PERALTA Juan Manuel
congresos y reuniones científicas
Mathematical modeling of a dip coating process using a generalized Newtonian fluid
PERALTA, J. M.; MEZA, B. E.; ZORRILLA, S. E.
Congreso; Ift 2014 - Annual Meeting and Food Expo; 2014
Institute of Food Technologists
Coating is an industrial process used by food industry to produce a continuous or discontinuous film of non-volatile material on a solid substrate. Dip coating consists in the immersion of the substrate into a reservoir containing the film-forming fluid for a certain period of time that ensures the wetting and then, the withdrawing of the substrate from the bath. Afterward, the fluid drainage by gravity completes the film formation. The objective of this work was to develop and validate a mathematical model of the fluid dynamic variables in a dip coating process, considering that the film-forming fluid behaves as a generalized Newtonian fluid. An analytical and simple mathematical model that relates the main parameters in a dip coating process using a generalized Herschel-Bulkley model was proposed. This model was obtained based upon rigorous mass and momentum balances applied to a monophasic and non-evaporative system, where the main forces are viscous and gravitational. The phenomena occur far away from the meniscus that is formed at the surface of the fluid-forming reservoir. A validation process was carried out using experimental data of average film thickness of different film-forming fluids obtained from literature (milk chocolate, deep-fat frying batters, sugar syrup, glycerine-water, mineral oil, and carbopol solutions). Based on the low errors obtained (RMSE less or equal to 0.1 mm), predictions were considered satisfactory. The parameters that can be estimated are: velocity profile, average velocity, flow rate, local thickness, and average thickness of the coating film. Finally, the sufficient conditions for the model were obtained. The developed and validated model is considered a very attractive tool to be used directly by industry due to its simplicity and precision based on their theoretical nature, the easy mathematical background, and the incorporation of a generalized rheological model.