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4th Thermal and Fluids Engineering Conference

ISSN: 2379-1748

NUMERICAL OPTIMIZATION OF DRYING OF LATEX PAINT FILMS ON SOLID SUBSTRATES

Priyanka Chandna
North Carolina State University, Raleigh, NC 27695, USA

Serguei Zelepouga
USG Corporation, IL 60661, USA

Steven Richmond
USG Corporation, IL 60661, USA

Jeffrey Donelan
USG Corporation, IL 60661, USA

Alexei V. Saveliev
Mechanical Engineering Department, College of Engineering, University of Illinois at Chicago, 842 W.Taylor Str.,M/S 251, Chicago 60607, IL, USA; North Carolina State University, Raleigh, NC 27695, USA

DOI: 10.1615/TFEC2019.fip.027640
pages 861-870


KEY WORDS: numerical modeling, drying, paint, process optimization

Abstract

Rapid development of novel paints and coatings for industrial construction boards imposes special requirements on drying processes used. The major requirements include short drying times, energy efficiency, and quality of the formed coatings. Direct optimization approaches based on intensification of the drying process by increasing temperature, heat fluxes, and convective heat and mass transfer coefficients are not successful and often result in coatings with cracks, bubbles, and variable thickness. Alternative approaches, based on drying at moderate temperatures and heat fluxes result in prohibitively long processing times. In this work, a numerical model describing drying of a latex paint on a solid substrate exposed to infrared and convective heat fluxes is developed and used for process optimization. The one-dimensional model combines heat transfer model predicting the temperature distribution in the solid substrate and paint film model describing drying of a paint film on the substrate surface. The paint film model considers drying of the latex film as a two stage process. The first stage involves evaporation of water from the film surface at a constant rate until a critical concentration of water is reached in the film. The water evaporation results in the recession of a water front referred to as the wet film-air interface. The latex particles in the dry layer pack and partially coalesce resulting in a transition from surface evaporation to diffusion through the drying paint film during the second drying stage. The model, validated by experimental results, are used to understand the underlying physical mechanisms and to optimize the drying process.

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