Investigations of the drying process of a water based paint film for automotive applications

In a cooperative research project funded by the German BMBF the drying process in the automotive industry has been investigated. More precisely, it was the aim of the project to develop a simulation program that in its final stage allows the calculation of the heat-up process of a fully painted car body, including heat and mass transfer in the thin, water based paint film. The investigations focused on the joint base coat and clear coat drying process used in the automotive industry.A physical model was developed that treats mass and heat transfer of a ternary mixture applied as a thin film on a substrate. This model was added to the commercial CFD-Solver ANSYS-FLUENT and successfully compared with experimental data in practical conditions. The estimation of paint failures, i.e. pinholes that might occur due to unfavourable drying, which is based upon an empirical model applying a design-of-experiments scheme, was also added to the CFD-Solver.