Establishment and application for diffusion model of moisture in drying process of pressboard

In this paper, a capacitive sensor is used to monitor the dielectric response of the pressboard and to calculate the moisture content in the pressboard by using calibrated expressions. The structure of the capacitive sensor and experiment system are introduced. The kinetics of the drying process is discussed. Models of moisture content diffusion and application of the drying kinetics of pressboard and of multilayer pressboard are presented, and the rate of the series convergence of models is high and accuracy is suitable, which provide a theoretic basis for the on-line moisture measurement in transformer industry. Based on the diffusion equations and their initial and boundary conditions, the distribution of moisture is calculated during the experiments, and the models developed for mass transfer inside the pressboard is validated for a one-dimensional case and a two-dimensional case. The result is helpful in reasonable design of production technology.