Analysis of capacitive measurements at low frequencies for moisture content determination in soybeans

Abstract

This study aims to evaluate the capacitive measurement method at low frequencies for determining the moisture content in soybeans. Furthermore, a technique for measuring the moisture content of soybeans at different temperatures is proposed. A practical cylindrical capacitor was designed for the experiments. Capacitive measurements at frequencies of 1 kHz, 10 kHz and 100 kHz were performed using an LCR meter. Two varieties of soybeans were used in the tests, and the differences were evaluated. The errors of the proposed method were analyzed, and the correlation between moisture content and capacitance was verified. The influence of temperature on the measurements was also quantified. Polynomial models are proposed to compensate for temperature variations. It was found that reasonable precision can be achieved at 100 kHz using the temperature compensation provided by the designed models.