Microwave moisture sensing system in drying process for green tea production

Abstract

A microwave moisture meter used in a drying process for green tea production is described. It can measure the leaves of green tea containing the moisture of 40 to 100 percent in dry basis. It is a transmission type of 9.4 GHz waves. To eliminate the variation in the layer thickness the sample weight is controlled. The moisture content is obtained from the ratio of the microwave attenuation to the weight of the leaves. Averaging the data with a computer the moisture content were measured in the error of 3% of moisture values. It is better than the error of the conventional measurement by the feeling of a skilled workman's fingers actually used in factories.<>