Spray cooling heat transfer during glass tempering process and influencing factors on the quality of tempered glass

Abstract

Compared with traditional physical tempering methods, spray cooling method has a series of advantages, such as smaller energy consumption and better tempering quality. However, this technology has not reached a mature level. Present study experimentally investigated the spray cooling for glass tempering at high water/air mass flow ratios for the first time, which verified the feasibility of the spray cooling method. Based on the Eulerian-Lagrange method, a two-phase flow model was established to simulate the spraying cooling on heated glass surface. Both wall-jet and Lagrangian wall-film models were adopted to realize the conversion of several modes of heat transfer. A good agreement between the simulated and experimental temperature and wall film distributions supported the reliability of the established model. Subsequently, the spray cooling heat transfer was numerically studied, and the effects of spray distance, mist flow rate and glass thickness on the tempering quality and heat transfer performance were discussed. The results showed that a decrease in spray distance and an increase in mist flow rate and glass thickness obviously enhanced the temperature difference and quality of the tempered glass. Within the scope of the experiment, the optimum spray distance and mist flow rate were 272.5 mm and 6.94 × 10−4 kg/s, respectively.