Modification of condenser-type moisture meter.
1988
Noh S.H. | Kim W.T.
In attempting to improve the performance of existing condenser-type moisture meter, the effects of grain moisture content, temperature and bulk density on the frequency were analyzed with a LC oscillator covering 4-5 MHz and with a RC oscillator covering 5-11 MHz. Based on those results, a new caliberation model for the measurement of moisture content was developed. Also, the performances of the prototype moisture meters were compared with a few commercial meters. The frequencies of the oscillators were linearly decreased with the grain temperature within a given moisture density which was defined as the product of moisture content and bulk density. Also, the moisture density gave negative effect to the frequency. There was difference in the coefficients of temperature compensation when the grain temperature was subjected to change under constant room temperature and when the grain and room temperatures were kept at the same and changed. The frequency was negatively affected by the grain moisture and bulk density, respectively, and indicated negative linear relationship with the product of those two factors defined as the moisture density. The prototype moisture meter consisted with a LC oscillator was the best in precision as compared with the other commercial moisture meters. The mean and standard deviation of differences in moisture contents measured by the prototype and dry oven were 0.27% and 0.32%, respectively.
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