Technical Performance of an Inflatable Solar Dryer for Drying Amaranth Leaves in Kenya

• Main Authors: Sebastian Romuli, Steffen Schock, Marcus Nagle, Christine G. Kiria Chege, Joachim Müller
• Format: Article
• Language: English
• Published: MDPI AG 2019-08-01
• Series: Applied Sciences
• Subjects: off-grid; photovoltaic; postharvest; renewable energy; Simulink; solar bubble dryer
• Online Access: https://www.mdpi.com/2076-3417/9/16/3431

The technical performance of an inflatable solar dryer (ISD) to dry amaranth leaves (<i>Amaranthus</i> spp.) was investigated. To handle the drying of lightweight materials, modification was made by adding an air deflector and trays inside the ISD. Computational performance of the ISD solar energy system was evaluated using MATLAB Simulink. The estimated air mass flow in the inlet of the ISD was 0.75 kg/s. Using computational fluid dynamics (CFD), the uniformity of air distribution in the ISD was evaluated. The solar radiation reported during good drying performance ranged between 510 and 950 W/m². In a controlled charging system, a 100 W_p PV module typically generated voltage between 10.22 and 18.75 V. Drying conditions at temperatures of 40 &#176;C or above were typically achieved in the ISD from 12:00 to 16:00. Temperature inside the ISD could reach up to 69.4 &#176;C during the day and 13.4 &#176;C during the night. The highest relative humidity of 97.4% was recorded during the night. Opening the ISD while mixing the product could lead to considerable heat loss. Fluctuation of solar radiation and shaded areas in the ISD appeared to be the major factors affecting the drying performance.