Papers by Keyword: Chemical Reaction

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Authors: Ahmed Benzaoui, Najla El Gharbi
Abstract: Intense research on development of ozone and global warming protection heat pump machine technology is observed, because of the international environment protection. In arid areas, electricity network is not often available or it is at high price while the sun is shining and the cooling demand is important during almost the year. Absorption refrigeration has been intensively investigated over the world, during the last twenty years. This report is concerned by the solar energy conversion and use in an absorption cooling process where a specific porous medium is used to improve the efficiency. This process is the best appropriate solution to refrigeration and air conditioning problems in the desert areas and other remote countries where electricity power network is not available. The simulation of absorbing/desorbing chemical reaction in a solar cooling system, working according to absorption principle has given some results allowing to confirm the efficiency improve, the economical and technical feasibility and to avoid difficulties.
594
Authors: K. Avinash, N. Sandeep, Oluwole Daniel Makinde, Isaac Lare Animasaun
Abstract: This study covers a numerical investigation of gyrotactic microorganisms contained MHD flow over a vertical plate bearing thermal radiation, thermophoresis, Brownian motion, chemical reaction and inclined magnetic field effects. With the assistance of similarity transforms, the derived governed equations are transformed as set of ODEs and solved numerically by R-K and Newton’s methods. Graphs are exhibited and explained for various parameters of interest. For engineering interest, we mainly talked about the Skin friction coefficient, reduced Sherwood, Nusselt numbers and density of motile microorganisms. We noticed a rise in the heat transfer rate of motile microorganisms for rising values of the thermophoresis and Brownian motion parameters. Increasing values of the aligned angle hikes the drag force.
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Authors: Yu Long Xu, Chuan Shou Sun, Guo Hua Liu
Abstract: A convenient method for the preparation of imidazolium salts-functionalized mesoporous catalyst Me-Bmim-SBA-15 (2) by postgrafting [bmIm]OH on SBA-15 was developed. This catalyst presented excellent catalytic activities (more than 96% yields for all tested aldehydes) for Knoevenagel condensation of aldehydes and ethyl cyanoacetate under microwave irradiation in solid medium. Of particular note is that such a catalyst could be readily recovered and reused in the consecutively catalytic runs (up to 10 uses) while maintained high catalytic activity.
1944
Authors: Kassem Alassaad, Véronique Soulière, François Cauwet, Davy Carole, Gabriel Ferro
Abstract: The interaction of liquid Ge and Si droplets, deposited by CVD, on the surface of 4H-SiC single-crystals is studied. It was found that at 1500 °C Ge forms micrometric droplets while Si forms nanometric dots. While the Si dots do not seem to interact significantly with SiC, the Ge droplets have the tendency to dissolve the Si from the seed. This mechanism not only happens during deposition but also during the cooling. If the cooling rate is too slow, Ge evaporates from the droplets while dissolving Si so that, at the end, the droplets look like to have been fully converted from Ge to Si.
121
Authors: Ram Prakash Sharma, Oluwole Daniel Makinde, Isaac Lare Animasaun
Abstract: In this paper, the problem of unsteady magnetohydrodynamic free convective flow with thermal radiation and chemical reaction past a porous vertical plate moving through a binary mixture in an optically thin environment is investigated. The viscosity of the fluid is assumed to vary linearly with temperature. Due to the nature of corresponding dimensionless variable for temperature and its boundary condition as in the case of binary mixture, Boussinesq approximation and temperature dependent viscosity model were modified. The governing boundary layer equations are transformed using suitable similarity transformation and solved numerically. A parametric study of selected parameters is conducted and results for velocity, temperature, concentration, local skin friction coefficient, local Nusselt number and local Sherwood number are illustrated and physical aspects of the problem are discussed. Increasing the temperature dependent variable fluid viscosity leads to increase in the velocity of the fluid and heat transfer rate at the surface when Grashof related parameters are greater than one-tenth.
308
Authors: Qian Zhang, Hong Hong Sun, Jiu Guang Geng
Abstract: Asphalt aging occurs both in the construction period and in the service period of asphalt pavement. It is believed that aging could have a big influence on the rheological mechanical and adhesion characteristics of the asphalt. Asphalt aging is a process associated with a lot of factors as heat, rays, oxygen, and ozone. In the aging process, some chemical compositions of asphalt are subject to be activated by these factors and undergo some chemical changes. A theoretical analysis at a chemical reaction level to the asphalt aging mechanism is presented in this paper. Asphalt aging can be sorted as thermal oxidation aging, ray oxidation aging, and ozone oxidation aging. The thermal oxidation aging usually occurs in the components with chains and double bonds in their molecules. The ray oxidation aging can be found in components with one carbonyl or more carbonyls. Those components with a π key in their molecular structures are prone to the ozone oxidation aging.
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Authors: S. Mohammed Ibrahim, Prathi Vijaya Kumar, Oluwole Daniel Makinde
Abstract: The principle priority of this study is to inspect the performance of two dimensional chemically reacting non-Newtonian fluid bearing Soret, Dufour, thermal radiation, heat source and slip effects. The flow is prompted by a slendering surface with variable thickness. Casson and Williamson fluid models are incorporated in this discussion. Governing equations are evolved and converted into ordinary differential equations using similarity transformations. We adopted homotopy analysis method (HAM) to pick up the solutions. The graphical and tabular results for velocity, temperature, concentration, skin friction factor, local Nusselt number and Sherwood number are secured for both Casson and Williamson fluids. The correspondence between the acquired and previous results reveals that they are in good correlation. It is found that there is a significant increase in the thermal boundary layer thickness when the strength of the Dufour number is increased.
319
Authors: R. Suresh Babu, B. Rushi Kumar, Oluwole Daniel Makinde
Abstract: This article investigates the magnetohydrodynamic mixed convective heat, and mass transfer flow of an incompressible, viscous, Boussinesq, electrically conducting fluid from a vertical plate in a sparsely packed porous medium in the presence of thermal radiation and an nth order homogeneous chemical reaction between the fluid and the diffusing species numerically. In this investigation, the fluid and porous properties like thermal and solutal diffusivity, permeability and porosity are all considered to be vary. The governing non-linear PDE's for the fluid flow are derived and transformed into a system of ODE's using an appropriate similarity transformation. The resultant equations are solved numerically using shooting technique and Runge-Kutta integral scheme with the help of Newton-Raphson algorithm in order to know the characteristics of the fluid for various non-dimensional parameters which are controlling the physical system graphically. The results of the numerical scheme are validated and a numerical comparison has been made with the available literature in the absence of some parameters and found that in good agreement. Nomenclature
332
Authors: Oluwole Daniel Makinde, S.R. Mishra
Abstract: In this paper, the combined effects of magnetic field, buoyancy forces, nth order chemical reaction, heat source, viscous dissipation, Joule heating and variable viscosity on mixed convection Blasius flow of a conducting fluid over a convectively heated permeable plate embedded in a porous medium is investigated. The fluid properties are assumed to be constant except for the density variation with the temperature and reacting chemical species concentration. The nonlinear governing differential equations were obtained and solved numerically using the Runge-Kutta-Fehlberg method with shooting technique. The dimensionless velocity, temperature and concentration profiles are shown graphically. The effects of pertinent parameters on the skin friction, Nusselt number and Sherwood number are examined. It is found that skin friction decreases while Nusselt number and Sherwood number increase with a decrease in the fluid viscosity in the presence of magnetic field.
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