Solar photovoltaic (PV)-driven active crop drying system for plantain (MUSA SPP): Design, development, and performance evaluation

A solar photovoltaic (PV)-driven active crop drying system comprising a solar air heater, a three-tray drying chamber and a data logger was designed and fabricated. Drying system is equipped with three DC fans of 18 W each, powered by 150 W mono-crystalline, solar PV module, and 180 Ah deep cycle battery storage. Purpose-built data logger constructed with a 60-pin Arduino-mega microcontroller and equipped with a digital dual-display screen was used to acquire real-time data on relative humidity and temperature at vital points in the drying system. Performance evaluation of the dryer was carried out while studying the drying characteristics of plantain chips at three thicknesses of 0.7, 1.0, and 1.5 cm. Drying characteristics were presented in graphs of moisture content (MCdb) versus time, moisture ratio (MR) versus time, and drying rate (DR) versus time for the different trays. Final moisture contents of the plantain chips were 10, 14, and 21% for the 0.7, 1.0, and 1.5 cm, respectively, in the three trays. The higher figures for the 1.0 and 1.5 cm levels of thickness are attributable to case hardening. Results showed that drying proceeded mainly in the falling rate period. Graphs of MR and DR showed that the drying process was more effective as the chips became thinner. Evaluation of 10 thin-layer drying models carried out using the acquired data showed that the Wang and Singh model was the best suited for describing the drying characteristics of plantain. Practical applications The results of the present work will be very useful to food processing companies producing Plantain chips for local consumption and export. A good knowledge of the best suited thin-layer drying model will help to predict the MR (and hence MC) as a function of drying time. In this way, energy might be saved and product quality guaranteed. In addition to quality assurance applications, the effect of layer thickness on drying characteristic would be very useful in prescribing the optimal thickness of the chips being processed.