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 degrees 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. (C) 2009 Published by Elsevier Ltd.