Numerical investigation of an inertization system for a radiative coil coating oven

In this work the inertization of a radiative curing oven for coil coating is numerically investigated. Inertization chambers (IC) — comprised by a confined impinging slot jet and an exhaust slot — are applied at the curing oven openings to prevent external air from entering and toxic solvents from exiting the oven, avoiding simultaneously the contamination of the external surroundings and the development of explosive conditions within the oven. The influence of the main IC operating parameters — extracted-to-injected mass flow rate ratio (Ψ), coil plate-to-jet velocity ratio, injection Reynolds number, and oven pressure — on the safety of the sealing process is investigated considering the validated k-kl-ω transition RANS model. To guarantee safety conditions regarding the IC placed at the metal strip entrance, the corresponding range for Ψ was found to be between 0.8 and 1.6 considering oven pressures ranging from −20 to 20 Pa. For the IC placed at the metal strip exit and considering high coil velocities, safety conditions can only be observed with negative oven pressures. Overall, this procedure found a Ψ range between 0.8 and 1.2 that complies with the restrictive safety criteria for a realistic oven operation with typical coil velocities and oven pressures ranging from −20 to 10 Pa.