A real-time predictive complementary relative phase shifting strategy for dual-port solid-state microwave heating process

Abstract

Relative phases between two sources can be precisely and dynamically controlled in dual-port microwave processes. Previously, a combined sweeping and complementary relative phase strategy was used to deliver more uniform heating than microwave heating processes using fixed or orderly sweeping relative phases. However, extensive relative phase sweeping (e.g., ∼44% of the 3-min whole heating time) is needed to collect relative phase-dependent thermal contributions to implement the complementary strategy. This limitation can be addressed by utilizing the constructive and destructive dual-port microwave interactions to develop a more efficient complementary strategy. Built upon the observation that the spatial microwave power dissipation density varies in a sinusoidal wave shape, this study developed a Predictive-Complementary relative phase strategy. Instead of collecting relative phase-dependent thermal contributions using extensive relative phase sweeping, the predictive approach only collected three thermal contributions at relative phases of 0°, 90°, and 180° and then predicted all others for implementing the complementary strategy. The predicted thermal contributions were validated by comparing them with the experimentally collected ones in dual-port microwave heating of gellan gel samples, which showed good correlations with R² values between 0.91 and 0.97 and Root Mean Square Error (RMSE) values between 0.17 and 1.02 °C. By comparing with other reported Fixed, Sweeping, and Sweeping-Complementary relative phase strategies, the Predictive-Complementary relative phase strategy devoted ∼83% of the 3-min heating time in the complementary shifting stage and showed the best microwave heating uniformity and power absorption efficiency. The Predictive-Complementary relative phase strategy presented an efficient approach to predicting relative phase-dependent thermal contributions for more uniform microwave heating using complementary relative phases. The algorithm can be integrated as an advanced relative phase heating strategy in smart solid-state microwave systems.