Simulation and modelling approach for bubblers effect into molten glass tank

•Air bubblers enhance heat transfer efficiency and product quality into molten glass tank.•Eulerian CFD multiphase model for high temperature viscous liquids determine bubble diameter and velocity.•Single-phase model approximates the multiphase problem.•Variable height of bubblers investigated using a real industrial glass tank. The usage of air bubblers plays an important role in the glass-making industrial process because it enhances the global heat transfer efficiency and especially the uniformity and quality of the finished products. However, glass manufacturers rely on field practice to run their plants, due to the extreme difficulty of conducting experimental investigations in melting tanks. CFD analysis represents a powerful tool to optimize operating parameters and positioning of bubblers and other components, not only in existing plants, but also in the design of new furnaces. In the present paper, the behaviour of bubble columns in highly viscous liquids at high temperature was analysed using the Eulerian multiphase model. The macroscopic effect of the column on the surrounding fluid was translated in a locally momentum source term that was introduced in the single-phase CFD model developed in this study. This solution approximates the multiphase nature of the problem in a reliable way and it is of fast integration in comprehensive models of furnaces. A clear methodology to determine the diameter of the bubbles and the velocity of the bubble chain in the buoyancy source term calculus are presented and analysed in detail. In addition, a validation process based on the comparison with other theoretical and empirical studies on the subject was carried out in detail: it includes the evaluation of the bubble chains properties and effects by varying the liquid viscosity and the inlet gas flow, that is the real operational parameter in industry. Moreover, the effects of the variable height of the bubblers were investigated using the results of a single-phase model of a real industrial glass tank. The analysis of the obtained results shows that the model and the calculation methodologies followed in this work can be effectively applied in the dimensioning process of industrial glass tanks or to optimize existing plants. [Display omitted]