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Couto N.,Royal University | Couto N.,University of Porto | Silva V.,Royal University | Silva V.,University of Porto | And 9 more authors.
Applied Thermal Engineering | Year: 2015

As the quantity of municipal solid waste (MSW) increases with economic growth, problems arise in regard to sustainable management solutions. Thermal treatment presents a valid option for reducing the amounts of post-recycling waste to be landfilled. Incineration technology, besides reducing the total volume of waste and making use of the chemical energy in MSW for power generation, has negative environmental impact from high emission of pollutants. Recent policy to tackle climate change and resources conservation stimulated the development of renewable energy and landfill diversion technology, thereby giving gasification technology development renewed importance. In this work a two-dimensional CFD model for MSW gasification was developed and an Eulerian-Eulerian approach was used to describe the transport of mass, momentum and energy for the solid and gas phases. This model is validated using experimental data from the literature. The numerical results obtained are in good agreement with the reported experimental results. © 2014 Elsevier Ltd. All rights reserved.

Aljarrah M.,Zarqa University | Essadiqi E.,University Internationale Of Rabat
International Review of Mechanical Engineering | Year: 2012

The effect of alloying elements (Ca and Ca+Ce) on the solidification microstructure of AZ31 alloy has been investigated using optical microscopy and thermodynamic calculations. The effect of cooling rate on grain size of the studied alloys, in the as-cast, as-hot and postannealing conditions, were examined. Degassing of AZ31 alloy using (C 2Cl 6) tablet releases carbon which reacts with aluminum in the molten metal and forms high stable aluminum carbide phase (Al 4C 3). The precipitation of Al 4C 3 particles act as nuclei and refine the microstructure. It has been found that alloying AZ31 with Ca and Ca+Ce shows promising potentials in grain refinement by precipitating stable compounds. Secondary dendrite arm spacing (SDAS) and grain size of the ascast AZ31alloys were investigated with respect to cooling rate and, Ca and Ca+Ce additions. Experimental relationship between cooling rate and SDAS has been established. © 2012 Praise Worthy Prize S.r.l. - All rights reserved.

Grosdidier B.,University of Lorraine | Ben Abdellah A.,University of Lorraine | Ben Abdellah A.,Abdelmalek Essaadi University | Ben Abdellah A.,University Internationale Of Rabat | And 3 more authors.
Physica B: Condensed Matter | Year: 2015

The Mn66Ga34 alloy at this particular composition is known to be zero alloy in which the linear combination of the two neutron scattering lengths weighted by the atomic compositions vanish. Thus for this specific concentration, the effect of the partial structure factors SNN and SNC is cancelled by a weighted term, which value is zero. Then the measured total structure factor S(q) gives directly the concentration-concentration structure factor SCC(q). We present here the first experimental results of neutron diffraction on the Mn66Ga34 "null matrix alloy" at 1050 °C. The main peak of the experimental SCC(q) gives a strong evidence of a hetero-atomic chemical order in this coordinated alloy. This order also appears in real space radial distribution function which is calculated by the Fourier transform of the structure factor. The degree of hetero-coordination is discussed together with other manganese-polyvalent alloys. However manganese also shows abnormal magnetic scattering in the alloy structure factor which must be corrected. This correction gives an experimental information on the mean effective spin of manganese in this liquid alloy. We present the first critical theoretical calculations of the magnetic correction factor in Mn-Ga zero-alloy based on our accurate experimental measurements of SCC(q). © 2015 Published by Elsevier B.V.

Aydin H.,McGill University | Essadiqi E.,University Internationale Of Rabat | Jung I.-H.,McGill University | Yue S.,McGill University
Materials Science and Engineering A | Year: 2013

In this paper, four different steel compositions, centered on Mn as the main alloying element, are designated as candidates for Third Generation AHSS grades. The design of these steels is based on controlling the deformation behavior of the retained austenite. Thus, heat treatment process parameters are determined in order to obtain different amounts and morphologies of retained austenite. The evolution of the microstructure, during processing as well as deformation, is characterized by using optical, electron microscopy techniques and mechanical tests. The effect of alloy composition and processing parameters on the deformation mechanisms of these steels is discussed. © 2012 Elsevier B.V.

Essehli R.,Qatar Environment and Energy Research Institute | Belharouak I.,Qatar Environment and Energy Research Institute | Ben Yahia H.,Qatar Environment and Energy Research Institute | Chamoun R.,Qatar Environment and Energy Research Institute | And 5 more authors.
Dalton Transactions | Year: 2015

A new orthophosphate α-Na2Ni2Fe(PO4)3 was synthesized using a solid state reaction route, and its crystal structure was determined from powder X-ray diffraction data. The physical properties of α-Na2Ni2Fe(PO4)3 were studied by magnetic and electrochemical measurements and by Mössbauer and Raman spectroscopy. α-Na2Ni2Fe(PO4)3 crystallizes according to a stuffed α-CrPO4-type structure with the space group Imma and the cell parameters a = 10.42821(12), b = 13.19862(15), c = 6.47634(8) Å, and Z = 4. The structure consists of a 3D-framework of octahedra and tetrahedra sharing corners and/or edges with channels along [100] and [010], in which the sodium atoms are located. The 57Fe Mössbauer spectrum indicates that the Fe3+ cation is distributed over two crystallographic sites implying the presence of a Ni2+/Fe3+ statistical disorder. Magnetic susceptibility follows the Curie-Weiss behavior above 100 K with θ = -114.3 K indicating the occurrence of predominant antiferromagnetic interactions. Electrochemical tests indicate that during the first discharge to 1 V vs. Na+/Na in a sodium cell, one Na+ ion could be inserted into the α-Na2Ni2Fe(PO4)3 structure. This has led to the formation of a new phase Na3Ni2Fe(PO4)3 which was found to be promising as a positive electrode material for sodium batteries. When α-Na2Ni2Fe(PO4)3 is further discharged to 0.03 V, it delivers a capacity of 960 mA h g-1. This corresponds to the intercalation of more than seven sodium atoms per formula unit which is an indication of a conversion-type behaviour with the formation of metallic Fe and Ni. When cycled in the voltage range 0.03-3 V vs. Na+/Na, at 20 °C, under the current rates of 50, 100, 200, and 400 mA g-1, reversible capacities of 238, 196, 153, and 115 mA h g-1, were obtained, respectively. This journal is © The Royal Society of Chemistry 2015.

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