Measurement of the Moisture Content in Woodchips Through Capacitive Sensing and Data Driven Modelling
Jing Yan, Wenbiao Zhang, Yong Gang Yan · 2020
Woodchips as a common biomass are widely used in industrial processes and our daily lives. The moisture content in woodchips has a significant effect on the processing and combustion efficiency of woodchips. Therefore, it is necessary to develop a suitable method to measure the moisture content of woodchips. Capacitive sensors are widely used in various fields due to their simple structure, low cost and non-destruction to the samples. Because of the uniform sensitivity distribution compared to the parallel plate sensor design, a helical capacitive sensor is used in this paper to measure the moisture content of woodchips. The structure of the sensor is firstly optimized based on the orthogonal test method using a finite element model. Then, the influence of particle size and packing density of biomass on the capacitance readings is investigated. Finally, the moisture content is predicted through data driven modelling. Woodchip samples with different particle sizes, moisture content and packing densities are used to verify the model. It is found that the relative error between the predicted and reference values is within ±10% over the range of moisture contents from 7% to 49%.