Design, manufacturing and test of a mixed-mode solar dryer for food products

This work was focused on the experimental study of a mixed-mode solar dryer. This dryer is designed and manufactured at the mechanical engineering department of ISSAT Kairouan. Mainly a solar collector, a drying box equipped with three trays for crops and covered with a transparent glass cover, a chimney, composes it and it is equipped with an electric air fan. The presented dryer is characterized by two coupled heat transfer modes; convective heat transfer and direct solar radiation to dry the food products. The solar dryer is tested in Kairouan city during June 2022 and applied to dry two food products, red pepper and banana. The experimental results are acceptable and the system present high thermal efficiency and short dying time from 4 to 7 hours. Compared to conventional convective drying in a tunnel dryer, the solar system can save a lot of energy and reduce the drying time considerably. Moreover, the final quality of the dry products is acceptable for human safe consumption.