Moisture and temperature measurement of paper in the thickness direction

In this work the z-directional moisture and temperature profile of fine paper was studied during drying. The goal of this research was to determine moisture gradients in thickness direction during drying. This information is needed to improve existing drying models as well as to help deepen the understanding of the drying phenomena and its effects on paper structure. The gradient information can be directly used in the drying models and will assist in making more accurate estimations of the capacity and quality effects of drying on paper. For this study a new method for measuring the z-directional moisture profile of paper was developed. The results show that during paper drying there exist significant gradients in z-directional moisture with profiles showing differences in moisture content of up to 25- 35% across the thickness of the sheet, depending on the drying conditions. Similar magnitude moisture content differentials are observed in both measurements and numerical simulations