音波乾燥における恒率乾燥機構の考察

抄録

This paper describes the mechanism of sonic drying on the basis of the experimental results in the standing wave field during the constant rate period. It has been evident at present that the effect of sonic drying is related to the magnitude of the particle velocity, and appears obviously in case the particle velocity is above about 150cm/s. From the experimental results, it has become clear that the constant drying rate in sonic increases proportionally to the approximate square of the particle velocity, regardless of the magnitude of atmospheric pressure, sound frequency and air flow rate, and besides, under the condition of the constant particle velocity, the constant drying rate increases in proportion to the magnitude of atmospheric pressure. From the results above mentioned, it can be said that the increase of constant drying rate is related to the kinetic energy in sonic. It is possible to consider that this energy generates the frictional heat between the air with the particle velocity and the water surface of sample, and raises the temperature of the water surface, its saturated vapor pressure rises, therefore the constant drying rate increases.