A combined-sweeping & complementary-relative-phase strategy to improve heating performance in a dual-port solid-state microwave system

Dual-port solid-state microwave heating could address the single-port low microwave power issue and potentially result in better microwave heating performance. This study developed and evaluated a combined-sweeping & complementary-relative-phase-shifting heating strategy for dual-port microwave heating of foods. The combined-sweeping & complementary-relative-phase-shifting strategy first orderly swept the relative phases between two ports from 0° to 315° at an interval of 45° operated at a frequency of 2.45 GHz and a power level of 200 W for each port to determine relative phase-dependent thermal contributions. Then, relative phases that have complementary thermal contributions to the real-time heating results were determined and used in the heating process. The performance of microwaving a tray of 300 g gellan gel model food for 3 minutes was compared with that of the fixed-relative-phase and orderly-sweeping-relative-phase strategies. The results showed that the complementary strategy delivered significantly more uniform heating results (HUI = 0.27 ± 0.01) than the other strategies. Similar microwave power absorption and maximum and minimum temperatures were observed in the complementary and orderly sweeping heating strategies, which was better than the fixed heating strategy. Overall, the complementary strategy showed superior heating uniformity, followed by the orderly sweeping and then the fixed-relative-phase heating strategy. The complementary relative phase shifting strategy is promising to be incorporated into solid-state microwave systems for smart heating processes.