A Temperature-Control System for Continuous-Flow Microwave Heating Using a Magnetron as Microwave Source

A real-time temperature control system is designed for microwave heating of a continuous-flow substance. In this system, a magnetron is used as the microwave source, and its output power can be continuously adjusted though circuit design. A programmable logic controller (PLC) is used to procedure the temperature and power data as well as lead the whole control decision. The sample temperature can be controlled by regulating the output power of the magnetron though the control signal from the PLC during the heating process. The complete system is finally assembled into a user-friendly device, where the users can operate and monitor the heating process conveniently though a touch screen. A temperature-dependent material (Phosphoric acid) is used in system tests. The results show that the designed system can successfully achieve the desired temperature with an acceptable accuracy and stability.