Precise Temperature Control Strategy for Laboratory-Scale Fermentation Process

This paper presents a precise temperature control strategy for a laboratory-scale fermentor system. The proposed method utilizes actuators employing a hysteresis on/off cooling mechanism and a proportional derivative (PD) control algorithm enhanced with range-time proportional heating control. The objective of the control strategy is to achieve a stable point temperature of 28 to $30 ^{\circ}\mathrm{C}$ within the fermentation chamber, with a maximum steady-state error allowed at $1 ^{\circ}\mathrm{C}$. Experimental results demonstrate the effectiveness of the proposed control method in accurately regulating the temperature inside the fermentation chamber. The system achieves the desired temperature in 3600 seconds when cooled with a set point of $30 ^{\circ}\mathrm{C}$, but takes 5 times longer with the lowest set point of temperature, with a maximum overshoot of less than $0.3 ^{\circ}\mathrm{C}$ or 1% from the operational set point and a steady-state error of $0.25 ^{\circ}\mathrm{C}$. Future research can further enhance the stability of the fermentation process by incorporating optimal tuning methods. The developed precise heating control strategy has practical implications for the laboratory-scale fermentor, contributing to improved process efficiency and product quality. It also provides the foundation for potential applications in larger-scale industrial fermentation.