Publications Internationales

Permanent URI for this collectionhttps://dspace.univ-boumerdes.dz/handle/123456789/13

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Subject: search.filters.subject.Nanoparticles

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    Numerical investigation and optimization of melting performance for thermal energy storage system partially filled with metal foam layer: New design configurations
    (Elsevier, 2023) Haddad, Zoubida; Iachachene, Farida; Sheremet, Mikhail A.; ;Abu-Nada, Eiyad
    Low thermal performance of storage systems represents a barrier to their industrial/engineering application and commercialization. Among all the proposed methods, combination of phase change material with metal foams appears more promising due to the high thermal conductivity of metal foams. However, the insertion of metal foams reduces the PCM volume; hence, a lower amount of stored energy. The present numerical study thoroughly addresses this issue with a focus on the optimization of melting performance for thermal energy storage system partially filled with metal foam layer. A finite volume method based on the enthalpy–porosity technique has been adopted for the numerical simulations. The metal foam location, porosity, and nanoparticle volume fraction were optimized to explore their effects on the melting performance. The results showed that inserting the foam layer diagonally from the top left to the right bottom leads to the lowest melting time. Compared to pure PCM, the melting time increases by 77.7%, while the stored energy decreases by 6.7%. The optimum porosity was found to be 0.88 as it gives approximately the same amount of stored energy as that of pure PCM with a deviation of 4%. Adding nanoparticles to pure PCM increases the melting rate by approximately 8%, while it decreases the stored energy by almost 3%. It is concluded that hybrid systems, i.e., metal foam at an optimum porosity and nanoparticles is more efficient than using each technique separately
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    Studies on equilibrium swelling, dye adsorption, and dynamic shear rheology of polymer systems based on chitosan-poly(vinyl alcohol) and montmorillonite
    (Taylor & Francis, 2019) Amri, Nedjla; Radji, Sadia; Ghemati, Djamila; Aliouche, Djamel
    Chitosan-poly(vinyl alcohol)/clay membranes were prepared by physical blending. Thesehybrid systems were characterized through infrared spectroscopy, microscopy, swelling, andoscillatory rheology. Adsorption of a commercial reactive dye by these membranes was fur-ther studied. Results showed that more stable blend membranes were formed due to thestrong interaction in the polymers. These membranes showed substantial percent swellingin water and shrinking in saline solution. Adsorption analysis showed the ability of theblends to fix organic dyes, and to be used in liquid waste processing. In dynamic rheology,it was observed that all measured viscoelastic properties were influenced by polymer com-position and clay content. For all samples, results show a typical behavior of an entangledsystem in the case of low concentrated macromolecular viscoelastic fluids. The dynamicmoduli exhibited higher values for blends, compared with values of the pure polymers,which is an indication of good stability and tendency of gel formation
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    Synthesis and characterization of Er3+/Cu+-codoped fluorophosphate glasses
    (Elsevier, 2019) Abdedou, N.; Djouama, T.; Chalal, M.; Poulain, M.; Capoen, B.; Mahiou, R.
    NaPO3-ZnF2 binary fluorophosphate glasses doped with trivalent erbium and monovalent copper were synthesized by the conventional melting and casting method using ErF3 and CuCl as starting materials. The samples were systematically investigated using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. X-ray powder diffraction patterns confirmed that the as-prepared compounds were all amorphous. The glass transition temperature (Tg) was observed around 230 °C by DSC analysis, while the thermal stability range (ΔT) was estimated to be between 90 and 140 °C. The measured value of the refractive index (n) was measured as 1.502 at a wavelength of 632.8 nm. Thermal annealing of the samples was performed at different temperatures above Tg for various heat-treatment times. During these steps, monovalent copper and sodium ions were expected to be reduced, forming metallic nanoparticles. This transformation lead to coloration changes, depending on the annealing time and temperature, with respect to the transparency of the glasses. These spectroscopic changes are related to the plasmonic effects induced by the presence of both Cu and Na metallic nanoparticles, which promote red shift due to absorption. The VIS-NIR absorption spectra of the prepared glasses were investigated in the frame work of standard Judd-Ofelt (J-O) theory, which was used to determine the J-O intensity parameters, radiative transition probabilities and branching ratios for Er3+ ions embedded in the glasses. The calculated intensity parameters (Ω2,4,6) were compared to those obtained for Er3+ in several other glasses
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    A review on how the researchers prepare their nanofluids
    (Elsevier, 2014) Haddad, Zoubida; Abid, Chérifa; Oztop, Hakan F.; Mataoui, Amina