Modeling of flash evaporation I: Formulation of the mathematical model

Impulse drying is a new and efficient method of drying paper that has suffered from a significant weakness, known as delamination; this occurs when the paper is literally blown apart by pressure built up within the pores of the paper during the drying process. Efforts have been made to prevent this phenomenon from occurring by modifying the physical characteristics of the paper sheet and of the press roll. However, only a small amount of work has been done to understand the cause of delamination: the flash evaporation of water within the paper pores. t of an effort to better understand the flash evaporation process occurring during the impulse drying of paper, a model is developed to predict the internal expansion of a sheet of paper. The model is based on established physical and thermodynamical laws and leads to a highly coupled nonlinear system of ODEs for the height, pressure, and water content associated with the pore system internal to the sheet.