factors are fuel volume flow rate (Qf), momentum flux ratio (MFR) and oxidizer/fuel (O/F) ratio. Firstly, the flame pattern becomes asymmetric as the fuel volume flow rate increases with a fixed momentum flux ratio. Then, the suitable fuel volume flow rate is selected according to the results. Next, the momentum flux ratio is increased by increasing the oxidizer volume flow rate (QSUBo/SUB) with a fixed fuel volume flow rate. Results show that the spreading angle decreases as momentum flux ratio increases, which agrees with our previous results. Finally, in order to check effects of oxidizer/fuel ratio, the QSUBf/SUB, QSUBo/SUB, and MFR are kept the same but the O₂ mole fraction of oxidizer is changed. From numerical and experimental results, it is found that flame pattern depends on oxidizer/fuel ratio and spreading angle increases as the O₂ mole fraction decreases.

Measurement and correlation for solubilities of isophthalic acid and m-toluic acid in binary acetic acid + water and acetic acid + m-xylene solvent mixtures

In this study, the solubilities of isophthalic acid (IPA) and m-toluic acid (m-TA) in binary acetic acid (HAc) + (water or m-xylene) solvent mixtures were measured by using a synthetic method at atmospheric pressure. The mole fraction of HAc in the corresponding solvent mixtures ranges from 0.0000 to 1.000. The measured data show that within the temperature range studied, the solubilities of IPA and m-TA increase with increasing temperature at constant solvent composition. At a given temperature, the solubilities of IPA and m-TA decrease with the decreasing mole fraction of HAc in HAc + water solvent mixtures; whereas the “maximum-solubility effect” was observed in HAc + m-xylene solvent mixtures, and that with the mole fraction of HAc at 0.8761 has the best dissolving capacity for IPA at constant temperature. The experimental solubilities were well correlated by both the nonrandom two-liquid (NRTL) and Apelblat equations, and the calculated solubilities agree satisfactorily with the measured results. Furthermore, the thermodynamic functions including dissolution enthalpy, entropy and Gibbs energy were obtained from the solubility data by using the van't Hoff equation.

Measurement and correlation of solubility of boscalid with thermodynamic analysis in pure and binary solvents from 288.15 K to 313.15 K

The solubility of boscalid in five pure solvents, including methanol, ethanol, isopropanol, ethyl acetate and n-propyl acetate, and two binary solvent mixtures, including (ethanol+ethyl acetate) and (isopropanol+ethyl acetate), was determined by a gravimetric method with temperatures ranging from (288.15 to 313.15) K. It turns out that the solubility of boscalid increases with the increasing of temperature in all selected solvents. Moreover, it is interesting that the solubility of boscalid in the two binary solvent mixtures performed a maximum effect with the decreasing mole fraction of ethyl acetate at a given temperature. The solubility of boscalid in pure solvents was correlated by the modified Apelblat model and λh model while that in binary solvent mixtures was correlated by the modified Apelblat model, CNIBS/R-K model and Jouyban-Acree model. It is found that all the models could give satisfactory correlation results with less than 3% of all the ARD values. Furthermore, the thermodynamic properties of the mixing processes in all solvents selected were calculated and discussed based on the NRTL model.

Solubilities of Phthalic Acid and o-Toluic Acid in Binary Acetic Acid + Water and Acetic Acid + o-Xylene Solvent Mixtures

The solubilities of phthalic acid and o-toluic acid in binary acetic acid (HAc) + water and HAc + o-xylene solvent mixtures were measured by a dissolution temperature method at atmospheric pressure. The mole fractions of HAc in the corresponding solvent mixtures range from 0.00 to 1.00. The measured data show that, within the temperature range studied, the solubilities of phthalic acid and o-toluic acid increase with the increasing temperature at constant solvent composition and initially decrease with the decreasing mole fraction of HAc in HAc + o-xylene and HAc + water solvent mixtures at constant temperature, respectively. It also shows that, within the solvent composition range studied, the HAc + water solvent mixtures with the mole fraction of HAc at 0.5467 has the highest dissolving capacity for phthalic acid at constant temperature, and the highest solubility of o-toluic acid is obtained in HAc + o-xylene solvent mixtures with the mole fraction of HAc of 0.5408 at constant temperature. The experime...

Surface Structure and Dynamics of Ions at the Liquid–Vapor Interface of Binary Ionic Liquid Mixtures: Molecular Dynamics Studies

The surface structure and dynamics of ions at the liquid–vapor interface of binary mixtures of ionic liquids 1-n-octyl-3-methylimidazolium trifluoromethanesulfonate ([omim][TfO]) and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][TfO]) of varying composition have been studied using atomistic molecular dynamics simulations. Global definition of the interface and the identification of the truly interfacial molecule method (ITIM) have been used to analyze the structure and dynamics of the ions at the interface. We have seen enhancement in the density of the longer alkyl chain cation ([omim]) at the liquid–vapor interface compared to the bulk. The surface is mainly enriched with the [omim] cation, and it becomes smoother with a decrease in mole fraction of [omim] cations in the mixtures. The [omim] cation shows greater survival probability at the liquid–vapor interface than other ions, and this probability increases with a decrease in mole fraction of [omim] cations. The reorientational correla...

Role of toluene to acid gas (H2S and CO2) combustion in H2/O2–N2 flame under Claus condition

Abstract Experimental results are presented from the combustion of toluene with CO 2 and H 2 S gas in H 2 /O 2 –N 2 flames at an equivalence ratio of Φ = 3 (Claus condition). The results from the combustion of 100% H 2 S, H 2 S/C 7 H 8 and H 2 S/C 7 H 8 /CO 2 acid gases are also reported. The results showed a decrease in mole fraction of H 2 S and simultaneous evolution of SO 2 in H 2 S/H 2 /O 2 –N 2 flame. In contrast, combustion of H 2 S/C 7 H 8 acid gas showed faster initial SO 2 formation to a maximum mole fraction, but the formed SO 2 decomposed further downstream in the reactor. This is in further contrast to that of H 2 S/C 7 H 8 /CO 2 acid gas combustion, where CO 2 acted as an oxidizer (released atomic oxygen) that furthered SO 2 formation. The results also revealed the formation of CH 4 , C 2 H 2 and CS 2 with the addition of toluene. The presence of CO 2 enhanced the formation of mercaptans (COS and CS 2 ) and decomposition of formed hydrocarbons in the reactor. These results help to identify conditions under which hydrocarbons and mercaptans (COS and CS 2 ) are formed, and how they can be mitigated during sulfur and energy recovery from acid gases.

Solubilities of 5,10,15,20-tetrakis(4-chlorophenyl) porphyrin and 5,10,15,20-tetrakis(4-chlorophenyl) porphyrin manganese(III) chloride in binary ethanol + water solvent mixtures

The solubilities of 5,10,15,20-tetrakis(4-chlorophenyl) porphyrin (abbreviated in p-ClTPP) in ethanol+water solvent mixtures at (293.2–333.2)K and 5,10,15,20-tetrakis(4-chlorophenyl) porphyrin manganese(III) chloride (abbreviated in p-ClTPPMnCl) in ethanol+water solvent mixtures at (303.2–333.2) K were measured. The concentration of ethanol in term of mole fraction on the solubility was studied. It was found that the solubility of p-ClTPP in ethanol+water solvent mixtures increases with the increasing of temperature at constant solvent composition, and decreases with the decreasing mole fraction of ethanol at constant temperature. However, for p-ClTPPMnCl, the solubility increases with the increasing of temperature at the mole fraction of ethanol from (0.6102–0.8597), and decreases with the increasing of temperature at the mole fraction of ethanol from (0.9038–1.0000). The experimental data were correlated with the modified Apelblat equation, and the solubilities correlated by the model were in good agreement with experimental data. Thermodynamic parameters including dissolution enthalpy, dissolution entropy and dissolution Gibbs free energy were calculated with van’t Hoff equation.

Improved method for determining binary adsorption isotherms by using concentration pulse chromatography: adsorption of CO2 and N2 by silicalite at different pressures

Adsorption separation of carbon dioxide from nitrogen at different system total pressures with silicalite as the adsorbent was studied by using concentration pulse chromatography. Improving the methodology for determining binary adsorption isotherms by concentration pulse method (CPM) was also the goal of this study. Binary adsorption isotherms, x–y phase diagrams and separation factor plots have been determined at 26 °C to look at the influence of pressure on the separation using concentration pulse chromatography. Available methods for determining binary adsorption isotherms using CPM have been reviewed and shown to be incapable of interpreting this particular binary system. An improved novel model has been proposed to interpret the data in this study. It has been referred to as the Kennedy-Tezel concentration pulse method (KT-CPM) and has been shown to be superior to other methods used in the literature. Results using this data were found to be consistent with the previous results in the literature. The binary isotherms for the CO2–N2 system show a decrease in CO2 selectivity as total system pressure increases. The optimal separation factor for silicalite was found to increase with decreasing system pressure and decreasing mole fraction of CO2 in the feed mixture.

3D CFD modeling of acetone hydrogenation in fixed bed reactor with spherical particles

Acetone hydrogenation in a fixed bed reactor packed with spherical catalyst particles was simulated to study the effects of inlet gas velocity and particle diameter on hydrogenation reaction. Computational results show that the catalyst particles in the reactor are almost isothermal, and the high isopropanol concentration appears at the lee of the particles. With the increase of inlet velocity, the outlet isopropanol mole fraction decreases, and the total pressure drop increases drastically. Small diameter catalyst particles are favorable for acetone hydrogenation, but result in large pressure drop.

Stability Assessment of Gas Mixtures Containing Monoterpenes in Varying Cylinder Materials and Treatments

Studies of climate change increasingly recognize the diverse influences exerted by monoterpenes in the atmosphere, including roles in particulates, ozone formation, and oxidizing potential. Measurements of key monoterpenes suggest atmospheric mole fractions ranging from low pmol/mol (parts-per-trillion; ppt) to nmol/mol (parts-per-billion; ppb), depending on location and compound. To accurately establish the mole fraction trends, assess the role of monoterpenes in atmospheric chemistry, and relate measurement records from many laboratories and researchers, it is essential to have good calibration standards. The feasibility of preparing well-characterized, stable gas cylinder standards for monoterpenes at the nmol/mol level was previously tested using treated (Aculife IV) aluminum gas cylinders at NIST. Results for 4 of the 11 monoterpenes, monitored versus an internal standard of benzene, indicated stability in these treated aluminum gas cylinders for over 6 months and projected long-term (years) stability. However, the mole fraction of the key monoterpene β-pinene decreased, while the mole fractions of α-pinene, d-limonene (R-(+)-limonene), p-cymene, and camphene (a terpene not present in the initial gas mixture) increased, indicating a chemical transformation of β-pinene to these species. A similar pattern of decreasing mole fraction was observed in α-pinene where growth of d-limonene, p-cymene, and camphene has been observed in treated gas cylinders prepared with a mixture of just α-pinene and benzene as the internal standard. The current research discusses the testing of other cylinders and treatments for the potential of long-term stability of monoterpenes in a gas mixture. In this current study, a similar pattern of decreasing mole fraction, although somewhat improved short-term stability, was observed for β-pinene and α-pinene, with growth of d-limonene, p-cymene, and camphene, in nickel-plated carbon steel cylinders. β-Pinene and α-pinene showed excellent stability at over 6 months in aluminum cylinders treated with a different process (Experis) than used in the original study.

Dissolution Process of an Aluminum Anode in Acidic AlCl<sub>3</sub>-BMIC Ionic Liquid

The dissolution process of an aluminum electrode in Lewis acidic ionic liquid aluminum chloride (AlCl3 )-1-butyl-3-methylimidazolium chloride (BMIC) was studied using linear sweep voltammetry. Passivation was observed upon anodic polarization of the aluminum electrode that was caused by formation of a solid AlCl3 layer on the surface of the aluminum electrode. The electrochemical dissolution process of aluminum can be divided into electrochemically-controlled, transition, and passivation regimes. In the electrochemically-controlled regime, the dissolution rate of aluminum increased with increasing potential. In the transition regime, the dissolution rate of aluminum decreased as the potential increased because of the formation of solid AlCl3 caused by changes in the concentration of AlCl4-and Al2Cl7- . After a passivation layer formed, the dissolution rate of aluminum depended on the diffusion of AlCl4-was independent of potential; that is, the electrochemical dissolution process entered the passivation regime. The anodic limiting current density increased with agitation, increasing temperature, and decreasing mole fraction of AlCl3 in the ionic liquid.

Air flow modeling and performance prediction of the integrated-planar solid oxide fuel cell IP-SOFC

Modeling the air flow through an array of the integrated-planar solid oxide fuel cell (IP-SOFC) is very important for the optimization of the cell performance. The finites differences and the lattices Boltzmann methods are used to predict the evolution of the IP-SOFC fuel cell parameters. The effects of the inlet air velocity, the temperature and the pressure on the cell performance are investigated. The results indicate that the oxygen mole fraction decreases and the polarization concentration increases in the x-direction. The voltage losses became more and more important for the module of the next bundle, caused by the oxygen depleting. An increase in the inlet air velocity can reduce the oxygen mole fraction decrease and decrease polarization losses, however the concentration polarizations decrease imperceptibly with increasing temperature.