This work is part of the dynamic of proposing a solution to the problem of access to electricity in Chad, which has a rate of access to electricity of 3%. N’Djamena has significant solar potential that can be harnessed to generate electricity. In this paper, we present a theoretical study of the performances of the Dish/Stirling system with the purpose of producing electricity, based on a mathematical model taking into account each of the subparts of the system (concentrator, solar cavity receiver, and Stirling engine). Hydrogen is preferred to helium as the working fluid for operating the Stirling engine at high temperatures. This coupled model made it possible to estimate the monthly average of the electric power produced by this modular system and also its overall solar electricity yield.
This study presents an experimental investigation and thermodynamic 0D modeling of the combustion of a compression-ignition engine, fueled by an alternative fuel based on neem biodiesel (B100) as well as conventional diesel (D100). The study highlights the effects of the engine load at 50%, 75% and 100% and the influence of the heat loss models proposed by Woschni, Eichelberg and Hohenberg on the variation in the cylinder pressure. The study shows that the heat loss through the cylinder wall is more pronounced during diffusion combustion regardless of the nature of the fuels tested and the load range required. The cylinder pressures when using B100 estimated at 89 bars are relatively higher than when using D100, about 3.3% greater under the same experimental conditions. It is also observed that the problem of the high pressure associated with the use of biodiesels in engines can be solved by optimizing the ignition delay. The net heat release rate remains roughly the same when using D100 and B100 at 100% load. At low loads, the D100 heat release rate is higher than B100. The investigation shows how wall heat losses are more pronounced in the diffusion combustion phase, relative to the premix phase, by presenting variations in the curves.
The objectives of this work carried out in the Central African Republic are to propose new correlations between the components of solar radiation and the sunshine duration on a horizontal surface on the ground, and then to make an evaluation of the solar potential in the cities of Bambari, Birao and Bangui. Polynomial regression models were used and their parameters were estimated by the ordinary least squares method. A statistical evaluation allowed us to compare the performance of the models. The best correlations are then used to estimate the global and diffuse radiation. In the city of Birao, the estimated global radiation is around 6 kWh/m2.j and the diffuse radiation around 2 kWh/m2.j ; in Bambari the global radiation is around 5.4 kWh/m2.j and the diffuse around 2.3 kWh/m2.j ; in Bangui the global radiation is around 5 kWh/m2.j and the diffuse radiation around 2.3 kWh/m2.j. The potential solar in all these regions is very favorable for small and large-scale solar photovoltaic applications.
This manuscript deals with a quasi-steady regime thermal analysis of a solar parabolic trough collector in the climatic conditions of the city of N'Djamena located in a Sahelian region of the Chad Republic. The objective is to develop the solar electricity potential of N'Djamena and contribute to the development of renewable energies in the country. A one-dimensional numerical model was developed in a quasi-steady regime to simulate and analyze the thermal behavior of the system. The energy balance equations governing the thermal behavior of the collector are solved by the implicit finite difference method, while considering the variation of the solar radiation over time. Initially, the model was validated by experimental data existing in the literature. Excellent agreement is observed when comparing the numerical results to experimental data. The effect of various parameters, including the type of heat transfer fluids, wind speed, and mass flow rate of fluid, on the thermal performance of the parabolic trough solar collector in quasi-steady regime operation was observed. It is shown that the variation of wind speed has a very slight effect on the thermal performance of the collector. Four fluids (therminol 66, therminolV-P1, untreated water, and treated water) were simulated between 11:00 and 15:00 local time. Through the simulation of four fluids, it was shown that the energy efficiency of the collector when using oil is much better than with water.
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