A dynamic complementary relative phase heating for increasing microwave heating performance in dual-port solid-state based microwave heating

Solid-state microwave heating, particularly dual-port systems, presents a promising alternative to conventional magnetron-based microwave ovens by offering dynamic control over relative phases to enhance heating uniformity. This study explores the evolution of a predictive complementary relative phase shifting strategy through three stages: development, optimization, and validation in real food products.

In the initial phase, a combined-sweeping and complementary relative phase shifting strategy was introduced to improve heating uniformity. By sweeping relative phases between two microwave ports from 0° to 315° in 45° [degree] intervals, relative phase-dependent thermal contributions were identified. Complementary relative phases were then selectively applied during heating, achieving superior uniformity in a model food, gellan gel, compared to fixed or sweeping-only strategies.

Building on these findings, the second phase aimed to optimize the approach by reducing the extensive sweeping process, which previously occupied about 44% of the heating time. A Predictive-Complementary relative phase strategy was developed, leveraging the sinusoidal variation of spatial microwave power dissipation. Instead of full-phase sweeping, only three relative phases (0°, 90°, and 180° [degree]) were measured, and a predictive model was used to estimate all other thermal contributions. This approach increased the complementary shifting duration to about 83% of the heating time, significantly improving heating uniformity and energy absorption efficiency. The model was validated with high correlation (R² [R-squared] = 0.91-0.97) and low RMSE [Root Mean Square Error] (0.17-1.02°C).

Finally, the strategy was tested in real commercial food products to assess their effectiveness beyond model foods. Five food products, ranging from single components to multicompartment meals, were evaluated. The strategy consistently improved heating uniformity and energy absorption efficiency in most cases, with the highest gains in single-compartment foods like lasagna and beef in gravy. However, uniformity improvements varied with food structure, as steam-venting packages and food weight influenced heating performance.

Overall, the predictive complementary relative phase shifting strategy demonstrates a robust and efficient approach for next-generation solid-state microwave ovens, enabling more precise and uniform heating across diverse food matrices. This study highlights its potential for practical applications in commercial food reheating, paving the way for intelligent microwave heating solutions.