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Numerical study of parameters affecting pressure drop of power-law fluid in horizontal annulus for laminar and turbulent flows

Hicham Ferroudji, Ahmed Hadjadj, Ahmed HADDAD, Titus Ntow Ofei  (2019)
Publication

Efficient hydraulics program of oil and gas wells has a crucial role for the optimization of drilling process. In the present paper, a numerical study of power-law fluid flow through concentric (E = 0.0) and eccentric annulus (E = 0.3, E = 0.6 and E = 0.9) was performed for both laminar and turbulent flow regimes utilizing a finite volume method. The effects of inner pipe rotation, flow behavior index and diameter ratio on the pressure drop were studied; furthermore, the appearance and development of secondary flow as well as its impact on the pressure drop gradient were evaluated. Results indicated that the increment of the inner pipe rotation from 0 to 400 rpm is found to decrease pressure drop gradient for laminar flow in concentric annulus while a negligible effect is observed for turbulent flow. The beginning of secondary flow formation in the wide region part of the eccentric annulus (E = 0.6) induces an increase of 9% and a slight increase in pressure drop gradient for laminar and turbulent flow, respectively. On the other hand, the variation of the flow behavior index and diameter ratio from low to high values caused a dramatic increase in the pressure drop. Streamlines in the annulus showed that the secondary flow is mainly induced by eccentricity of the inner pipe where both high values of diameter ratio and low values of flow behavior index tend to prevent the secondary flow to appear. Voir les détails

Mots clés : Computational fluid dynamics (CFD) Power-law fluid Pressure drop Secondary flow

EFFECT OF filler METAL types ON MICROSTRUCTURE AND MECHANICAL BEHAVIOR OF HSLA-X70/304L SS DISSIMILAR WELDS

Mohammed Farid BENLAMNOUAR, Mohamed HADJI, Riad BADJI, Nabil Bensaid, Tahar Saadi, Yazid LAIB LAKSIR, Sabah Senouci  (2019)
Article de conférence

The aim of this study is to investigate the effect filler metal types on microstructure and mechanical properties of dissimilar welds between HSLA-X70 high strength steel alloy and 304L austenitic stainless steel produced by automatic tungsten arc welding (TIG). The weld joints were prepared using E304L, E316L, E2209L, and E7010 filler metal. The mechanical characteristics obtained from hardness, tensile and impact testing, were correlated to the optical and SEM microscopy, to establish a relationship between filler metal composition and the microstructures in different weld regions. It is concluded that E2209 filler metal lead to improve in the resilience characteristics and tenacity with a slight reduction in the ultimate tensile strength and hardness. Voir les détails

Mots clés : Dissimilar weld, HSLA-X70, 304L, microstructure, Mechanical property

Optimization of TIG Welding Process Parameters for X70-304LDissimilar Joint Using Taguchi Method

Mohamed Farid Benlamnouar, Mohamed HADJI, Riad BADJI, Nabil Bensaid, Tahar Saadi, Yazid Laib dit Laksir, Sabah Senouci  (2019)
Publication

The optimization of mechanical properties of the welded joints requires a statisticalapproach such as Taguchi experimental designs associated with experimental techniques andlaboratory characterizations. The aim of this work is to propose a method of optimization of themechanical performances of a TIG dissimilar welding of two grades of steels: a high strength lowalloy steel X70 and an austenitic stainless steel 304L. The experimental designs were chosenaccording to the Taguchi method L9. The metallurgical characterization includes opticalmicroscopy, SEM microscopy, EDX analyses and mechanical tests to establish a relationshipbetween welding parameters, microstructures and mechanical behavior in different dissimilar weldregions. The results showed that the hardness is more strongly related to microstructural evolutionthan tensile strength of dissimilar joint. It was found that gas flow is the main significant TIGwelding parameter affecting dissimilar weld characteristics. Voir les détails

Mots clés : hardness, tensile test, ANOVA, Dissimilar welds, Taguchi method

Annealing duration influence on dip-coated CZTS thin films properties obtained by sol-gel method

M.C. Benachour, R. Bensaha, R. Moreno  (2019)
Publication

The effect of annealing duration on structural and optical properties of dip-coated crystallineCZTS thin films was studied. The obtained samples were investigated by several techniques suchas XRD, Raman spectroscopy, SEM, UV–vis spectroscopy and Photoluminescence. Being con-firmed by Raman spectroscopy, XRD analysis reveals the formation of kesterite tetragonal phasewith preferential orientation along (112) direction. The grain size tends to increase as the an- nealing duration increases, a result confirmed by SEM. The last shows smooth, uniform, homo-geneous and densely packed grains. Optical measurement analysis reveals that layers have re- latively high absorption coefficient in the visible spectrum with a band gap reduction of1.62−1.50 eV which is quite close to the optimum value for a solar cell. The photoluminescence distinguishes broad bands that have maximums of intensity limited between 1.50 and 1.62 eV,corresponding to the optical band gap of the CZTS.Kesterite,Sol-gel,Thin-film,Dip-coating,CZTS,Photoluminescence Voir les détails

Mots clés : Kesterite, sol-gel, Thin-film, Dip-Coating, CZTS, Photoluminescence

Annealing duration in?uence on dip-coated CZTS thin ?lms properties obtained by sol-gel method

M. C. Benachour, R. Bensaha, R. Morenoc  (2019)
Publication

The e?ect of annealing duration on structural and optical properties of dip-coated crystallineCZTS thin ?lms was studied. The obtained samples were investigated by several techniques suchas XRD, Raman spectroscopy, SEM, UV–vis spectroscopy and Photoluminescence. Being con-?rmed by Raman spectroscopy, XRD analysis reveals the formation of kesterite tetragonal phasewith preferential orientation along (112) direction. The grain size tends to increase as the an- nealing duration increases, a result con?rmed by SEM. The last shows smooth, uniform, homo-geneous and densely packed grains. Optical measurement analysis reveals that layers have re- latively high absorption coe?cient in the visible spectrum with a band gap reduction of1.62−1.50 eV which is quite close to the optimum value for a solar cell. The photoluminescence distinguishes broad bands that have maximums of intensity limited between 1.50 and 1.62 eV, corresponding to the optical band gap of the CZTS. Voir les détails

Mots clés : Kesterite, sol-gel, Thin films, Dip-coating CZTS, Photoluminescence

Elaboration et caractérisation des couches minces de TiO2dopées à l’erbium, à différentes températures et épaisseurs

BENACHOUR Med Cherif (2011)
Mémoire de magister

This study is to develop and characterize thin films of titanium oxide (TiO2) dopedwith different erbium content (5, 7 and 10% by volume) and processed in a temperature range400-500 ° C. obtained by the sol-gel. These thin films are deposited on glass substrates andporous silicon. We have demonstrated the influence of the thickness, the rate of dopant andannealing temperature on optical properties, structural and thermal properties of thin films andxerogels. For this, various investigative techniques were used: DSC, XRD, Ramanspectroscopy, scanning electron microscope (MEB), atomic force microscopy (AFM) andUV-visible spectroscopy.The results obtained by DSC show that the doping of TiO2 with erbium produces afirst shift conversion of TiO2 to the low temperatures of 338 ° C to 260 ° C. So doping witherbium leads to an early acceleration of the crystallization of titanium oxide compared to theundoped state. For cons, the same addition of 5%, 7% and 10% of Er 3 + also causes a shift ofthe second transformation to the high temperatures of 357 ° C to 383 ° C. So it causes a delayof crystallization, but the formation of other phases.The DRX of thin films show the one hand, the addition of 5%, 7% and 10% of Er in thematrix of TiO2 causes in addition to the training phase of anatase and brookite, the presenceof other phases: Rutile, Er2Ti2O7, Er2TiO5, Er2O3 and secondly, the Raman spectrumconfirms these results.The SEM micrographs show that the thin layer is homogeneous and free fromcracking. They reveal a nanostructuring of thin layer which consists of nano grains consistentwith the sizes. While the AFM images show that they are composed of many nanocrystalswith high density on the substrate. The size of these nano-grains, the end appears on thesurface of the deposit increases with the doping with erbium. They also reveal that the nanograins are spontaneously organized in a certain order.The transmission spectra of thin films of titanium oxide doped indicate that they aretransparent in the visible and opaque in the UV. The calculation of the refractive index andporosity of thin films of erbium-doped TiO2, from the transmittance spectra, shows afluctuation of the latter depending on the annealing temperature, thickness and grade erbium.While the optical gap increases. Voir les détails

Mots clés : TiO2, Thin films, Er3+, sol-gel, anatase, Brookite, rutile, Er2Ti2O7, Er2TiO5, Er2O3

Optical and Photo-electrochemical characterization of manganese dioxide/polypyrrole nanocomposite

Assia Tounsi, Chrif Dehchar, Samiha LAIDOUDI, Ouafia BELGHERBI, Belkacem Nessark, Farid Habelhames  (2019)
Article de conférence

PPy-coated manganese dioxide (PPy-MnO2) synthesized by depositing PPy on the surface of γ-MnO2 particles in acetonitrile solution containing 10-1M lithium perchlorate (LiClO4) containing a monomer (pyrrole) and semiconductor (MnO2) nanoparticles. The composite materials (MnO2-PPy/ITO) were characterized by different methods including cyclic voltammetry, impedance spectroscopy, chronoamperometry, scanning electron microscopy (SEM). The cyclic voltammogram showed one redox couple characteristic of the oxidation and reduction composite material of composite material. The impedance spectroscopy study showed that the resistance of the film increases with the MnO2 incorporated in the polymer. The morphological analysis of the film surfaces showed that the MnO2 nanoparticle increased the roughness. These results give information on the use possibility of these materials for energy storage and as photovoltaic cells applications. Voir les détails

Mots clés : Manganese dioxide, Polypyrrole, electrodeposition, optical proprieties.

OPTICAL, STRUCTURAL AND MORPHOLOGICAL CHARACTERIZATION OF ELECTRODEPOSITED CUPROUS OXIDE THIN FILMS: EFFECT OF DEPOSITION TIME

Samiha LAIDOUDI, Mohamed Redha Khelladi, Charif DEHCHAR, Samah BOUDOUR, Leila LAMIRI, Ouafia BELGHERBI, Rabah Boufnik  (2019)
Article de conférence

The purpose of this work is the development and characterization of a novel electrode material based on copper oxide (Cu2O) for use as electrode in catalytic application. The samples are prepared on an indium doped tin oxide (ITO) glass substrate using a simple electrochemical deposition process from a solution of copper (II) sulfate and citric acid. The Cu2O films are deposited under chronoamperometric control at a potential of −0.50V versus SCE at different deposition times ranging from 2 to 15 minutes. The solution was maintained at a temperature of 60°C and a pH of 11. The effect of the deposition time is mainly examined in terms of the change in structural, morphological and optical properties of the Cu2O films using various characterization techniques. Atomic force microscopy (AFM) images showed that the prepared thin films are homogeneous with a granular shape. Also, the surface of the deposits becomes roughened with increasing deposition time. Scanning electron microscopy (SEM) images showed that the morphology of the prepared thin films is composed of a mixture of cubic and pyramidal shapes regularly distributed over the surface of the substrate. X-ray diffraction (XRD) measurements demonstrated that Cu2O thin films prepared by electrochemical deposition have a pure cubic structure with higher preferred growth orientation (111) and good crystallinity. Characterization by UV-Visible spectroscopy showed that the samples have high absorption in the visible region. The calculated values of the direct band gap are between 1.9 and 2.15 eV. These results represent a good starting point for the development of low cost anode used in catalytic application. Voir les détails

Mots clés : Cu2O thin film, electrodeposition, deposition time, optical properties

Theoreticalmodelling for calculation of the energydensities of adsorption sites using inverse gaschromatography

A.BOUHANK, L.BENCHEIKH  (2019)
Publication

The inverse gas chromatography is used to determine the energy densities of theadsorption sites of the stationary solid phase. The use of this technique is old anddates back to the 1940s. The many possibilities offered by this method are describedin several works. This work is an attempt to explore some adsorption local isothermmodels in order to determine the energy density of the adsorption sites. It involves theuse of integral equations of the first kind which are known to be numerically instable.These integral equations were solved by two different methods of solution. One isbased on the use of Taylor series expansions and the other uses the Stieltjes transform.Some interesting theoretical and numerical results are presented. Voir les détails

Mots clés : adsorption, Integral equations, Adsorption isotherms, energy

Etude de quelques modèles pour le calcul des densités énergétiques des sites d'adsorption en utilisant la chromatographie gazeuse inverse

BOUHANK Antar (En préparation)
Thèse de doctorat

Résume :L'application de la Chromatographie Gazeuse Inverse (CGI) pour la détermination des grandeurs physico-chimiques qui caractérisent l'interaction entre une molécule sonde et unsupport chromatographique est déjà ancienne puisque les premiers travaux remontent aux années quarante. Les nombreuses possibilités offertes par cette méthode sont décrites dans plusieurs ouvrages. On se propose dans ce travail d'explorer quelques modèles d'adsorption locales,à savoir l’isotherme d’adsorption de Langmuir générale et de Sips pour calculer la densité énergétique des sites d'adsorption.Pour ce faire on s'appuie surdes méthodes analytiques et numériques. Une des méthodes analytiques utilise la notion de transformée de Stieltjes, alors que la méthode numérique est basée sur la discrétisation de l’équation intégrale en un système d’équations algébriques.  Voir les détails

Mots clés : adsorption, isotherme d'adsorption, Energie, équation d'intégrale