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    THE EFFECT OF DIFFERENT COOLING UNIT CONFIGURATIONS AND COOLING TEMPERATURES ON GLASS TEMPERING QUALITY
    (Begell House Inc, 2016) Akcay, Mehmet; Yazici, Hilmi; Golcu, Mustafa; Sekmen, Yakup
    In this study, an auto glass tempering process was conducted in different cooling unit configurations and cooling temperatures, and the changes in the sudden cooling time and the number of broken glass particles of the tempered glass plates were examined. Six-millimeter-thick glass plates were heated up to T-h = 680 degrees C and then suddenly cooled at four different cooling temperatures (T-c = 70, 250, 300, and 400 degrees C). In the sudden cooling process, the rate of the distance between nozzle axes to nozzle diameter (S/D) was taken as 4 <= S/D <= 8, the rate of the distance to the glass surface to nozzle diameter (H/D) was taken as 2 <= H/D <= 8, and the Reynolds number was kept constant at Re = 20,000. According to the results revealed in the study, as the S/D and H/D rates increased, the cooling time increased and the number of particles decreased. It was found that the sudden cooling time and the number of particles changed in inverse proportion to the cooling temperature. When the cooling temperature was decreased from 250 degrees C to 70 degrees C for each cooling unit configuration (S/D = 4, 6, and 8), there was a high increase in the cooling time, whereas the increase in the number of particles was quite small.
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    THE EFFECT OF HEATING AND COOLING TEMPERATURES ON RAPID COOLING TIME AND PARTICLE NUMBER IN AUTO GLASS TEMPERING PROCESS
    (Gazi Univ, Fac Engineering Architecture, 2014) Akcay, Mehmet; Sekmen, Yakup; Golcu, Mustafa
    In terms of tempering quality, controlling and applying of heating and rapid cooling processes are very important in the glass tempering process. In this study, auto glass tempering process was implemented in the prototype glass tempering unit which was designed specifically, exchange of cooling time and particle number was investigated according to heating and cooling temperatures. Without going out of standards, it was aimed to determine the tempering conditions which are needed to keep the energy consumption at minimum in glass tempering process. Glasses that were heated to three different average surface temperatures (T-h=620, 650 and 680 degrees C) were rapidly cooled to four different average surface temperatures (T-c=70, 250, 300 and 400 degrees C). The distance between the nozzle and the glass surface is H, the distance between the nozzle axes is S. It was considered 2 <= H/D <= 8, S/D=4 and Reynolds number Re=20000. According to the study; while higher heating temperature of the glass resulted in higher particle number, higher cooling temperature resulted in lower particle number. Although there are quite high differences between the sudden cooling times for cooling temperatures T-c=70, 250 and 300 degrees C, particle numbers are close to each other.
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    EXPERIMENTAL INVESTIGATION OF COOLING WITH MULTIPLE AIR JETS ON AUTO GLASS TEMPERING
    (Gazi Univ, Fac Engineering Architecture, 2012) Golcu, Mustafa; Yazici, Hilmi; Akcay, Mehmet; Koseoglu, Mehmet Fevzi; Sekmen, Yakup
    Impinging air jets due to their high heat and mass transfer capacity are widely used for heating, cooling and drying applications in nowadays industry. This study aims to investigate auto glass tempering project. Heat transfer characteristics of heated glass plates during their cooling with mutually placed circular air jets have been experimentally investigated. 4 mm thick glass samples were used in the experiments. Cooling process has been performed with 16 mutually placed nozzles of 8 mm in diameter and 80 mm in length in staggered arrangement. Nozzles were made of seamless aluminum pipes. Experiments have been conducted for dimensionless jet to plate distances (H/D) between 1 and 10, and S/D ratios which represents dimensionless distance between nozzle axis, for 2 <= S/D <= 10. Reynolds number has been fixed at 30000 for all experiments. According to the results the highest average Nusselt number (Nu(m)) has been achieved for S/D=2 and H/D=4 with a value 123.3 and the lowest average Nusselt number was obtained for S/D= 10 and H/D= 10 with a value 58.6.