Publications Internationales
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Item A comprehensive numerical study on melting performance in a storage cavity with partial metal foam integration: Design and economic assessment(Elsevier, 2024) Cheradi, Hanane; Haddad, Zoubida; Iachachene, Farida; Mansouri, Kacem; Arıcı, MüslümDespite remarkable technological progress aimed at improving thermal performance of storage systems, designing cost-effective thermal storage solutions still remains a challenge. Consequently, to address this gap, the current study provides a detailed numerical analysis of the melting performance within a storage cavity with partial metal foam integration, considering both design and economic aspects. Five distinct designs were considered to provide a comprehensive assessment of the melting process including non-porous and porous designs. Various factors such as foam position, foam shape and foam filling ratio were examined under different criteria. The results revealed that designs employing kite-shaped, triangular-shaped, square-shaped, and trapezoidal-shaped foam under optimal location resulted in melting time reduction of 74.8 %, 67.0 %, 50.9 %, and 42.8 %, respectively, in comparison to the non-porous design. The findings highlight the kit-shaped foam as the optimal foam shape, with a notable 7.8 % difference in melting times between designs with kite and triangular foams, and an 8.1 % disparity between designs with square and trapezoidal foams. From an economic assessment, it was found that the kit-shaped foam filling design, with a 1/3 filling ratio, proved to be cost-effective when the unit price ratio of the metal foam to PCM fell within the range of 4 to 12. Interestingly, for ratios below 4, the same design, with a 1/2 filling ratio, emerged as an economical solution. This study contributes to the field by providing quantitative insights into the design and economic viability of metal foam integrated thermal storage systems.Item Effect of Temperature on the Performance of CGS/CIGS Tandem Solar Cell(Sumy State University, 2023) Elbar, Mourad; Tobbeche, Souad; Chala, Slimane; Saidani, Okba; Kateb, Mohamed Nadjib; Redha Serdouk, MohamedThe CGS and CIGS being promising materials for large scale photovoltaic applications, the effect of temperature on the electrical parameters of a CGS/CIGS tandem solar cell has been investigated in this work. The copper gallium diselenide (CGS) and copper indium gallium diselenide (CIGS) structures as topcell and bottom-cell respectively, were numerically simulated under AM1.5G spectral illumination using the two-dimensional device simulator Silvaco-Atlas. The temperature dependency of the solar cell’s characteristics was investigated in the temperature range from 300 to 400 K at intervals of 20 K. The simulation results show the density current (Jsc) slightly increases whereas the open-circuit voltage (Voc) and fill factor (FF), conversion efficiency (ƞ) decreases with the increase in temperature. The tandem cell operating temperature efficiency was found to be (– 0.34 %/K), which is slightly higher than that of CGS solar cell (– 0.29 %/K), but markedly better than that of CIGS solar cell (– 0.41 %/K).Item Numerical and experimental investigation of hydraulic fracture using the synthesized PMMA(Springer, 2021) Khadraoui, Sofiane; Hachemi, Messaoud; Allal, Ahmed; Rabiei, Minou; Arabi, Abderraouf; Khodja, Mohamed; Lebouachera, Seif El Islam; Drouiche, NadjibHydraulic fracturing is a technique used for stimulation of unconventional reservoirs including shale plays. Several parameters, including rock properties, state of stresses, and fracturing fluid characteristics, influence successful design and implementation of a hydraulic fracturing operation. Monitoring of real-time hydraulic fracture initiation and propagation in the field to improve the design parameters is costly. Several hydraulic fracturing laboratory studies have been reported; however, similar to the field operations, real-time observation of the fracturing fluid penetration to the rock sample is not practical throughout the test but the sample can only be inspected post-experiment. In this work, we present the specifications of a through see synthesized polymethyl methacrylate (PMMA) material which was made for the purpose of laboratory experimental hydraulic fracturing testing. The mechanical testing of the PMMA allowed us to obtain the mechanical properties, including tensile and compressive strengths as well as toughness are close to the typical tight samples used in the laboratory for hydraulic fracturing experiments. Hydraulic fracturing tests were performed on a number of cylindrical PMMA samples to investigate the effect of injecting fluid viscosity and flow rate as well as the geometry of the initial crack on fracture breakdown pressure and the characteristics of the propagating fracture. The ability to directly observe the fracture geometry throughout the experiment allowed us to make a good correspondence between the pressure–time curve and the evolution of the fracture geometry. Numerical modeling using ANSYS was performed to run multiple simulations and do sensitivity analysis of different parameters similar to the laboratory experiments. The results also were compared with some of the analytical solutionsItem Effect of Thermal Collector Height and Radius on Hydrodynamic Flow Control in Small Solar Chimney(Penerbit Akademia Baru, 2020) Daimallah, Ahmed; Lebbi, Mohamed; Lounici, Mohand Said; Boutina, LyesSolar chimney power plant (SCPP) is one of the promising technologies for solar energy utilization. It is an interesting system especially in large isolated desert areas due to its basic techniques and low operating costs. In this study, we investigate numerically the collector geometrical parameters effect on the hydrodynamic flow control in a solar chimney. The finite volume method and the SIMPLE algorithm have been used to solve the turbulent flow equations and energy equation. A standard K-ε model is used. The influence of the collector height (0.05m≤Hc≤0.5m) and the collector radius (2.5m≤Rc≤15m) on the flow behavior has been numerically analyzed. The obtained results indicate that increasing the collector height and collector radius affect considerablythe flow behavior and the SCPP performance. The mass flow rate is enhanced by about 27 %, for Rc=12.5m and Hc = 0.25m.Item Rayleigh number effect on the turbulent heat transfer within a parallelepiped cavity(2011) Aksouh, Mohamed; Mataoui, Amina; Seghouani, Nassim; Haddad, ZoubidaThis purpose is about a 3-D study of natural convection within cavities. This problem is receiving more and more research interest due to its practical applications in the engineering and the astrophysical research. The turbulent natural convection of air in an enclosed tall cavity with high aspect ratio (Ar = = H/W = 28.6)is examined numerically. Two cases of differential temperature have been considered between the lateral cavity plates corresponding, respectively, to the low and high Rayleigh numbers: Ra = 8.6.10 5 and Ra = = 1.43.10 6. For these two cases, the flow is characterized by a turbulent low Reynolds number. This led us to improve the flow characteristics using two one point closure low-Reynolds number turbulence models: renormalization group κ-ε model and shear stress transport κ-ω model, derived from standard κ-ε model and standard κ-ω model, respectively. Both turbulence models have provided an excellent agreement with the experimental data. In order to choose the best model, the average Nusselt number is compared to the experiment and other numerical results. The vorticity components surfaces confirm that the flow canbe considered 2-D with stretched vortex in the cavity core. Finally, a correlation between Nusselt number and Rayleigh number is obtained to predict the heat transfer characteristicsItem Vortex breakdown control in confined swirling flows(2008) Saci, Rachid; Kouadri, AmarConfined steady flows, which display on-axis or off-axis vortex breakdown, have been numerically studied, with particular attention focused on means of controlling the vortex breakdown bubbles. Firstly, the model flow driven by one end disk of a cylindrical enclosure, which exhibits two distinct on-axis vortex bubbles, has been considered. The resulting computations revealed that, sloping slightly the stationary sidewall, beyond a threshold angle, provided an effective means of removing the secondary vortex structure, and the flow remains steady. Besides, this technique is shown to significantly modify the flow topology which displays off-axis bubbles, induced by the co-rotation of the end disks. Then, the effectiveness of adding a near-axis swirl, as suggested in recent experimental works, has been analysed numerically and found to substantially alter on-axis reverse flowsItem Numerical simulation of transient vaporous and gaseous cavitation in pipelines(2001) Kessal, M.; Amaouche, MustaphaThe transient vaporous and gaseous cavitation phenomena in an elastic pipeline are investigated for homogeneous liquid-gas mixture flow. It has been shown, in the case of two components having the same velocity, that modelling is also possible by considering the continuous character of the medium, i.e. without any location of column separation. The governing equations have been solved by using two finite difference schemes: the Mac Cormack’s scheme and an improved new finite difference two-time step scheme. Characteristics method is used at the boundaries. The theoretical results obtained are compared and found to correlate well with similar resultsItem An investigation of highly pressurized transient fluid flow in pipelines(2012) Ouchiha, Z.; Loraud, J. C.; Ghezal, A.; Kessal, M.; Benzaoui, A.; Ghiaasiaan, M.This paper discusses transient processes in natural gas pipelines. The method of characteristics (MOC) is applied for the analysis of two transient categories, where the governing one-dimensional, hyperbolic conservation equations are linearized and solved without neglecting any of their term. First, we present a parametric study of the pressurized flow encountered when pipelines are utilized for the transportation or the temporary storage of natural gas. The non-ideal compressibility of natural gas is included in the model and its impact on the thermo-hydraulic processes is elucidated. Second, we model the hydrodynamics of a pipeline whose downstream boundary is a periodic discharge rate. The results show that, in response to these boundary conditions, the pressure distribution in the pipeline also undergoes periodic variations. Furthermore, our simulation results confirm the usefulness of MOC for numerical simulation of flow phenomena in pipelines