1. THE HEATING PRINCIPLE OF MICROWAVE
Microwave is one kind of radio wave whose wavelength is very short, frequency is very high. Therefore, it is called ultrahigh frequency electromagnetic wave. Microwave can heat food mainly result in the mutual affect of the food in the microwave field and the microwave field itself.
Under the affect of microwave field, the thermal effect mechanism produced from the mutual affect of the microwave and the food includes two aspects. One is Dielectric loss of polar molecule; the other is conductive loss of ion.
Usually, food is constituted of organism (plant and animal). The organism is formed by all kinds of polar water molecule, polar protein molecule, and all sorts of saltion. The center of gravity of the positive and negative charge in the molecule is not coinciding. In normal condition, the molecule is in irregular order due to its thermal action, thus the food do not appear polarity.
(a) | (b) | (c) |
Fig.1-1
Apart from the above said action, there is another action which is electric ion under the action of microwave field, act fiercely accompanied with the acceleration of electric field. The positive ion transfer to the negative polarity of the field while the negative ion does opposite. Accompanying with the changing electric field, the electric ion hanging accordingly. During the transferring, heat produced with the crash among the ion. This kind of action takes the main effect to those microwaves heating of high salt molecule.
No matter it is the polar molecule swaying or the ion transferring, they both are turning the microwave energy which the heating matter got from the microwave field to heat energy. From the analysis of theory, we can draw such a conclusion that the power which a unit of volume matter absorbed from the microwave field as the following formula:
Pa=KE fErtgδ
Pa Stands for the power the heated matter adsorbed from the microwave field.
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