Optical and thermal simulations for infrared powder coating processes

Infrared heating powered by renewable energy sources is a promising alternative to replace fossil fuels in the curing process for industrial powder coatings. Infrared lamps illuminating the sample inside a reflective oven chamber can be individually regulated to generate a homogeneous irradiance distribution on the sample surface, thus allowing to significantly reduce pre-heating and dwell times. As a first step for the layout of an industrial IR-curing line process it is required to identify the crucial performance parameters and understand their interaction with varying shapes and coatings of a part. A better understanding of the process parameters and their influence on the powder curing will allow to apply this technique to complex part geometries in contrast to simple planar surfaces. To achieve this, optical simulations of the irradiance surface distribution in a prototype IR-furnace were performed for different illumination setups. In this paper we focus on the influence of heating-, stabilisation- and cool-off times on the temperature distribution at the sample surface. The irradiance distribution for each sample surface and illumination setup was simulated. Each irradiance distribution was in turn used as an input for transient thermal simulations that model the heating, stabilisation, and cooling phases. The simulated temperature distributions were compared to the temperatures measured via thermal imaging of the corresponding test in the IR-oven. For proof of concept, the parameters of the optical (BSDF) and thermal simulation model (thermal constraints) were adjusted to fit the measured temperature distribution in the IR-furnace prototype system.