Design and construction of an electric automatic grain dryer :

Abstract

Electric Automatic grain Dryer is designed to solve maize grain loss issues that emerge due to reliance on traditional grain drying methods such as open sun drying method. It is designed in such a way that moisture content and drying temperatures of grain are monitored and controlled by Arduino microcontroller. The machine is designed to dry 100kg of wet Maize per batch at initial moisture of 28%. It has the drying chamber of 60 cm in height and 60cm diameter. The machine has cylindrical bin with two layers having cotton waste as an insulating material, slanting and perforated floor. And a shaft placed at the Centre of the cylinder with the spikes at alternate sides to each other serves as a stirrer that is driven by 4Hp three phase motor. In this dryer, grains are manually recharged into drying chamber. The hot temperature needed to evaporate the water content in the grain for maximum results is in the range of 350C - 600C (Waqi’Ah & Raafi’U, 2023). Airflow plays an essential role in maintaining the relative humidity of the drying chamber. Low humidity will result in faster heat transfer. The grain drying process requires heat transfer to evaporate the water contained in the grain. The air blown by the blower carries water vapor around it. The use of sensors allows the measurement of temperature, moisture content and relative humidity of the grain mass. In addition, the Arduino controls the sequencing of blower motor and heat gun motor. Sensors that were used are temperature and moisture and they act as the input to the Arduino. The temperature sensor ensures that the grain’s drying temperature doesn’t exceed the prescribed limit. The moisture sensor measures the moisture content of the grain. The controller (Arduino) gives the switching commands to blower, and heat gun through the sequential control program entered in memory of Arduino, by the user as per their requirement. After attaining the required final moisture content (about 13%), the controller stops the blowers and air heaters and turn on a buzzer to alert the farmer that grain is ready. However stirrer continues running for some time until when the grain cools and then it is manually stopped by farmer. The grains are collected and the new set of grains is put and then the process repeats.