Modelling and energy efficiency analysis of the microwave continuous processing of limestone

Our numerical investigation is oriented to the energy efficiency of the microwave heating technology for the continuous production of cement clinker. Simulations of the novel microwave continuous processing of limestone are performed using the COMSOL Multiphysics® Software. The proposed mathematical model couples Maxwell’s equations with energy and chemical equations, and numerical verification and validation are undertaken to support the accuracy of the results in this work. This approach includes automatic control actions regulating energy input and cavity impedance. A rectangular waveguide, operating as a single-mode cavity at 2.45 GHz, is utilized. The impact of various fill ratios of material on the system’s efficiency unveiled an intriguing heat transfer mechanism responsible for optimal operational conditions, with microwave efficiency up to 75% and thermal efficiency exceeding 90%. Notably, the potential of microwave technology in reducing greenhouse gas emissions is contingent upon establishing clean energy sources for electricity production. •Impedance control and predefining power are essential for maximum efficiency.•The material’s velocity and the electric field’s sinusoidal variation should be aligned.•A unique heat transfer behaviour emerges from the coupling of the physics involved.•Eq. 14 describes the interplay of the maximum temperature and electric field.•Optimal conditions achieved 75% MW efficiency and over 90% thermal efficiency.