Computational analysis of spray cooling heat transfer and Influential factors during glass tempering

Abstract

The spray cooling and tempering technology has a series of advantages, such as improving the tempering quality and reducing energy consumption. In order to optimize the tempering technological parameters, it is necessary to accurately control the thermal history and temperature distribution of a hot glass surface during spray cooling. However, measuring the inner temperature of tempered glass proved challenging. The Euler-Lagrangian approach was utilized for simulating the process of spray cooling the glass surface. To validate the accuracy of model predictions, experimental studies were conducted on the tempering of glass by a single nozzle. The numerical outcomes exhibit strong correspondence with the experimental findings. Building upon the foundation, the study analyzed the heat transfer mechanisms in different states including film boiling, nucleate boiling, and forced convection. Subsequently, the effects of spray distance, spray loading fraction, spray pressure, and final cooling temperature on the heat transfer rate and temperature homogeneity were discussed. The results revealed that reducing the spray distance, increasing the spray loading fraction and spray pressure can improve the cooling rate and reduce energy consumption, but it aggravated the uneven distribution of temperature over the glass surface. Moderately increasing the final cooling temperature had little effect on the tempering quality of glass, but it significantly reduced the energy consumption for spray cooling. Within the experimental range, the optimal final cooling temperature was 573.15 K.