Objective: Since solar energy allows decentralized production of electricity, it can help solve the problem of electrifying isolated sites where a large number of individuals do not have access to energy. This work aims to size a multi-source system for optimal management of the energy produced.
Method: We used an energy management strategy that is an algorithm, which determines at each moment the sharing of power between the different components of the system.
Findings: The sizing tools allowed us to establish relationships between the powers of the components by simple rules, to define the solar power and the storage volume necessary to meet the demand of a load on a given site.
Novelty: This study allowed us to set up an electrical architecture and a control strategy capable of limiting conversion losses and optimizing energy management within the system.
The aim of this study is to produce biogas with household peelings. The peels used are cassava (PM), yam (PI) and plantain (PB) peels. The bibliographic study allowed us to know that this waste has a high yield of biogas. However, the production of biogas with these peelings has acidification problems linked to their acid pH and a high C/N ratio. The use of a digestate from the anaerobic digestion of cow dung as inoculum (I) and a neutralizer such as human urine and cassava effluent allowed the pH to be adjusted around neutrality, which which made it possible to produce flammable biogas with its various peelings.
The main objective of this study is to estimate the drying parameters of cassava using an indirect solar dryer equipped with a sensible heat energy storage system. This dryer, which uses stones as storage material and made of wood and plywood, was used to dry a quantity of 12.2 kg of cassava. Drying parameters relating to drying curves and drying efficiency of cassava were established and studied. The drying curves were modeled using semi-empirical models. The results showed that the water content of cassava decreased from 159.12 g H2O / 100 g dry matter to 13.32 g H2O / 100 g dry matter. With a collector and drying efficiency of 56.64% and 29.39% respectively. The Weibull distribution model allows a satisfactory modeling of the drying curve, with an r2 = 0.988, a χ2 = 0.000896, and an RMSE = 0.0288.
Objectives: The objective of this work is to study the thermal behavior of polypropylene (PP) as phase change material (PCM) with the aim of its use to store energy necessary for cooking in the event of energy deficit for the solar cooker.
Method: We used the differential scanning calorimetry (DSC) method for different speeds, both heating and cooling. We have identified the phase change temperatures of the different samples as well as the evolution of the crystallinity rate of each sample.
Findings: The first heating measurement of the sample is carried out to remove its thermal history. The additional heating measurements gave us information on the behavior of the material (Peak of melting: 167.24°C; Heat of fusion: 86.50 J/g). The cooling measurements gave us access to information such as the differentiation of materials with different histories. The crystallization peak of the recycled material is wider and lower than that of the new material. The temperature peaks of all the curves are around 120°C.
Novelty: The use of the MCP allows us to make a solar cooker autonomous, because the energy stored at the level of the MCP, can ensure the cooking of food during the day in the absence of sunlight and also during the night.
This study shows a simulation with the HOMER software of a hybrid system composed exclusively of renewable energy sources including a solar photovoltaic generator of 50 kW, a 50 kW wind generator and a 50 kW biogas generator linked to a 50 kW converter in Blekoum (rural area of the Abengourou region) fed to date by a 42 kVA diesel generator with a 5000 liters tank. After having modelled the load to satisfy and integrated the wind potential, the sunshine and the biomass residue potential, we carried out the calculation with HOMER. From the three scenarios of hybrid systems after optimization by HOMER, it is appear that, with regard to energy production, the hybrid system produces an average value of 277.364 kWh/year while the 42 kVA generator produces 105.108 kWh/year. The average price per kWh per year one is 481 172.453 FCFA for the hybrid system and 401 491.799 FCFA for the diesel generator. The emissions of gaseous pollutants are very high with the diesel generator where the values of CO2 are raised to 142.933kg/year; CO at 353 kg/year and SO2 at 287 kg/year while the hybrid system allows to preserve our climate by lowering these values respectively CO2 to 33.533 kg/year; CO to 1.261 kg/year and SO2 to 0 kg/year.
This prospective study aimed to mitigate the emission of hydrocarbon gases and economic or energy losses. It consisted in designing a storage system for this volatile fluid, based on local materials, capable of ensuring thermal comfort, under natural conditions of terrestrial heating. In view of their respective theoretical availability, accessibility and thermal conductivity, cotton, sand and shea cake have been identified as potential insulators. For this purpose, identical samples of the fuel were buried, each with a specific material. They were respectively subjected to a fraction of solar energy, transmitted according to the thermal properties of the material crossed. The monitoring of the evolution of the different evaporation rates per sample made it possible to classify the insulation tested in order of performance in non-evaporation rate: 1st) shea cake with 90.81%; 2nd) cotton, 89.29%; 3rd) sand, 85.05% and 4th) air, 80.68%. In the light of a multi-criteria analysis by Thomas Saaty, based on more restrictive ecological and economic constraints, shea cake and sand were preferentially chosen. They made it possible to build a fuel storage matrix, called “Eco1-stoc”, which recorded an experimental non-evaporation rate of 91.53%. Therefore, the Eco1-stoc can be one of the solutions to be advised in operating conditions similar to those of Korhogo.
In Africa, it is possible to take advantage of the heat provided by metal roofs (constantly exposed to the sun) for the drying of agricultural products to reduce post-harvest losses. For this purpose, a prototype ventilated attic equipped with shelves is built and tested on the drying of cassava. For 6 kg of manioc, it takes three days to dry in the prototype. The modeling of moisture growth in the drying air is carried out by the fourth-order Runge-Kutta method. The theoretical results allow predicting the variation of moisture in the air of the attic with accuracy. Modeling of the manioc drying curve is made using five semi-empirical models. The Midili-Kucuk model is the one that best predicts moisture content evolution in cassava, as it gives the highest value of the determination coefficient. As drying is a simultaneous heat and mass transfer phenomenon, the coefficients of heat and mass transfer evolutions were observed too. We noticed their increase with drying time. The presence of fresh products in the attic keeps its internal temperature lower than outside. When the products are no longer fresh, the temperature of the attic (on the products) increases. Polystyrene insulation on the ceiling, product bed and air circulation generated by chimneys help prevent heat from migrating through the ceiling. So, this attic has two advantages: the drying of products to extend its shelf life and reduction of heat in houses.
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