Simultaneous convective heat and mass transfer in impingement ink drying

Effective and economical drying of the ink is essential in the printing, packaging and converting industries. In evaporative drying, high heat and mass transfer rates are commonly achieved by means of high velocity impinging air jets. To provide data for dryer designer a programme of research has been implemented to study the heat and mass transfer processes which underlie the drying of thin ink films. The heat transfer situation under impinging air jets is outlined and some experimental results are presented. Optimization of nozzle arrays for impinging air jets is analysed for practical applications. Anon-contact infra-red technique for continuously monitoring the ink drying process is described and drying curves for an ink based on a single solvent (4=Methyl-2-pentanol-MIBC) are presented. Heat and mass transfer theory has been used to predict drying times in the constant rate drying period. These predictions have been compared with experimentally determined drying times. This research has served to confirm the fundamental importance of the drying curve as a basis for dryer design. (C) 1998 Elsevier Science Ltd.