Diffusion Coefficient

Effect of Porosity on the Capacity Fade of a Lithium-Ion Battery. [Journal of The Electrochemical Society 151, A1104 (2004)]. Godfrey Sikha, Branko N. Popov, Ralph E. White. Abstract. ... In this model these values are measured from a commercial Sony US 18650 cell. ...

In this study an artificial neural network (ANN) model was developed to predict the oxidation behavior of magnesia graphite composites. After mechanism evaluation in different conditions, the kinetic parameters such as effective diffusion coefficient and diffusion activation energy of oxidation were calculated from ANN predicted results at different graphite content. The obtained mechanism and kinetic parameters were compared with experimental data.First of all, the reliability of the model was checked with different available data. It was found that the model results were in good agreement with experimental data prediction.The results showed that the main mechanism of oxidation was pore diffusion and effective diffusion coefficient as well as diffusion activation energy were comparable with previous works.Effective diffusion coefficient and diffusion activation energy which were calculated versus graphite content are in good agreement with experimental values.

Impedance of mixed conductors contacted with electrodes which are blocking for ions and reversible for electrons (or vice versa) is modelled phenomenologically. A closed form approximation is found which is valid in a very broad materials parameter window. The approximation is verified by the exact solution of Nernst–Planck–Poisson set of equations. The closed form results show that at low frequencies electrostatic as well as chemical relaxation occur. In particular, the closed form expression describes the transition from the 45° Warburg impedance to a 90° rise in the impedance spectra. In the former case the low frequency relaxation time bears information about the chemical diffusion coefficient while in the latter example information about the electrode capacitance is contained.

With the depletion of conventional crude oil reserves in the world, heavy oil and bitumen resources have great potential to meet the future demand for petroleum products. However, oil recovery from heavy oil and bitumen reservoirs is much more difficult than that from conventional oil reservoirs. This is mainly because heavy oil or bitumen is partially or completely immobile under reservoir conditions due to its extremely high viscosity, which creates special production challenges. In order to overcome these challenges significant efforts were devoted by Applied Research Center (ARC) at Florida International University and The Center for Energy Economics (CEE) at the University of Texas. A simplified model was developed to assess the density of the upgraded crude depending on the ratio of solvent mass to crude oil mass, temperature, pressure and the properties of the crude oil. The simplified model incorporated the interaction dynamics into a homogeneous, porous heavy oil reservoir ...

PACS. 05.40.-a – Fluctuation phenomena, random processes, noise, and Brownian motion. PACS. 45.70.Cc – Static sandpiles; granular compaction. PACS. 83.80.Fg – Granular solids. Abstract. – We study the stress profile of an ordered two-dimensional packing of beads in response to the application of a vertical overload localized at its top surface. Disorder is introduced through the Coulombic friction between the grains which gives some indeterminacy and allows the choice of one constrained random number per grain in the calculation of the contact forces. The so-called “multi-agent ” technique we use lets us deal with systems as large as 1000×1000 grains. We show that the average response profile has a double-peaked structure. At large depth z, the position of these peaks grows with cz, while their widths scales like Dz. c and D are analogous to “propagation ” and “diffusion ” coefficients. Their values depend on that of the friction coefficient µ. At small µ, we get c0 − c ∝ µ and D ∝ ...

We report numerical results on the repton model of Rubinstein [Phys. Rev. Lett. 59, 1946 (1987)] as adapted by Duke [Phys. Rev. Lett. 62, 2877 (1989)] as a model for the gel electrophoresis of DNA. We describe an efficient algorithm with which we have simulated chains of N reptons with N several hundred in some instances. The diffusion coefficient D

The Vapor Extraction (VAPEX) process, a newly developed Enhanced Oil Recovery (EOR) process to recover heavy oil and bitumen, has been studied theoretically and experimentally and is found a promising EOR method for certain heavy oil reservoirs. In this work, a simulation study ...

By internal oxidation of AgMg- and PdMg-alloys small precipitates ofMgO are formed within the Ag- or Pd-matrix. Thetotal area of the metal/oxide interface produced this way becomes severalsquare meters in one cubic centimeter of metal. Segregation of oxygen at theinterface is determined by desorption of gaseous oxygen for theAg/MgO-interface and by trapping of hydrogen for the Pd/MgO-interface. At673 to 873

... 06 Molar - - - . . A + A_) CB = 4.5 X 10 Molarr 3 ItS CC = 5.5 XIO0 MOlar 1. A I *- III - - , .1 .2 .3 .4 .5 0.2 0) _ n 1-/ a) E 0 -._ .0 0.1 0 0 a) -c 0 Tr (seconds) FIG. 1. Typical data points for Gi(T) at two values of CA, fitted by Eq. (6). Although ...

Fick’s model together with Arrhenius relationship were successfully used to evaluate water absorption of chickpea during soaking at a temperature range of 20–97 °C with 25 kHz 100 W, 40 kHz 100 W and 25 kHz 300 W ultrasound treatments. Use of ultrasound, increase in ultrasound power and soaking temperature significantly (P < 0.05) increased the water diffusion coefficient (Deff) of chickpea during soaking. Average gelatinization temperature of chickpea was found as 61.47 °C. Activation energy (Ea) values of chickpea for below and above gelatinization temperature were found to be 28.69 and 9.34 kJ mol−1, respectively. Ultrasound treatments significantly decreased the soaking time of chickpea.

It is shown that only 10% of the 99wt% water present in bacterial cellulose (BC) gels, produced by Acetobacter xylinum, behave like free bulk water; the majority of the water molecules in the gels is more or less tightly bound to the cellulose. The magnitude of the diffusion coefficients of ions transported in the water phase of the BC gels

The results of an analysis of velocity fluctuations in the plasma sheet of the Earth&#x27;s magnetotail measured onboard INTERBALL Tail Probe satellite are presented. The hodographs of the velocity in directions (Y, Z) and correlation functions are presented for a number of passages when the satellite was in the plasma sheet for a long time. The turbulent diffusion coefficients are calculated. A comparison of the obtained diffusion coefficients with those predicted theoretically in [1] is carried out. It is shown that the results of observations confirm theoretical predictions.

Adsorption of water vapour on wool provides not only textile comfort, but also convenience in transportation due to increase in its bulk density. The adsorption and desorption isotherms of water vapour for wool were determined by both volumetric technique using a Coulter Omnisorp 100CX instrument and gravimetric method employing a Cahn 2000 electronic microbalance. Adsorption isotherm fitting to B.E.T. model and hysteresis on desorption was observed. The average effective diffusion coefficient of water in wool was found to be 8.4 × 10-14 m2s-1 at 25°C from gravimetric data. The effects of packing height and air velocity on the breakthrough curves were also investigated in the wool packed columns. For pseudo first order model, k values changing between 0.33 × 10-6 − 69 × 10-6 s-1 was obtained for 2.2–6.4 cm s-1 air velocity and 0.05–0.20 m packing height ranges.