Multi-physical field analysis based on a multi-material mode stirrer and interlayer for microwave processing fluid

•Mode stirrer in microwave reactor kettle may play a positive role in microwave heating.•The microwave heating characteristics can be altered by the dielectric properties of the materials used in the reactor structure.•Appropriate reactor parts material can improve microwave energy absorption and enhance heating. Microwave technology is widely recognized for its efficiency in the chemical, food and energy industries, and has attracted great attention due to its ability to induce both thermal and non-thermal effects. However, the use of microwave reactors often leads to thermal runaway phenomenon. To address this challenge, a multi-material mode stirrer has been integrated with a microwave reactor structured with an interlayer, and the materials of mode stirrer and interlayer inner wall have been changed to address issues related to temperature uniformity. The combined effects of multi-material mode stirrer and different material inner walls on the microwave heating characteristics have been studied by using the evaluated coefficient of temperature variation (COV) and the mean fluids temperature. It is discovered that: (1) the effect of mode stirrer on heating characteristics depends on its material and the coefficient of temperature variation of Aluminum-Alumina mode stirrer is reduced by 44 %; (2) under the action of mode stirrer, the corundum inner wall can improve the heating efficiency, but the glass inner wall has a poor effect on it; (3) changing the structure materials of the microwave reaction kettle has little effect on the heating efficiency and the combination of Polyethylene-Aluminum mode stirrer and silicon carbide inner wall can improve the heating uniformity.