Mist Cooling for Thermal Tempering of Glass

Abstract

This paper presents a feasibility study of glass tempering using mist cooling. First, transient tests of mist cooling were conducted to investigate the effects of the thermal properties of a cooling surface. To do this, test plates made of silver, nickel, stainless steel (SUS 304), and fused quartz were used. The experimental conditions of mist flow were as follows : the air velocity was Va=20 m/s, the temperature of the water droplets was Tl=21°C, and the volumetric droplet flow rate was D=0.000 3∼0.01 m3/(m2·s). The experimental data show that both the plate temperature corresponding to the minimum heat flux (TM) and the heat transfer coefficients at wall temperature above TM increase as the thermal conductance of the surface material decreases. Second, tempering tests of soda-lime glass plates of 2.95 and 3.90 mm thickness were conducted using mist cooling. The initial temperature of the glass plates was about 690°C. The plates were cooling. The initial temperature of the glass plates was about 690°C°C. The plates were cooled only from one side. The test results indicate that thin and low-cost tempered glass plates can be made by mist cooling without fracture.