A numerical study on the flow and heat transfer characteristics in a noncontact glass transportation unit

Vertical sputtering systems are key equipment in the manufacture of liquid crystal display (LCD) panels. During the sputtering process for LCD panels, a glass plate is transported between chambers for various processes, such as deposition of chemicals on the surface. The minimization of surface scratches and damage to the glass, the rate of consumption of gas, and the stability of the floating glass-plate are key considerations in the design of a gas pad. To develop new, non-contact systems of transportation for large, thin glass plates, various shapes of the nozzle of a gas pad unit were considered in this study. In the proposed nozzle design, negative pressure was used to suppress undesirable fluctuations of the glass plate. After the nozzle's shape was varied through numerical simulations in two dimensions, we determined the optimal shape, after which three-dimensional analyses were carried out to verify the results from the two-dimensional analyses. The rate of heat transfer from the glass plate, as a result of the gas jet, was also investigated. The average Nusselt number at the glass surface varied from 22.7 to 26.6 depending on the turbulence model, while the value from the correlation for the jet array was 23.5. It was found that the well-established correlation equation of the Nusselt number for the circular jet array can be applied to the cooling of the glass plates.