Heat Energy Requirement Analysis In Coffee Bean Drying Using An IoT-Based Solar Dryer Dome

Abstract

Coffee is one of Indonesia’s leading plantation commodities, including in Central Lombok Regency, which has a high production potential. The drying process is a crucial post-harvest stage to maintain coffee bean quality by reducing the moisture content to the ideal range of 12–13% according to the Indonesian National Standard (SNI). However, traditional sun drying methods are highly weather-dependent and often reduce product quality. This study aims to analyze the heat energy requirements, drying efficiency, and the role of latent heat during the coffee bean drying process using an IoT-based Solar Dryer Dome. The research employed an experimental method with solar radiation and forced convection drying systems equipped with SHT31, BH1750, DS18B20, and Soil Moisture SEN0308 sensors, controlled by an ESP32 microcontroller integrated with the ThingSpeak platform. The results showed that the total incoming heat energy was 191.426,568 MJ, useful heat energy 31.321,9808 MJ, heat losses 190.020,549 MJ, and stored heat 1.405,9742 MJ. The drying efficiency reached 16.36%, with the moisture content decreasing from 65.32% to 11.16%. Part of the absorbed energy was used as latent heat of vaporization to convert water within the coffee beans into vapor, while the release of this latent heat contributed to the increase in outlet air temperature. The IoT-based Solar Dryer Dome effectively accelerated the drying process, maintained coffee bean quality, and enabled real-time monitoring of drying conditions.