Hot air is an essential resource in almost all food processing industries. The temperature and volume flow rate of the air is an important control parameter. These parameters directly affect the quality of the end product. Therefore, in some processes, the precise control of these parameters is a mandatory requirement. A PID-based system is designed and tested for presice control of the airflow temperature in the present research.
The system contains mainly a PID controller ( NC 2438), feedback sensor and heater control circuit. The system is straightforward to assemble. The user can set the close to a wide range for controlling the air temperature. The output of the system indicates the very precise control of air temperature in the range of 0.1OC. This system works very well for airflow up to 300 CFM. The main limitation of the system is that as airflow increases beyond 550 CFM, precise control was not possible. In this case, the PID needs to set temperature range ±2OC to trigger the heater control circuit.