Number Of Moles Research Articles

A new four-phase adaptive implicit method for compositional reservoir simulation

Estimating oil and gas production from assets is essential to carry oil recovery processes. From the many techniques and tools used for such a task, the compositional simulation model is important for miscible displacement and problems with complex phase behavior. In this model, the fluid flow in porous media is described by a set of conservation equations. The solution of these problems involves spatial and time discretization schemes and approaches for handling the coupling of fluid flow and phase behavior. As a consequence, several solution algorithms arise from combining different selection of primary variables and equations, phase behavior decoupling techniques, and spatial/time discretization, which define the computational performance of these algorithms. In this work, a new Adaptive Implicit Method (AIM) is proposed by combining a global intensive variables Fully Implicit (FI) formulation and an IMPEC (IMplicit Pressure, Explicit Compositions) approach. In this approach, gridblocks are dynamically selected as FI or IMPEC based on a stability analysis algorithm. The fully implicit part considers pressure, water saturation, and overall compositions as primary variables and the IMPEC approach considers pressure and total number of moles for each component as primary variables. A new stability analysis algorithm is proposed and used for up to four-phases, but it is general enough to be used for any number of phases. The eigenvalues of the amplification matrix are used for the stability analysis and are computed using the Power's iteration method. The new approach is implemented in the in-house simulator called UTCOMPRS. The AIM formulation is compared to the fully implicit and IMPEC versions. We observed considerable improvement in the computational performance of UTCOMPRS with the new AIM when compared to the pure FI and IMPEC formulations.

THERMODYNAMIC ANALYSIS OF THE GAS MEDIUM IN THE FORMATION OF DIFFUSION COATINGS USING COMPOSITE SATURATING CHARGES

Review of the main processes of formation of diffuse coatings doped with molybdenum,vanadium and tungsten. The basic features of the formation of diffusion layers during chemicalthermaltreatment are considered.: When the SHS is tested, the container is heated to temperaturesof 1173-1330 K. Within 1-2 hours, a diffusion coating is formed due to the saturation of thesurface of structural materials with atoms of saturating elements - Cr, Al, V, Ti, B, W, Mo. Assaturating elements, the defects of these elements and the chemical compounds of these elementswere used, and to determine the possibility of using specific substances, chemical reactionswere considered that can occur in the temperature range of diffusion saturation usingSOS. It should be noted that the metallothermal Reduced oxide, which is used in the synthesisof powder media for CHT, is very fast. When obtaining diffuse layers using the composition ofsaturating the medium, a gas phase is formed, containing spolo-I, I2, I3, H, H2, H3, Cl2, Cl3 withchemical elements. With an increase in temperature, an increase in the amount of halides isobserved. This confirms the possibility of transferring alloying elements for the formation of diffusioncoatings. Also, the amount of products in the gaseous phase increases and condensedproducts are released. It is characteristic that in the temperature range of 700-1500 K, the decompositionof reaction products occurs during CHT, which is confirmed by the production ofdecomposition substances and a sharp increase in the number of gas moles.

A Composite Single Particle Lithium-Ion Battery Model Through System Identification

In the realm of lithium-ion (Li-ion) battery modeling, owing to its simplicity, the single particle model (SPM) has long been considered to be a promising reduced-order model (ROM) candidate to usher in the era of physics-inspired models (PIMs) in embedded applications. However, at high load currents, the standard SPM exhibits poor accuracies in computing the cell’s terminal voltage, thereby rendering it unsuitable as the plant model in state-estimation tasks. A comprehensive evaluation of the salient electrolyte-enhanced SPMs from the literature reveals that current solutions are either mathematically intractable or overly simplistic. For the ionic concentration in the electrolyte, the well-known quadratic approximation model, which straddles the boundary of computational complexity and mathematical tractability, reveals poor temporal performance, particularly at the current collector interfaces. In this work, we retain the spatial dynamics of the quadratic approximation model while proposing a novel approach using system identification techniques for its temporal dynamics. By employing linear approximations for the relevant subsystems, we identify discrete-time transfer functions of the debiased number of moles per unit area of lithium ions in the electrolyte within each electrode region, that yield improved spatio-temporal accuracies for the electrolyte concentration profile. We then augment the standard SPM with the new system identification-based electrolyte dynamics to arrive at an electrolyte-enhanced composite SPM (EECSPM). Finally, we demonstrate the superior performance of the EECSPM compared with the incumbent state of the art, thereby representing a concrete advancement toward the goal of using PIMs in real-time applications.

Quantitative Analysis of Solid Electrolyte Interphase and Its Correlation with The Electrochemical Performance of Lithium Ion Batteries Using Concentrated LiPF6/propylene Carbonate

The charge and discharge performance of graphite negative and LiNi0.5Co0.2Mn0.3O2 (NCM523) positive electrodes in highly concentrated 4.45 mol kg−1 LiPF6/propylene carbonate electrolyte solution was investigated to clarify the chemical species in the surface film formed on both electrode surfaces, and compared with those obtained with conventional 1 mol l−1 LiPF6/ethylene carbonate + dimethyl carbonate electrolyte solution. For the graphite negative electrode, the total electrons consumed to form surface film was well correlated with irreversible capacity, and total mole number and chemical species of the surface film were also correlated with interfacial resistance. In the conventional electrolyte solution, the reductive decomposition of solvents progressed preferentially, while LiPF6 decomposed to form surface film in the concentrated electrolyte solution. While both organic- and inorganic-based surface films can achieve high coulombic efficiency and high capacity retention over charge/discharge cycles, the inorganic-based surface film resulted in a significant increase in interfacial resistance. As for the NCM523 positive electrode in the concentrated electrolyte solution, the formation of inorganic-based surface film and a remarkable increase in interfacial resistance were observed clearly, as with the graphite electrode. However, there was no direct correlation among mole number of chemical species in surface films formed, their chemical composition and interfacial resistance.

Key design considerations for synthesis of mesoporous α-Li3V2(PO4)3/C for high power lithium batteries

In this article, we propose key design criteria to synthesis carbon coated α-Li3V2(PO4)3 positive electrode material for high power lithium batteries. A facile and scalable one-pot soft template method is adopted to synthesize α-Li3V2(PO4)3/C (LVP/C), which exhibits unique morphology of micron-size mesoporous secondary particles comprising interconnected primary nanoparticles showing good storage and rate performances with long cycle life. This cathode material displays high discharge capacities of 178, 90 and 59 mAh.g−1 at 0.1C, 30C and 80C, respectively. The mesoporous LVP/C with a 3D lithium diffusion network exhibits better rate performance (90 mAh.g−1 at 30C) as compared to the known phosphate, silicate or oxide cathode materials for lithium-ion batteries (LIBs). In addition, LVP/C electrode material retains 80% (at 1C) and 100% (at 20C) of its initial capacity after 1,000 cycles. The phase transitions during delitiation/litiation are discussed at different cutoff voltages, corresponding to the number of moles of lithium involved in the redox reactions. The reversibility of electrochemical extraction/insertion processes are confirmed using operando XRD measurements. Observed storage performances can be attributed not only to high crystallinity of LVP/C calcined at 800°C for 6 h; also to the unique mesoporous architecture of this carbon coated cathode material forming high packing density during the soft template synthesis. Obtained dense packed mesoporous architecture of LVP/C allows favourable (i) electrolyte wettability for lithium-incorporation from the electrolyte and (ii) long electronic wiring by the well-connected carbon coating towards the current collector.

Modeling confined fluids with the multicomponent potential theory of adsorption and the SAFT-VR Mie equation of state

In this work, the SAFT-VR Mie equation of state is used in conjunction with the Dubinin-Radushkevich-Astakhov (DRA) and Steele potentials, according to the Multicomponent Potential Theory of Adsorption (MPTA), to model the thermodynamic behavior of fluids confined in porous media. The problem specifications are the temperature, volume, and number of moles of each component, yielding a Helmholtz energy-minimization problem. Calculation results show very good agreement with experimental adsorption data for systems of methane, nitrogen, carbon dioxide, ethane, ethylene, and isobutane adsorbed on activated carbon and molecular sieve.

Students' understanding of molar concentration

This article presents and discusses the results of a study that investigates university students’ comprehension of the concept of molar concentration, following teaching and evaluation of the subject. The specific problems underlying learning of this concept have not yet been focused on in sufficient detail or depth. A “Reasoning with molarity” questionnaire, which explores the logical–mathematical relationships between the variables n, V and M, was administered to 303 Argentine first-year university students. Results obtained from think-aloud interviews related to this questionnaire, which were performed with 18 students, are also analysed. These results reveal that approximately half the first-year university students have no clear conceptual understanding of molarity. The main difficulty arises in inverse proportionality tasks where the number of moles (extensive) and M (intensive) should be related qualitatively to determine which solution occupies the smallest volume. It was also established that much conceptual confusion, such as the lack of differentiation between n and M, lies behind the algorithmic, numerical solution strategy carried out exclusively by many students.

Analysis of Brown and White Chicken Eggshells for Content of Calcium Carbonate

Background: An eggshell is the hard outer covering of an egg that serves to protect it from damage, microbial contamination and desiccation. The major component of the eggshell is calcium carbonate, which provides it with hardness and strength. Calcium carbonate content of eggshells contributes to the overall quality of the egg and eggs are an essential component of human and animal nutrition. Eggshells containing high calcium carbonate can also be processed and used as calcium supplement for bone and teeth health in vulnerable populations. Objectives: This study determined the calcium carbonate content of brown and white chicken eggshells sourced from Lagos markets and the effect of boiling on same. Materials and method: Eggs were sourced randomly from three markets in Lagos metropolis and the shells were washed and dried. The dry shells were pulverized and analyzed for calcium carbonate using the back titration method. Each sample (0.5 g) was reacted with excess 1.0 M HCl and the excess acid titrated with 0.1 M NaOH. The calcium carbonate content of each sample was calculated from the difference between the total number of moles of HCl used and that titrated as excess. Results: The results show that the eggshells studied have high calcium carbonate content and brown eggshells contained higher levels of calcium carbonate (95%) than white eggshells (91%). Boiling did not significantly reduce the calcium carbonate content of both brown and white eggshells. Eggshells from the three markets were similar in their content of calcium carbonate. Conclusion: This study shows that brown eggshells have a higher calcium carbonate content than white eggshells and boiling of eggs does not significantly reduce the calcium carbonate content of the shells.

Soybean Oil Treatment Using the Dissolving Curve Equation of Hydrogen.

The solubility of hydrogen in n-hexane was determined using a homemade reactor. The solubility of hydrogen in soybean oil was established using the Peng-Robinson (PR) equation of state and the van der Waals mixing rule. The curve equation established a linear relationship between the solubility of hydrogen in oil and the number of moles of hydrogen in the reactor. Under the optimal temperature and catalyst, the relationship between the hydrogen consumption of the hydrogenation of oil and fat and the TFAs formed in the oil was determined. When the reaction pressure exceeded 3.0 MPa, the hydrogenation of oil was consumed. The amount of hydrogen, the rate of hydrogenation, and the change in the TFAs all stabilized. Therefore, the pressure of the general hydrogenation reaction should not exceed 3.0 MPa. This result provides a quick and simple method for controlling TFAs in oils and fats for industrial applications.

Thermodynamic modeling of the gas-plasma phase in the processing of radioactive graphite in a gas plasma furnace

The method of thermodynamic modeling was used to determine composition and thermophysical properties of a gas-plasma phase of a system of radioactive graphite – water vapor in the temperature range from 1000 to 3200 K. It has been established that in the temperature range from 1000 to 1100 K, the main components of the gas-plasma phase are H2, CO, H2O, CO2, CH4. In the temperature range from 1100 to 2200 K – H2, CO, H2O, CO2. At temperatures from 2200 to 2600 K those are H2, CO, H2O, CO2, H. In the temperature range from 2600 to 3000 K those are H2, CO, H2O, CO2, H, OH. In the temperature range from 3000 to 3200 K those are H2, CO, H2O, H, CO2, OH, O, O2. The thermophysical properties of the system under consideration have been calculated: specific volume, entropy, enthalpy, total internal energy, number of moles in the system.

Determination of Molar Substitution of γ‐Hydroxypropyl Starch

AbstractA new class of hydroxypropyl starch, γ‐hydroxypropyl starch (γ‐HPS), is synthesized by using 3‐chloropropanol as the etherifying reagent. Two independent procedures for the determination of the number of moles of alkylene oxide combined per anhydroglucose unit (molar substitution, MS) in γ‐HPS are described. The feasibility of the Zeisel‐gas chromatographic technique and colorimetric determination are testified, and especially in the second approach, the stability and accuracy of dehydration process are also investigated. The concentrated sulfuric acid dehydration oxidation is replaced with 2‐iodoxybenzoic acid oxidation while retaining the same acid degradation and the same ninhydrin color reaction. Furthermore, the reliability and the range of application of the methods are tested by analyzing three samples of γ‐HPS and unmodified starch derivatives, and the results indicate that values of MS are in good agreement with each testing method.

Thermal decomposition, phase evolution and morphology study of combustion synthesized alumina powder – Influence of precursor pH

Here, nanocrystalline alumina powder is prepared by the glycine-nitrate combustion method, maintaining stoichiometric fuel to oxidizer ratio and two different pH conditions. The in-situ exothermic reaction occurs between an oxidizer, and fuel found to be affected by the alkalinity of the precursor solution. During combustion synthesis, spontaneous ignition occurs with the generation of gases and foamy ashes. The ash crushed into powders and then calcined at different temperatures. Thermodynamic modelling is done to calculate the enthalpy of combustions and the number of moles of gases released from the stoichiometric chemical reactions. Different characterization techniques used to study the phase formation, surface area, microstructure and morphology of the ash and calcined alumina powders. Fine crystalline α - Al2O3 powder with high surface area formed in alkaline condition. Micrographs reveal that flaky morphology of the alumina powder changed to grain type on increasing the pH of the precursor solution.

Inorganic Sulfur Species Formed upon Heterogeneous OH Oxidation of Organosulfates: A Case Study of Methyl Sulfate

Recent studies reveal that organosulfates at the particle surface can be oxidized by gas-phase OH radicals with significant rates. Inorganic sulfur species, such as the bisulfate ion (HSO4–) and sulfate ion (SO42–), can be formed upon these heterogeneous oxidation processes through the formation and subsequent reactions of sulfate radical anions (SO4•–) in the particle phase. However, the amount of inorganic sulfur species produced in these heterogeneous oxidation reactions is not known. We investigate the heterogeneous OH oxidation of sodium methyl sulfate (CH3SO4Na), the smallest organosulfate detected in atmospheric particles, using an oxidation flow reactor at a relative humidity of 75%. We quantify the kinetics by measuring the decay of CH3SO4Na and the amount of HSO4– and SO42– formed upon oxidation using ion chromatography. Kinetic measurements determine the heterogeneous OH reaction rate to be (5.72 ± 0.14) × 10–13 cm3 molecule–1 s–1, with an effective OH uptake coefficient, γeff, of 0.31 ± 0.06. The molar yield of inorganic sulfur species, defined as the total number of moles of HSO4– and SO42– formed per mole of CH3SO4Na consumed upon oxidation, is found to be significant and has an average value of 0.62 ± 0.18 upon oxidation. A kinetic model is developed to describe the kinetics and inorganic sulfur species formation upon oxidation. Model simulations suggest that CH3SO4Na tends to decompose rapidly into formaldehyde and SO4•–, and the reaction of SO4•– with CH3SO4Na plays a significant role in both governing the kinetics and the formation of inorganic sulfur species.

Enhancement of catalytic performance over MOF-808(Zr) by acid treatment for oxidative desulfurization of dibenzothiophene

The development of active oxidative desulfurization (ODS) catalysts is of practical importance. Recently, MOF-808(Zr) has been attempted to use as ODS catalyst due to its various advantages. However, generally MOF-808(Zr) prepared by conventional method was less active in the oxidation reactions due to the lack of defect sites in the structure. In this contribution, we report that the catalytic oxidative performance of MOF-808(Zr) can be enhanced by acid treatment due to the formation of defect sites resulting from the partial removal of organic linkers in the structure. During the experiment, the effect of acid concentration, treatment time, the addition amount of oxidant and reaction parameters on the performance of MOF-808(Zr) was studied. The catalytic results show that MOF-808(Zr) treated with 0.4 M HCl for 1h can catalyze the oxidation of dibenzothiophene completely at 60°C in 15 min. The activity (mole number of converted DBT per hour per unit mass) is 70 mmol h−1 g−1, which is much higher than that (45 mmol h−1 g−1) of parent MOF-808(Zr). In addition, the catalyst can be reused several times without obvious loss of catalytic performance.

Effect of kaolin and argillite mixtures on the dielectric properties of geopolymers

The use of geopolymer in radiofrequency applications and more precisely in antenna is innovative. The objective of this study is to highlight the impact of mixtures of kaolin and argillite on the structure and dielectric properties of geopolymers for antenna application. For this, six geopolymer formulations based on mixtures of kaolin and argillite with different proportions (33, 50 and 67%) and calcined at 600 and 750 ​°C were studied using mercury intrusion porosimetry, dielectric measurements and NMR spectroscopy. Low porosity values were obtained whatever the mixture. At 600 ​°C, the porosity increases with the increase of argillite content from 18 to 23%. At 750 ​°C, no impact of argillite content on the porosity (16%) was detected. However, the pore size increases with increasing the argillite content regardless of the calcination temperatures due to the unreacted secondary phases present in argillite. MAS-NMR experiments on geopolymer samples and calcined mixtures have evidenced a strong correlation between reactive aluminum resulting from dehydroxylation of kaolin and clay minerals of argillite and the geopolymerization rate. These structural variations influence the dielectric properties. Indeed, ε and tan ​δ values increase with the increase of argillite content and calcination temperature due to the increase in the number of moles of free alkali earth cations (Ca2+ and Mg2+).

A Comparison of CO2 and N2 Foaming Behaviors of PP in a Visualization System

Abstract Understanding of polypropylene (PP) foaming is critically important to reduce the weight of automotive parts. In this study, we used a batch foaming simulation system with visualization cell, to observe the foaming behaviors of PP that is blown with CO2 and N2 under various experimental conditions. We found that the nucleating agent content, initial temperature, pressure (i. e., gas content), and pressure drop rate during foaming have a significant effect on cell nucleation and cell growth. The cell density and the void fraction of PP foamed with CO2 and N2, respectively, were separately observed and compared. It was found that under the same experimental conditions, the maximum cell density of PP foamed with CO2 was higher than that of PP foamed with N2. However, the maximum cell density of PP foamed with CO2 was determined to be lower than that of PP foamed with N2, when the same gas mole numbers were employed. Based on the experimental results, optimum foaming conditions and effective processing strategies for PP-CO2 system are suggested.

Misconceptions in Rate of Reaction and their Impact on Misconceptions in Chemical Equilibrium

<p style="text-align:justify">Descriptive correlational research was conducted to discover misconceptions on Rate of Reaction (RR) that impact on Chemical Equilibrium (CE) misconceptions. This research was conducted to 245 eleventh-grade students of High School in Gowa, South Sulawesi, Indonesia, that have been studied the RR and CE topics. Misconceptions data were collected using three-tier tests and semi-structured interviews. The data were analyzed using descriptive and correlational analysis. Description of RR misconceptions that impact on CE misconceptions are determined with the percentage of students who consistently experience misconceptions about RR and CE. There were six misconceptions in RR that have an impact on CE, which are: Misconceptions related to changes in the reaction rate with time; The effect of temperature on the rate of reaction; The effect of adding catalysts to the activation energy; and the mathematical affect relating to the rate of reaction and number of moles. Misconceptions in RR and CE have 0.39 correlation coefficient, based on Spearman's formula. These results indicate that the impact of misconception in RR on CE is moderate. This study suggests that education practitioners should eliminate the misconception of prerequisite concepts before teaching the next related concepts.</p>

State function‐based flash specifications for open systems in the absence or presence of chemical reactions

AbstractDiverse engineering fields require flash calculations like isothermal flash, isenthalpic flash, and isentropic flash. They can be cast as minimization of a thermodynamic state function and solved by Michelsen's Q‐function approach. Flash calculations for open systems, that is, systems where chemical potentials are specified instead of the mole numbers for some components, also belong to this scope. By analyzing the construction of Q‐functions through Legendre transforms, we extend this approach to the flash for open systems in the absence or presence of chemical reactions, resulting in general formulations for various specifications. For systems without reactions, the classical framework using mole numbers as independent variables is employed; for those with reactions, the modified‐RAND framework is employed. We present examples for open systems at constant temperature and pressure. Using the Q‐function minimization, we can solve multicomponent nonreactive or reactive systems at a specified chemical potential with quadratic convergence over a wide range of conditions.

Влияние состава природного газа на тепловой коэффициент полезного действия отражательной печи для никелевых сплавов

The purpose of the article is to develop and substantiate the principles of an energy model of an industrial reverberatory furnace taking into account chemical composition and properties of natural gas as well as to calculate the furnace thermal efficiency in order to estimate its industrial performance. To conduct the research mathematical calculations are performed based on the data of chemical and physical analysis of flue gases and chimney temperature using standard graphs of excess air and enthalpy values of flue gas components. The measurement of the amount of waste pollutants is carried out using MRU Delta 65-3 gas analyzers, which identify the total amount of gases (O2, CO, NO, H2S) They determine the temperature, pressure (vacuum), calculate the content of CO2 and installation efficiency as well. Aspen Hysys program is used to verify the mathematical model. The data on the properties of natural gas are obtained including the data on chemical composition, molecular weight, calorific value, excess air during combustion. The data on flue gases are also obtained, which include the data on the burnt gas components, molecular weights, enthalpy, calorific value, flue gases ratio at the temperatures from 94°C to 316°C. The chemical reactions of combustion given with the number of moles required and formed for each reaction are used to calculate the thermal efficiency of a reverberatory furnace for nickel alloys. The calculated data are confirmed by Aspen Hysys software. Based on the studies conducted, it is found that the variable having the greatest influence on the thermal efficiency is the low calorific value, since it depends on the composition of the natural gas. The proposed methods for calculating the thermal efficiency using a computer program are effective if an operator wants to evaluate the furnace operation efficiency on site.

Prediction of remaining useful life for a composite electrode lithium ion battery cell using an electrochemical model to estimate the state of health

The objective of this paper is development of a remaining useful life (RUL) prediction algorithm based on estimation of parameters of an enhanced single particle model (eSPM) that could be implemented using vehicle charging data. First, we use data from an aging study conducted on LMO-NMC-cathode graphite-anode battery cells to develop an eSPM that can predict the evolution of parameters associated with the aging of the battery. In particular, the parameters we estimate in this work as indicators of state of health (SOH) are number of moles of cyclable lithium and Ohmic resistance. A method is demonstrated for estimating these parameters from experimental data, and it is shown that they are correlated with battery SOH measured from the experimental aging study. Finally, a composite SOH metric derived from the estimated eSPM parameters is used to design a RUL predictor based on a particle filter (PF) that can predict the RUL utilizing the evolution of the SOH metric. The RUL estimation algorithm is validated using experimental data collected on several LMO-NMC battery cells, showing that it is possible to infer battery SOH and RUL from charging data readily available in plug-in battery-electric or hybrid vehicles.