Modélisation du séchage en continu d'une nappe de fibres sur un tambour métallique chauffé par induction électrique

• Main Author: Pérez, Sergio A
• Other Authors: Thérien, Normand
• Language: French
• Published: Université de Sherbrooke 2000
• Online Access: http://savoirs.usherbrooke.ca/handle/11143/1720

A model was developed that predicted the evolution of the humidity and the temperature of a thin web of fibrous material during drying on the surface of a metal cylinder heated by electric induction. It also gave the temperature of the cylinder surface as a function of position. The established mass and energy balances and the concept of substantial derivatives were used to relate the state variables as a function of both time and position. The model explicitly considered heat conduction, convection and radiation as well as energy transfer caused by the evaporation of the water. Variations in the humidity of the web arriving at the cylinder were also considered. The model predicted the process responses to perturbations in the manipulated variables, these being the rotational speed of the cylinder, the electric power fed to the system, as well as the area of the web in contact with the cylinder surface. Several experiments carried out using the pilot scale dryer allowed characterization of the responses of the drying process (cylinder temperature, web humidity and temperature) to different combinations of conditions of the manipulated process variables and the initial web humidity. These trials also gave the energetic efficiency of the process. Good characterization of the thermal induction profiles was obtained from complementary measurements of the cylinder temperature during heating. The complete' data established the values of various model parameters and specified the observed tendencies of the system as a function of the manipulated variables. The simulations carried out showed a high degree of correspondence between the model predictions and the experimental results. The model was also used to calculate how modifications in the design of the prototype equipment influenced the energetic efficiency.