During the cooling and hardening phase of its manufacturing process, a glass bead with a diameter of 0.5mm is droed from

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During The Cooling And Hardening Phase Of Its Manufacturing Process A Glass Bead With A Diameter Of 0 5mm Is Droed From 1 (120.39 KiB) Viewed 38 times

During the cooling and hardening phase of its manufacturing process, a glass bead with a diameter of 0.5mm is droed from a height of 10m. The bead falls through still air of temerature 20 C. The properties of the bead material are the same as those listed for window glass in Appendix B: (for window glass) p = 2800kg/m³, cp = 0.80kJ/kg · K, k = 0.81W/mK, a = .0034cm²/s . a) Calculate the "terminal" velocity of the free-falling bead; the velocity when its weight is balanced by the air drag force. Also calculate the approximate time that's needed by the bead to achiee this velocity and show that the bead travels most of the 10m height at terminal velocity. b) Calculate the average heat transfer coefficient between the bead surface and the surrounding air, when the bead travels at terminal velocity and when its surface temperature is T=500 C. Treat the bead as a lumped capacitance and estimate its temperature at the end of the 10m fall. Assume its initial temperature was T=500 C.