Abstract:
Tea withering is a critical stage in black tea production, directly affecting the quality, flavour,
and aroma of the final product. In many Sri Lankan tea factories, this process is still monitored
manually using conventional methods, leading to variability, inefficiency, and labour dependency.
This study presents the design and development of an automated, real-time monitoring
and control system to optimise the tea leaf withering process using Internet of Things (IoT)
technology. The system utilises an ESP32 microcontroller integrated with waterproof DS18B20
digital temperature sensors and a capacitive moisture sensor to measure dry and wet bulb temperatures
and leaf moisture levels. Based on calculated temperature depression, the system
automatically adjusts airflow through servo-controlled louvres. When the depression exceeds
5 ◦C, fresh air louvres fully open and hot air louvres partially close; if leaf moisture falls below
60%, hot air louvres close completely to avoid over-drying. Conversely, if the depression
is below 5 ◦C, both louvres open fully to increase airflow. Real-time feedback is displayed
on an LCD, while alarms and cloud-based logging via ThingSpeak enable continuous monitoring
and analysis. A custom mobile application further supports remote access. Prototype
testing at Sisiramba Tea Factory demonstrated improved uniformity, reduced manual intervention,
and enhanced energy efficiency. This system offers a scalable, cost-effective solution for
modernising tea withering in Sri Lanka.
