Sciences de la matièreSciences de la matièrehttp://dspace.univ-batna.dz/xmlui/handle/123456789/202024-03-29T05:16:15Z2024-03-29T05:16:15ZSimulation et optimisation des cellules solaires des structures Metalisolant-semiconducteur MIS a differents materiaux semiconducteurs en couche minceBenmachiche, samirahttp://dspace.univ-batna.dz/xmlui/handle/123456789/74212024-01-14T14:02:15Z2023-01-01T00:00:00ZSimulation et optimisation des cellules solaires des structures Metalisolant-semiconducteur MIS a differents materiaux semiconducteurs en couche mince
Benmachiche, samira
At present, silicon-based solar cells hold a dominant position in the solar cell market due to silicon's appropriate band gap matching the solar spectrum and its abundance on Earth. However, the efficiency of silicon-based solar cells has limitations, leading researchers and developers to focus on alternative approaches for further advancements in solar cell technology.
Advancements in technology pave the way for cutting-edge research in the development of highly efficient and cost-effective MIS solar cells, offering promising prospects for diverse and widespread applications. The device was subjected to precise analyses using the Silvaco Atlas software, enabling a comprehensive numerical investigation into the correlation between various effects and the device's performance and reliability.
In this thesis, the electrical performance of a metal-insulator-semiconductor (MIS) solar cell is evaluated. The focus is on its design with various high-k dielectrics, the objective of the study is to optimize the device's geometrical dimensions while enhancing quantum mechanical tunneling mechanisms, The thesis also provides a comprehensive comparison between the suggested solar cell structures using crystalline silicon (c-Si) and thin film silicon (hydrogenated amorphous silicon, a-Si:H).It explains the physics underlying both thin-film silicon solar cells and c-Si, emphasizing the use of diverse material selections involving high-k insulator layers. These layers play a pivotal role in overcoming the limitations of conventional SiO2, such as Al2O3, HfO2, Si3N4, TiO2, and Ta2O5. The evaluation focuses on comparing performance parameters, with a primary emphasis on conversion efficiency. Additionally, the study assesses the impact of interface state density, doping density, oxide thickness, and oxide fixed charge on the electrical outputs of the proposed MIS solar cell.
As observed from the responses of the devices, MIS diodes utilizing HfO2 and Ta2O5 as the insulating layers exhibit the highest efficiency under visible light. This is attributed to the fact that these diodes enable more efficient tunneling of hot electrons due to the asymmetry of the thin energy barrier. Consequently, the insulating layer plays a crucial role in determining the tunneling probability of electrons and optimizing the conversion efficiency, as evidenced by the findings of this study.
2023-01-01T00:00:00ZEVALUATION OF AEROSOLS’ EFFECT ON THE EFFICIENCY OF SOLAR TOWER POWER PLANTS IN ALGERIAZereg, Kacemhttp://dspace.univ-batna.dz/xmlui/handle/123456789/74202024-01-14T13:46:19Z2023-01-01T00:00:00ZEVALUATION OF AEROSOLS’ EFFECT ON THE EFFICIENCY OF SOLAR TOWER POWER PLANTS IN ALGERIA
Zereg, Kacem
The environmental concerns about greenhouse gases and the consequent climate change urge the transition towards cleaner, renewable energy sources. Solar energy applications are promising to play an important role in energy transition, especially photovoltaics (PV) and concentrated solar power (CSP) technologies. CSP plants are of interest, particularly solar tower plants, thanks to the possibility of reaching high temperatures, and thus more important efficiencies. The Algerian Sahara has a high potential to host solar projects in general and CSP ones in particular thanks to its high annual levels of incident, direct solar irradiance, and there already are pilot projects to assess this potential, however, the environmental hostility of the Sahara requires the prior evaluation of the possible optical losses suffered by solar mirrors due to the presence of high aerosols’ loads and dust particles. Such particles would attenuate considerably the incident solar energy, either by atmospheric extinction due to suspended particles, or due to the deposition of these soiling particles on the surfaces of solar mirrors.
In the present thesis, we make a first step towards the evaluation of reflectivity losses of solar tower’s heliostats under Saharan climate (since this issue has never been studied in Algeria), and this through the first outdoor heliostats’ soiling campaign at a CSP-suitable site in the province of Laghouat, we also explore soiling mitigation approaches that are water-economic such as coatings. To do so, we used an experimental setup to expose several solar mirrors to outdoor arid climate conditions of Laghouat city. The trends of the measured reflectivity are consistent with the theoretical and bibliographic background. Also, the physical and chemical properties of dust particles -deposited on the mirrors- are investigated through the characterization by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-rays diffraction (XRD), the desired properties were investigated in the Technical Platform for Physical and Chemical Analysis (CRAPC-PTAPC) located in Laghouat as well, next to where the experimental setup was installed. Another important contribution of the present thesis is publishing the first paper to review the literature of dust-related problems for CSP, unlike photovoltaic technology which benefited from multiple reviews. In our future work, we plan to geographically extend the present study for the purpose of assessing the potential of different Algerian regions to host concentrated solar power plants in general, and solar tower projects in particular.
2023-01-01T00:00:00ZEVALUATION OF AEROSOLS’ EFFECT ON THE EFFICIENCY OF SOLAR TOWER POWER PLANTS IN ALGERIAZereg, Kacemhttp://dspace.univ-batna.dz/xmlui/handle/123456789/74192024-01-14T13:41:06Z2023-01-01T00:00:00ZEVALUATION OF AEROSOLS’ EFFECT ON THE EFFICIENCY OF SOLAR TOWER POWER PLANTS IN ALGERIA
Zereg, Kacem
The environmental concerns about greenhouse gases and the consequent climate change urge the transition towards cleaner, renewable energy sources. Solar energy applications are promising to play an important role in energy transition, especially photovoltaics (PV) and concentrated solar power (CSP) technologies. CSP plants are of interest, particularly solar tower plants, thanks to the possibility of reaching high temperatures, and thus more important efficiencies. The Algerian Sahara has a high potential to host solar projects in general and CSP ones in particular thanks to its high annual levels of incident, direct solar irradiance, and there already are pilot projects to assess this potential, however, the environmental hostility of the Sahara requires the prior evaluation of the possible optical losses suffered by solar mirrors due to the presence of high aerosols’ loads and dust particles. Such particles would attenuate considerably the incident solar energy, either by atmospheric extinction due to suspended particles, or due to the deposition of these soiling particles on the surfaces of solar mirrors.
In the present thesis, we make a first step towards the evaluation of reflectivity losses of solar tower’s heliostats under Saharan climate (since this issue has never been studied in Algeria), and this through the first outdoor heliostats’ soiling campaign at a CSP-suitable site in the province of Laghouat, we also explore soiling mitigation approaches that are water-economic such as coatings. To do so, we used an experimental setup to expose several solar mirrors to outdoor arid climate conditions of Laghouat city. The trends of the measured reflectivity are consistent with the theoretical and bibliographic background. Also, the physical and chemical properties of dust particles -deposited on the mirrors- are investigated through the characterization by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-rays diffraction (XRD), the desired properties were investigated in the Technical Platform for Physical and Chemical Analysis (CRAPC-PTAPC) located in Laghouat as well, next to where the experimental setup was installed. Another important contribution of the present thesis is publishing the first paper to review the literature of dust-related problems for CSP, unlike photovoltaic technology which benefited from multiple reviews. In our future work, we plan to geographically extend the present study for the purpose of assessing the potential of different Algerian regions to host concentrated solar power plants in general, and solar tower projects in particular.
2023-01-01T00:00:00ZLe biogaz comme combustible d’un moteur à combustion interneRahmouni, Ibrahimhttp://dspace.univ-batna.dz/xmlui/handle/123456789/74082024-01-14T10:44:27Z2023-01-01T00:00:00ZLe biogaz comme combustible d’un moteur à combustion interne
Rahmouni, Ibrahim
Le but principal de cette thèse est d'évaluer les performances d'un moteur à combustion interne alimenté au biogaz brut. A cet effet, une étude expérimentale a été menée sur un moteur à essence de type Honda GX140, monocylindre de 5 CV couplé à un dynamomètre hydraulique TD115, fonctionnant avec du biogaz brut et de l'essence. Le biogaz brut a été produit à partir d'une installation laboratoire de biogaz au laboratoire LPEA, de l'Université Batna 1. Les résultats indiquent que la qualité du biogaz produit avec le substrat unique (mono-digestion) de la bouse de vache est meilleure que celle du biogaz produit par la codigestion du la bouse de vache et des déchets ménages. D'autre part, les performances du moteur ont été analysées au laboratoire Moteur de l'Université Batna 2 ; sous deux conditions de charge du moteur ; 0 et 3,5 N.m, les performances du moteur ont été étudiées. Une augmentation significative de la température d'échappement et du le débit massique de carburant ont été observées dans le cas du biogaz brut. Les résultats ont également révélé que le biogaz brut générait une efficacité thermique des freins et une consommation de carburant spécifique aux freins plus élevées que l'essence. Cela ouvrira la porte au biogaz pour substituer partiellement aux combustibles d'origine fossile et avec tous les effets sociétaux positifs que générerait cette substitution.
Mots clés
2023-01-01T00:00:00Z