High-efficiency and compact microwave heating system for liquid in a mug

Abstract

The demand for efficient and compact heating for dynamic dielectric liquid has grown significantly. Compared with traditional heating, microwave heating has the advantages of being fast and efficient. Moreover, the demand for outdoor portable heating and industrial compact heating is increasing. To address this limitation, this study proposes a compact heating system based on a metamaterial-based circular waveguide. First, asymmetric propagation theory is introduced, and an asymmetric propagation circular waveguide is designed in detail according to the discretisation of the relative permittivity. Then, a multi-physics model using a circular waveguide and a mug for high heating efficiency is developed by coupling Maxwell's equations and the heat transfer equation. Furthermore, heating experiments are performed for liquids with different relative permittivity and the experimental results consistently validated an efficiency rate of over 88 %, which agrees with the simulation results. Finally, the effects of the dielectric properties of the material and mug on the heating efficiency are discussed to highlight the robustness of the proposed heating system, with heating efficiency consistently maintained at 75 % or higher. In summary, the proposed design features a compact structure that is suitable for practical microwave heating applications.