Experimental investigation of cooling with multiple air jets on auto glass tempering

Abstract

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 (Num) 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.