Designing An Automatic Microcontroller-based Drying Machine of Coffee Beans

Abstract

This research aimed to create an automatic microcontroller-based coffee bean drying machine without the support of sunlight to produce SNI-standardized coffee beans with small water content or amounted to 12%. The appliance consists of a tubeshaped container with 50 cm length and 11 cm radius, soil moisture sensor, DS18B20 temperature sensor, heater, motor DC, relay two-channel, and Arduino Uno microcontroller. The drying works when soil moisture sensor detects 12% of water content from big coffee beans. The drying process is done by applying a heater to dry the coffee beans, and the motor DC is used as the rotator of the container to dry the coffee beans evenly. The temperature of the drying container is around 51°C-55°C because the surface of coffee beans will be damaged if the temperature is above 55°C. When the water content of coffee beans is low or equal to 12%, the drying process is terminated. The drying process of dense coffee beans (1 kg) with 25.34% of initial water content takes 60 minutes with 11.74% of final water content as a result, While the drying process with the help of sunlight required approximately 310 minutes with 11.83% of final water content. It has been proved that the drying with the machine was faster than the drying process through sunlight.