Abstract

The increasing demand for energy and the limited availability of diesel fuel have encouraged the development of biodiesel as a renewable energy source. Temperature stability during transesterification is important because it affects reaction performance and biodiesel yield. This study aimed to experimentally compare conventional PID, adaptive PID, and hysteresis temperature control in a laboratory-scale biodiesel reactor. The system was tested using palm oil and castor oil at setpoints of 50°C and 60°C with conventional PID, adaptive PID, and hysteresis control. Each combination of control method, feedstock, and temperature was evaluated in a single experimental run. The system consisted of a Type-K thermocouple, temperature controller, solid-state relay, heating element, magnetic stirrer, RS-485 module, and computer. Performance was evaluated based on rise time, overshoot, settling time, steady-state error, density, and yield. Under the tested conditions, adaptive PID produced no overshoot and showed the lowest observed controller-indicated steady-state error of 0.056°C. Hysteresis control produced the shortest rise and settling times but showed the highest observed steady-state error of 0.625°C and overshoot under several conditions. The highest observed yield in the single-run experiments was 95.423%, obtained from castor oil at 60°C using adaptive PID.