Abstract

Adequate and suitable controlled atmosphere plays an important role in post-harvest yam tuber storage environment for sustaining the quality and quantity of yam tuber especially in a reputable country that produces largest quantities of yam in the world. The effect of post-harvest loss is caused due to lack of appropriate storage systems and these had been the most common problem faced by small-holder yam farmers. In order to avoid post-harvest losses and food wastages due to poor atmospheric condition in West Africa, this paper proposed a microcontroller based Proportional Integral Derivative (PID) controller for controlling the temperature and humidity of yam tuber post-harvest storage. The due technique would maintain a relatively constant temperature and humidity in a storage chamber so as to minimized high level of yam postharvest losses that has become a serious economic and food security threat in West Africa. Some mathematical equations were formulated based on temperature and humidity storage chamber models using heat and energy balance principles. The models were designed using Proteus tools and simulated in Simulink form. The parameters of PID controller were tuned with Ziegler Nichols to achieve a desirable steady state response. The system performances were evaluated in settling time, temperature and humidity set point tracking. The performance metrics were compared with existing technique of Fuzzy Logic Controller (FLC). The sensitivity of the results justified that proposed technique gave a better performance in terms of decreased in settling time, temperature and humidity.

Key words: Yam storage, PID controller, temperature, humidity control