Comparative Study of Thermal Accumulators for Solar Drying of Fruits and Vegetables: A Case Study at the Higher Institute of Technology of Mamou, Guinea

Abstract

Access to sustainable food preservation methods represents a major challenge for food security in sub-Saharan Africa. This experimental study, conducted at the Higher Institute of Technology of Mamou, aimed to evaluate and compare the performance of three solar dryer configurations integrating different thermal accumulators: charcoal, blackened body, and blackened sheet metal. The experiments focused on drying three tropical products (mango, banana, potato) during the dry season (April–May 2025). The measured parameters included temperature, relative humidity, absolute humidity, and air enthalpy at strategic points of the system (sensor inlet, drying chamber, outlet). The results showed that the configuration incorporating charcoal as a thermal accumulator reached the highest temperatures (average of 43.67°C, peak of 50°C at noon), significantly surpassing the configurations without charcoal (41.87°C) and with blackened sheet metal (40.13°C). Thermodynamic analysis revealed that the temperature in the drying chamber was consistently higher than at the inlet and outlet, confirming the efficiency of heat transfer. The complete drying times of the products varied between 2 and 3 days, with mango exhibiting the fastest kinetics. This study indicates that integrating materials with high thermal capacity, such as charcoal, can substantially improve the efficiency of natural convection solar dryers. The implications for rural electrification and enhancement of local agro-food production are discussed, with recommendations for system optimisation and large-scale deployment.