Kazuko Takeshita

Prediction of temperature and moisture content profiles of paper in a drying process

A drying process of paper on a heated roll and covered by a canvas was calculated based on a one-dimensional model which concerns nonsteady heat and mass transfer in the direction of paper thickness. The calculation could reproduce measurements of changes with time of temperature and moisture content profiles in the paper, and revealed the following details of the drying process. The drying of paper proceeds from the roll side. A marked distribution of temperature comes out in the direction of paper thickness in the region where the liquid water outside of the cell membranes has evaporated and where there is no feed of water by capillary action. As the drying proceeds with time, this region, at the front of which the evaporation rate takes a maximum, expands to the canvas side. Another maximum evaporation rate is always found at the surface contacting the canvas.