Capacity Titration Technique for Determining the Solid Diffusion Coefficient of Intercalary Species within Insertion-host Materials

In this paper, the capacity titration technique （CT technique） was developed on basis of the RPG （ratio of potentio-charge capacity to galvano-charge capacity） method to continuously determine the solid diffusion coefficient D of the intercalary species within insertion-host materials with a small voltage region. The linear equations of D vs. q （value of ratio of the potentio-charge capacity to the galvano-charge capacity） were given in different range of q. By the CT technique,the Li^＋ solid diffusion coefficients D within LiMn2O4 at different voltages were determined. The results showed that the values of D varied from 3.447×10^-9 cm^2/s to 7.60×10^-11 cm^2/s in the voltage range of charge from 3.3V to 4.3V as a function of voltage with “W” shape.

Prediction of Core-Annulus Solids Mass Transfer Coefficient in Gas-Solid Fluidized Bed Risers

Based on analysis of energy dissipation in the core region of gas-solid fluidized bed risers, a simplified model for determination of core-annulus solids mass transfer coefficient was developed according to turbulent diffusion mechanism of particles. The simulation results are consistent with published experimental data. Core-annulus solids mass transfer coefficient decreases with increasing particle size, particle density and solids circulation rate,but generally increases with increasing superficial gas velocity and riser diameter. In the upper dilute region of gas-solid fluidized bed risers, core-annulus solids mass transfer coefficient was found to change little with the axial coordinate in the bed.

Fluidization characteristics of different sizes of quartz particles in the fluidized bed

Fluidization characteristics of quartz particles with different sizes are experimentally investigated in a fluidized bed with an inner diameter of 300 mm and height of 8250 mm.Results show that the average solid holdup increases with the increase in superficial gas velocity and the decrease in initial solid holdup in the dense zone of the fluidized bed.The average cross-sectional solid holdup decreases with increasing bed height and superficial gas velocity.The bed expansion coefficient increases with the increase in superficial gas velocity and the decrease in solid holdup.Correlations of average solid holdup,average cross-sectional solid holdup and bed expansion coefficient are also established and discussed.These correlations can provide guidelines for better understanding of the fluidization characteristics.

PLEMELJ FORMULA OF CAUCHY TYPE INTEGRAL ON STEIN MANIFOLDS

Let D be a bounded domain with piecewise C^（1） smooth orientable boundary on Stein manifolds, and let Φ（z） be a Cauchy type integral with Bochner-Martinelli kernel Ω（φ^V, S^-, S） and Holder continuous density function φ（ζ）, the authors define a solid angular coefficient α（t） at the point t∈δD, prove that there exist the interior and outer limit values Φ^±（t） under the meaning of the Cauchy principal value, and obtain the more general Plemelj formula and jump formula.

Steady rotation of a composite sphere in a concentric spherical cavity

The problem of steady rotation of a composite sphere located at the centre of a spherical container has been investigated. A composite particle referred to in this paper is a spherical solid core covered with a permeable spherical shell. The Brinkman＇s model for the flow inside the compos- ite sphere and the Stokes equation for the flow in the spheri- cal container were used to study the motion. The torque ex- perienced by the porous spherical particle in the presence of cavity is obtained. The wall correction factor is calculated. In the limiting cases, the analytical solution describing the torque for a porous sphere and for a solid sphere in an un- bounded medium are obtained from the present analysis.

Direct Solutions of Some Singular Integral Equations on the Building Domain of Complex Biballs

By means of the method of solid angle coefficients and the permutation formula on the building domain of complex biballs,direct solutions of some singular integral equations with variable coefficients are discussed and the explicit formulas for these solutions are obtained.

THE POINCAR-BERTRAND FORMULA ON THE BUILDING DOMAIN OF COMPLEX BIBALLS

The Poincare-Bertrand formula takes an important position in the study of complex singular integral. The Poincare-Bertrand formula on the complex sphere in the multidimensional complex Euclidian spaces was given by Sheng Gong. Using the method of solid angular coefficient, the authors extend the Poincare-Bertrand formula on the complex sphere to the building domain of the complex biballs, and obtain a more general Poincare- Bertrand formula with the solid angular coefficients.

Oxide coating mechanism during fluidized bed reduction: solid-state reaction characteristics between iron ore particles and MgO

Experiments on the solid-state reaction between iron ore particles and MgO were performed to investigate the coating mechanism of MgO on the iron ore particles＇ surface during fluidized bed reduction. MgO powders and iron ore particles were mixed and compressed into briquettes and, subsequently, roasted at different temperatures and for different time periods. A Mg-containing layer was observed on the outer edge of the iron ore particles when the roasting temperature was greater than 1173 K. The concentration of Fe in the Mg-containing layer was evenly distributed and was approximately 10wt%, regardless of the temperature change. Boundary layers of Mg and Fe were observed outside of the iron ore particles. The change in concentration of Fe in the boundary layers was simulated using a gas–solid diffusion model, and the diffusion coefficients of Fe and Mg in these layers at different temperatures were calculated. The diffusion activation energies of Fe and Mg in the boundary layers in these experiments were evaluated to be approximately 176 and 172 k J/mol, respectively.