Enhancing uniformity and energy efficiency of microwave heating for different cavity loads: Frequency-shifting strategies using feedback signals from solid-state microwave generators

Novel solid-state generators offer precise control of the microwave field, a valuable capability for increasing energy efficiency and uniformity of heating through tailored frequency-selection strategies. Recent research, however, overlooks to test the adaptability of promising strategies to different microwave cavity loads. However, adaptability is crucial for real-world applications. Our study compared the performance of various strategies in the context of different microwave cavity loads, using cylindrical Gellan gel samples of 130 g and different diameters from 50 mm to 200 mm. Strategies using frequency-dependent feedback signals gathered by the microwave generator itself excelled in identifying optimal excitation frequencies across all investigated heating scenarios. These feedback signals identified resonant frequencies specific to each load before heating, enabling excitation at all resonant frequencies and achieving maximum uniformity at high energy efficiency. Additionally, feedback signals helped identify the most energy-efficient product before heating trials. In summary, detecting sample feedback before processing via the solid-state generator itself allows tailored responses to individual heating tasks of the microwave oven user.