Studies on the measurement of grain moisture using high frequency coil (part 1) The relationship between grain moisture and inductance of coil

• Published in: Nogyo Shisetsu (Journal of the Society of Agricultural Structures, Japan) Vol. 29; no. 4; pp. 181 - 186
• Main Authors: LI, Zaigui, FUJIKI, Tokumi, UCHIDA, Susumu, INABA, Shigeki
• Format: Journal Article
• Language: English
• Published: The Society of Agricultural Structures, Japan 25.03.1999
• Subjects: coil; high frequency; inductance; moisture content measurement; relative magnetic permeability
• ISSN: 0388-8517; 2186-0122
• DOI: 10.11449/sasj1971.29.181

The aim of this study was to develop a method to measure moisture content in real-time in the drying and processing of grain. High frequency (100-1000kHz), close and limited coils were used as sensors for grain moisture. It was found that response of coil to the moisture content was affected by the three essential elements (rolls N, diameter D and length l) and frequency. The optimal measurements of moisture content were obtained by using coil G (N=180, D=75mm, l=108mm) with 1000kHz. Relative magnetic permeability and inductance of coil varied with frequency and grain moisture. We found the regression equations between inductance and moisture for rice and wheat. In particular, when moisture was in range of 15%-30%, the moisture content could be estimated accurately, with relative error less than 2%.