• Energy Research
• 2025-2025close
• SN close

Solar thermal energy is available in abundance in a country like Senegal where direct solar radiation is on average 1950kWh/m2 per year. Solar drying is the most popular method to preserve food in our country. However, it is limited by the intermittent nature of the sun. The objective of this paper is to overcome the intermittency of the sun by integrating a thermal bed into the solar dryer. The thermal bed is made of basalt and biochar for heat storage and humidity absorption respectively. An experimental study was done using papaya and moringa leaves. The results obtained show that the thermal bed stores heat at the temperature of 39°C at 10p.m. Papaya is dried in two days and moringa leaves are dried in one day. For papaya slices, water content is 15% and was reached at the second day of drying. Also, moringa dry leaves water content is 8%. This value begins to be reached from 3 p.m. in the afternoon. Thus, the thermal bed temperature, the air temperature between the drying racks and the drying chamber outlet air temperature are respectively an average of 48.67°C, 48°C and 47.22°C compared to 34.33°C of the ambient temperature, a difference of more than 4°C. The experimental study is supported by a Computational fluid dynamic (CFD) analysis.

AbstractClimate change significantly challenges smallholder mixed crop-livestock (MCL) systems in sub-Saharan Africa (SSA), affecting food and feed production. This study enhances the SIMPLACE modeling framework by incorporating crop-vegetation-livestock models, which contribute to the development of sustainable agricultural practices in response to climate change. Applying such a framework in a domain in West Africa (786,500 km2) allowed us to estimate the changes in crop (Maize, Millet, and Sorghum) yield, grass biomass, livestock numbers, and greenhouse gas emission in response to future climate scenarios. We demonstrate that this framework accurately estimated the key components of the domain for the past (1981–2005) and enables us to project their future changes using dynamically downscaled Global Circulation Model (GCM) projections (2020–2050). The results demonstrate that in the future, the northern part of the study area will likely experience a significant decline in crop biomass (up to -56%) and grass biomass (up to -57%) production leading to a decrease in livestock numbers (up to -43%). Consequently, this will impact total emissions (up to -47% CH4) and decrease of -41% in milk production, and − 47% in meat production concentrated in the Sahelian zone. Whereas, in pockets of the Sudanian zone, an increase in livestock population and CH4 emission of about + 24% has been estimated, indicating that variability in climate change impact is amplifying with no consistent pattern evident across the study domain.

In the current economic, energy and environmental context, the implementation of technologies using renewable energies as a source of power electricity and cooling production is very beneficial insofar as it allows the reduction of pollution and the cost of fossil fuels. Senegal has a sunshine potential well distributed across the country for irradiation varying from South to North between 1850 KWh/m²/year and 2250 kWh/m²/year. It is one of the best solar potentials in the world. Systems operating on the organic Rankine cycle ORC and the absorption cooling system ACS are innovative and sustainable technologies for the exploitation of low enthalpy renewable energy sources. In this present work, the thermodynamic analysis of a combined ORC and ACS system for power electricity and cold production is carried out numerically using the Engineering Equation Solver (EES) software. R245fa and water-lithium bromide mixture are used as working fluid for ORC and ACS respectively. The results obtained at the ACS subsystem level show that the COP of ACS decreases when the absorption temperature increases. This reduction goes from 0.83 to 0.55, i.e. a reduction of 0.28 for a variation of absorption temperature from 27°C to 45°C. The COP has stabilized for generator temperatures above 95°C and is in the range of 0.7 to 0.8. These fluctuations are due to the irreversibility at the level of the components of the system. For the ORC subsystem, the turbine power and ORC condenser power decrease as the ORC condensing pressure increases. Thus, the turbine power goes from 235 kW to 200 kW and the ORC condenser power goes from 80 kW to 60 kW.