Measuring Model for the Gravimetric Method by Drying in N-Stages Applied to Materials with High Moisture Content

Abstract

The gravimetric method by oven drying is widely used for moisture measurement in solid materials following a drying protocol which includes specific conditions such as drying time and temperature. Although this method is reliable for many types of materials, there are some cases where materials with high moisture content require a pre-drying process at low temperature before performing the final drying. Some examples of such materials are freshly harvested grains which cannot be grounded according to the typical drying protocol. In these cases, the drying process can be applied in several stages to reach a favorable grinding condition. The measurement model for the moisture content determination using N-stages of drying can be derived from the definition of moisture content. Based on this, in this paper, a model to obtain the moisture content in N-stages is presented. The model was applied to samples of corn and wheat by drying in several stages, obtaining comparable results. According to this model, the moisture of the sample only depends on the initial mass and the mass after the final drying stage. The equivalence in the measured results was verified calculating the normalized error. Also, the estimation of the uncertainty was carried out.