Glass tempering heat transfer coefficient evaluation and air jets parameter optimization

A design of experiments (DOE) matrix of CFD simulations is used to create a mathematical model able to calculate the heat transfer coefficient for nine circular confined air jets vertically impinging on a flat plate. Typical air jets dimensions and process parameter values used in glass tempering are evaluated. The flat plate temperature is set to the constant value of 640 °C. Two different values of jet diameter (4 mm, 8 mm), of air velocity at nozzle exit (110 m/s, 140 m/s), of jet-to-jet spacing (40 mm, 60 mm), of jet-to-plate distance (40 mm, 60 mm) and of nozzle height (20 mm, 60 mm) are considered. Implemented into a Visual Basic application, the mathematical model found allow the instant evaluation of heat transfer parameters and to optimize air jets parameter configuration.