No-load Testing of the Modified Auxiliary Heating System for BAU Solar Chimney Dryer

Experimental analysis was conducted to evaluate the performance of a modified electric auxiliary heating system for a natural convection solar dryer without load. The dryer operated using heat from two sources for drying operation. This study focused on describing the temperature profile inside the dryer and the airflow velocity of the modified auxiliary heating system at no-load. Microcontroller (ESP32) automation was integrated within the auxiliary heating system to maintain the recommended temperature range for drying agricultural products. The experiment was conducted during low sunshine season and the maximum solar radiation was 336.56 W/m2. The average airflow velocity from each column of holes was found to be in the range of 2.33 m/s to 2.80 m/s. From the test, the obtained drying temperature was sufficiently higher above ambient air temperature to continue drying. A maximum rise of 29.7 °C above ambient was found at 2.00 pm. The second drying chamber had slightly high temperature values due to the stagnancy of hot air in it. The auxiliary heater showed promising performance towards a weather-independent drying operation. However, it needs to be improved in capacity to raise the air temperature to the required range. Further study on the dryer design for better exhaustion system alongside uniform airflow rate is also recommended. Integrating IoT-based solutions will make the drying process smarter and reduce drudgeries during the operation.