Influence of Three Phases of Soil on the Drying of Soil Moisture by the Microwave Heating

摘要

In this paper, two clays, Umeda clay and marine clay of Osaka group, were used for an investigation of the usefulness of the microwave oven for water content determination. Comparisons of water contents determined using the microwave oven and the conventional oven showed negligible or no difference. The change in drying time according to the dielectric constant was taken as a measure of the effect of heating by microwaves. As the dielectric constant of liquid phase was about 20 times larger than the one of solid phase, consequently, a coefficient of correlation between initial liquid ratio and drying time was high; and also the one between initial solid ratio and drying time was low. However, though the dielectric constant of vapor phase is small, under the influence of drying time required for the range of low water content due to mainly water movement in the state of vapor (corresponding to gas diffusion), a coefficient of correlation between initial vapor ratio and drying time is negative and comparatively high.