Effects of polarization-charge shielding and electromagnetic resonances on water behavior under microwave heating

Microwave heating of water-rich solvents is a widely used processing technique in research and applications. High-quality outcome requires a uniform temperature environment; which, in turn, depends on the balancing of a variety of effects taking place during the heating. Here, we show that two inher...

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Veröffentlicht in:Physics of plasmas 2023-12, Vol.30 (12)
Hauptverfasser: Liu, L. C., Liang, J. C., Chen, K. W., Chu, K. R.
Format: Artikel
Sprache:eng
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Zusammenfassung:Microwave heating of water-rich solvents is a widely used processing technique in research and applications. High-quality outcome requires a uniform temperature environment; which, in turn, depends on the balancing of a variety of effects taking place during the heating. Here, we show that two inherent effects, namely, polarization-charge shielding and electromagnetic resonances, play a critical role in shaping up the field pattern in the heated water sample. Polarization-charge shielding produces an internal electric field sensitive to the sample size, shape, and orientation. Internal electromagnetic resonances result in a widely varying electric field, while also allowing much deeper field penetration than the attenuation length to allow large-scale treatment. The key to temperature uniformity, thus, lies in an optimized thermal flow to balance the non-uniform energy deposition. These complicated processes are examined in simulation and interpreted physically. It is shown that a spherical sample is most favorable for obtaining a high temperature uniformity mainly because of its rotational symmetry. This conclusion is significant in that prevailing sample vessels are mostly non-spherical.
ISSN:1070-664X
1089-7674
DOI:10.1063/5.0172258