scholarly journals Multicomponent mixing on the “diffusion – convection” transition boundary at elevated pressures

2022 ◽  
Vol 2150 (1) ◽  
pp. 012014
Author(s):  
V N Kossov ◽  
O V Fedorenko ◽  
M Zhaneli ◽  
K Mukhatova

Abstract An experimental and theoretical study of three-component mixing at the “diffusion – convection” boundary at elevated pressures is carried out. It is shown that the pressure dependence of the dimensionless parameter α, defined as the ratio of the experimental values of the component concentrations to those calculated by the Stefan-Maxwell equations, has characteristic regions due to the interaction of structural formations moving towards each other, in which a transition from one critical motion to another occurs. Within the framework of a linear analysis of the stability of a ternary gas mixture for a vertical circular cylinder channel, it is shown that scale perturbations determining the transition from one type of flow to another correspond to a certain value of the perturbation mode n and the critical Rayleigh numbers.

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 50
Author(s):  
Barbara D. Weiß ◽  
Michael Harasek

This review studies unwanted precipitation reactions, which can occur in SO2 absorption processes using a magnesium hydroxide slurry. Solubility data of potential salts in the MgO-CaO-SO2-H2O system are evaluated. The reviewed data can serve as a reliable basis for process modeling of this system used to support the optimization of the SO2 absorption process. This study includes the solubility data of MgSO3, MgSO4, Mg(OH)2, CaSO3, CaSO4, and Ca(OH)2 as potential salts. The solubility is strongly dependent on the state of the precipitated salts. Therefore, this review includes studies on the stability of different forms of the salts under different conditions. The solubility data in water over temperature serve as a base for modeling the precipitation in such system. Furthermore, influencing factors such as pH value, SO2 content and the co-existence of other salts are included and available data on such dependencies are reviewed. Literature data evaluated by the International Union of Pure and Applied Chemistry (IUPAC) are revisited and additional and newer studies are supplemented to obtain a solid base of accurate experimental values. For temperatures higher than 100 °C the available data are scarce. For a temperature range from 0 to 100 °C, the reviewed investigations and data provide a good base to evaluate and adapt process models for processes in order to map precipitations issues accurately.


2013 ◽  
Vol 12 (06) ◽  
pp. 1350045 ◽  
Author(s):  
ANURAG SRIVASTAVA ◽  
BODDEPALLI SANTHIBHUSHAN ◽  
PANKAJ DOBWAL

The present paper discusses the investigation of electronic properties of anthracene-based single electron transistor (SET) operating in coulomb blockade region using Density Functional Theory (DFT) based Atomistix toolkit-Virtual nanolab. The charging energies of anthracene molecule in isolated as well as electrostatic SET environments have been calculated for analyzing the stability of the molecule for different charge states. Study also includes the analysis of SET conductance dependence on source/drain and gate potentials in reference to the charge stability diagram. Our computed charging energies for anthracene in isolated environment are in good agreement with the experimental values and the proposed anthracene SET shows good switching properties in comparison to other acene series SETs.


2014 ◽  
Vol 87 (10) ◽  
pp. 1116-1123 ◽  
Author(s):  
Abolfazl Azizi ◽  
Ali Ebrahimi ◽  
Mostafa Habibi-Khorassani ◽  
Shiva Rezazadeh ◽  
Roya Behazin

2014 ◽  
Vol 33 (7) ◽  
pp. 1845-1850 ◽  
Author(s):  
Xuerui Wang ◽  
Congqing Zhu ◽  
Haiping Xia ◽  
Jun Zhu

2021 ◽  
Vol 37 (4) ◽  
pp. 805-812
Author(s):  
Ahissandonatien Ehouman ◽  
Adjoumanirodrigue Kouakou ◽  
Fatogoma Diarrassouba ◽  
Hakim Abdel Aziz Ouattara ◽  
Paulin Marius Niamien

Our theoretical study of stability and reactivity was carried out on six (06) molecules of a series of pyrimidine tetrazole hybrids (PTH) substituted with H, F, Cl, Br, OCH3 and CH3 atoms and groups of atoms using the density function theory (DFT). Analysis of the thermodynamic formation quantities confirmed the formation and existence of the series of molecules studied. Quantum chemical calculations at the B3LYP / 6-311G (d, p) level of theory determined molecular descriptors. Global reactivity descriptors were also determined and analyzed. Thus, the results showed that the compound PTH_1 is the most stable, and PTH_5 is the most reactive and nucleophilic. Similarly, the compound PTH_4 is the most electrophilic. The analysis of the local descriptors and the boundary molecular orbitals allowed us to identify the preferred atoms for electrophilic and nucleophilic attacks.


2017 ◽  
Vol 26 (46) ◽  
Author(s):  
Víctor Mendoza-Estrada ◽  
Melissa Romero-Baños ◽  
Viviana Dovale-Farelo ◽  
William López-Pérez ◽  
Álvaro González-García ◽  
...  

In this research, first-principles calculations were carried out within the density functional theory (DFT) framework, using LDA and GGA, in order to study the structural, elastic, electronic and thermal properties of InAs in the zinc-blende structure. The results of the structural properties (a, B0, ) agree with the theoretical and experimental results reported by other authors. Additionally, the elastic properties, the elastic constants (C11, C12 and C44), the anisotropy coefficient (A) and the predicted speeds of the sound ( , , and ) are in agreement with the results reported by other authors. In contrast, the shear modulus (G), the Young's modulus (Y) and the Poisson's ratio (v) show some discrepancy with respect to the experimental values, although, the values obtained are reasonable. On the other hand, it is evident the tendency of the LDA and GGA approaches to underestimate the value of the band-gap energy in semiconductors. The thermal properties (V, , θD yCV) of InAs, calculated using the quasi-harmonic Debye model, are slightly sensitive as the temperature increases. According to the stability criteria and the negative value of the enthalpy of formation, InAs is mechanically and thermodynamically stable. Therefore, this work can be used as a future reference for theoretical and experimental studies based on InAs.


2005 ◽  
Vol 2005 (2) ◽  
pp. 169-193 ◽  
Author(s):  
M. Belk ◽  
B. Kazmierczak ◽  
V. Volpert

Existence of reaction-diffusion-convection waves in unbounded strips is proved in the case of small Rayleigh numbers. In the bistable case the wave is unique, in the monostable case they exist for all speeds greater than the minimal one. The proof uses the implicit function theorem. Its application is based on the Fredholm property, index, and solvability conditions for elliptic problems in unbounded domains.


1997 ◽  
Vol 11 (16) ◽  
pp. 1959-1967 ◽  
Author(s):  
R. Asokamani ◽  
R. Mercy Amirthakumari ◽  
G. Pari

The self-consistent scalar relativistic band structure for AgGaX 2 (X = S, Se, Te) performed in chalcopyrite structure using the TBLMTO method at various pressures are reported here. Empty spheres were introduced in the calculations as the chalcopyrite structure is loosely packed. From the total energy calculations, the equilibrium lattice constant and the bulk modulus at zero pressure were calculated and these values agree well with the reported experimental values. All these compounds are found to have direct energy gap at ambient pressure with the gap widening with increased pressures which are in agreement with the experimental results. The deformation potential, dE g /dP for the compounds are also reported here. The metallisation volumes are calculated and the possibility of observing superconductivity in these compounds is discussed.


1980 ◽  
Vol 102 (3) ◽  
pp. 344-349 ◽  
Author(s):  
M. A. Hoffman ◽  
R. K. Takahashi ◽  
R. D. Monson

Experiments have been performed to determine the length for convergence or closure of a vertical, hollow annular water jet due to the action of surface tension forces. The data agree well with theoretical predictions up to the maximum velocity where reliable data could be obtained (4.4 m/s). These experiments extend the range of confirmation of the theories in terms of the dimensionless parameter, Nc ≡ We/Fr2, from about 0.01 to over 100. The stability of the annular jet subjected to natural and external disturbances is also discussed briefly. Finally the results of a series of experiments on the flow spreading or splitting due to the presence of wedge-shaped obstacles in the path of the annular jet flow are presented.


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