DEVELOPMENT OF MICROCONTROLLER - BASED STORAGE CHAMBER FOR WATERMELON FRUITS (CITRULLUS LANATUS) GROWN IN NIGERIA
Abstract
Watermelon fruits rapidly deteriorate after harvest because of its short shelf life of about 10 days, after which it loses its nutritional value. Hence, the development of a microcontroller based storage chamber for watermelon fruits. The chamber is a combination of the cooling, power supply, microcontroller circuit, and sensors units for controlling the atmospheric parameters. The storage chamber was designed to keep the atmospheric conditions at temperature of 10-15, relative humidity at 90%, oxygen and carbon dioxide concentrations at 2% and 3% respectively. The chamber with an area of 1456cm2 and a height of 41cm was designed to store 20kg of water melon. The cooling unit incorporated a compressor of 0.1hp. An ATmega328P microcontroller programmed in C++ was developed with the Isis Proteus software for the design and simulation. The microcontroller was interfaced with the DHT11 sensor, valves, power supply and a liquid crystal display. Cooling test was carried out on the system and a temperature of 1oC and humidity of 90% was recorded at a time of 55 minutes. An average voltage of 4.07V was measured at the microcontroller interface with the sensor when temperature and humidity level were 12 and 90% respectively. Tests were carried out on the system and the result was a controlled environment characterized by temperature of range 10oC -150C and 90% relative humidity. The relationship between temperature and humidity with time and output voltage respectively were determined using Matlab software. The results showed that the chamber will increase the shelf life of watermelon fruits
