One of the most crucial methods for preserving agricultural produce is solar drying. The major focus of this paper is increasing solar drying systems' effectiveness. The development of new methods and variables that may have an impact on the functionality of solar dryers aids in enhancing their efficiency. An indirect-type solar dryer for drying agricultural products is proposed and developed in this study. A dryer consisting of a solar flat plate air collector, an insulated drying chamber, an auxiliary (electric) heat source, and an electric fan is constructed to improve the dryer's performance. The dryer's most typical function is to blow hot air at the product, forcing the water in it to evaporate. The effect of air temperature and velocity on evaporation rate has been studied experimentally. Tests with three different airflow rates—0.042, 0.0735, and 0.105 m3/s—are conducted. When there is little or no solar radiation, an auxiliary heater is used to provide sufficient heat. For varying airflow rates, solar mode and electrical mode were tested experimentally with only one energy source in each mode. The findings revealed that using a different heat source in addition to solar radiation will allow you to keep the air temperature in the drying chamber between 32oCand 42oC. Also, it was found that for the whole drying process at high air velocities, the temperature had less influence on the dryer's performance.

Temperature and relative humidity are the key control parameters in drying processes for preserving and improving food quality. To achieve this goal, an automatic control system has been designed and built to provide adequate heat and drying streams according to the ambient requirements of various climatic zones and the kind of dried product. The control system combined with sensors allows the temperature and humidity of the drying chamber to be adjusted online by predetermined parameters. When there is little or no radiation present or when rapid drying rates are required, the heated air stream may be produced utilizing an electric motor fan in addition to an electrical backup heater. The fan automatically modifies its speed using the Pulse Width Modulationtechniquefor energy efficiency depending on the required temperature of the drying chamber. The control system based on Arduino Uno board is built within the solar dryer, after which tests are carried out. The test results are displayed on a display. Themanagement system was set up to maintain an ambient temperature between 40 and 60 °C andrelative humidity between 10 and 20 %. The system is a flexible solution for different climatic zones and dried products, according to experimental findings demonstratingits efficiency in managing the drying environment. Finally, this paper can conserve energy because it only works when the temperature around the food is below 60 oC.