Browsing by Author "Kebabsa, Hakim"

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Corrigendum to “Thermo-hydrodynamic behavior of an innovative solar chimney” [Renew. Energy 145 (2020) 2074–2090]
(Elsevier, 2020) Kebabsa, Hakim; Lounici, Mohand Said; Lebbi, Mohamed; Daimallah, Ahmed
Élaboration et caractérisation des couches minces protectrices (Ti-Si) pour application sur les aubes de turbine à gaz
(Université M’Hamed Bougara Boumerdès : Faculté des Hydrocarbures et de la Chimie, 2016) Kebabsa, Hakim; Hamzaoui, Mohamed; Gaceb, Mohamed (Promoteur)
Le but de ce travail est d'étudier, en premier, l'effet de différents paramètres sur les propriétés des couches minces de nitrure de titane, de siliciure de titane et d'établir des relations entre les conditions de dépôt. Le deuxième objectif est d'étudier l'effet de l'incorporation d'azote dans la structure de siliciure de titane pour établir une couche avec une dureté optimale ainsi qu'une résistance à l'usure et à la corrosion sèche élevée pour un bon fonctionnement des aubes de la turbine à gaz.
Investigation of techniques for improving solar chimneys
(2020) Kebabsa, Hakim
Diverse renewable energy systems accessible to technologically less developed countries are urgently needed to ensure energy security, enrich the generation portfolio, and tackle clean development issues. Solar chimney power plants (SCPP) offer this opportunity and have been accepted as one of the promising technologies for solar energy utilization. The present study consists of an investigation of various techniques for the improvement of this system. The sloped collector is an interesting technique to improve SCPP performance. Taking benefit from the sloped collector advantages while limiting its disadvantages, a novel concept, which consists of a horizontal collector with an adapted collector entrance, has been proposed. Optimization of this concept has allowed a considerable gain in the system performance. The passive flow control method, widely used as a key element in engineering, has also been used within the collector. Three different profiles of control devices have been selected to highlight the impact of this control technique on energy transfer. The divergent tower solar chimney is an attractive upgrading of the solar chimney system. However, the boundary layer separation phenomenon can appear when the divergence angle exceeds a specific value, inducing system performance degradation. A novel solar chimney tower concept, named annular tower solar chimney power plant, has been proposed to deal with the boundary layer separation phenomenon and improve the divergent tower system. Accordingly, the influence of tower dimensions has been evaluated. An improved concept that allows a compromise between induced cost and performance gain has also been suggested. The demand for solar energy technologies is increasing due to the growing interest in renewable energies. However, these technologies are affected by atmospheric conditions and low overall efficiency. A combined solar chimney-photovoltaic system has been proposed to deal with chimney system deficiencies. The performance of this sustainable system has been evaluated. The energy produced under the climatic conditions of Algeria has also been estimated
Numerical investigation of a novel tower solar chimney concept
(elsevier, 2020) Kebabsa, Hakim; Lounici, Mohand Said; Daimallah, Ahmed
Divergent tower solar chimney power plant is an attractive upgrading of the solar chimney system. However, boundary layer separation (BLS) phenomenon can appear when the divergence angle exceeds a specific value, inducing system performance degradation. The present paper proposes a novel solar chimney tower concept, named annular tower solar chimney power plant (ATSCPP), to deal with BLS phenomenon and improve the divergent tower system. Accordingly, the influence of exterior tower radius (ETR) and interior tower radius (ITR) were evaluated, using the Spanish prototype. Simulations were carried out using a 3D model. The results indicate that flow behavior, power output and thermal efficiency shows a strong sensitivity to the change of both ETR and ITR. The best case is obtained when (ETR = 17 m, ITR = 13 m). The new solar chimney tower concept allowed a significant increase in the driving potential. The total improvement in power output reaches 32%. An improved concept which allows a compromise between induced cost and performance gain of the system is also proposed.
Performance evaluation of the combined solar chimney-photovoltaic system in Algeria
(Elsevier, 2021) Kebabsa, Hakim; Lounici, Mohand Said
The demand for solar energy technologies is increasing due to the growing interest in renewable energy. However, these technologies are affected by atmospheric conditions and low overall efficiency. The present study proposes a combined solar chimney-photovoltaic (SC-PV) system to deal with stand-alone system weaknesses. This work evaluates this self-sustainable system's performance and estimates the electric energy generated under the climatic conditions of Algeria using computational fluid dynamics (CFD). The model is first validated using the Spanish prototype experimental data. The simulations show that the proposed system provides several valuable benefits for improving turbine power, solar cell temperature, and PV efficiency. The results indicate the SC in the combined system performs better turbine generated power than a stand-alone system only for an appropriate PV location and width. Using the heat released from the PV to increase the kinetic energy of airflow beneath the collector, the total improvement in turbine power reaches 8.91%. Similar to the optimal PV widths (10 m), other widths, varying from 20 m to 30 m, increase the overall turbine power without degrading SC performance. Using the SC-PV as a cooling method, the solar cell temperature decreases by 12.12% (6.30 °C) compared with cell temperature in the stand-alone system (52 °C). Accordingly, the PV efficiency increases by 3.23% compared with PV efficiency in the stand-alone system (13.18%). The results also indicate the highly intensive solar radiation region (Adrar) has higher monthly turbine power than other areas. The appropriate areas for building such a system will be in the south of the country, where the solar potential is high. In these regions, the SC-PV could contribute to satisfying the electricity demand
Thermo-hydrodynamic behavior of an innovative solar chimney
(Elsevier, 2020) Kebabsa, Hakim; Lounici, Mohand Said; Lebbi, Mohamed; Daimallah, Ahmed
Production of electricity through solar systems is a viable alternative, especially for deserted regions where access to electricity is difficult. Solar chimney power plant (SCPP) is one of the promising concepts in renewable energy technology that needs performance enhancement. The objective of this research is to investigate a novel concept, which consists of a horizontal solar chimney power plant with an adapted collector entrance, named sloped collector entrance SCPP (SCESCPP). The effect of the collector entrance shape (slope, sloping distance) is investigated. For each sloping distance, eleven values for the slope are examined. Thus, a numerical investigation is carried out using a 2D axisymmetric chimney model. The model was first validated using experimental results. The influence on air thermo-hydrodynamic behavior of this system is comprehensively studied to enhance the understanding and deepen the analysis in order to improve the performance of the SCPP. The results indicate that the new collector entrance design influences the system performance in a significant manner. It is shown that the best performing configuration (sloping distance of 0.8 and slope of 9.1°) produces an available power reaching 16.36% more than that for zero slope collector roof at same conditions. Moreover, it is found that the optimal slope depends on sloping distance and remains almost the same for different Rayleigh numbers