4- (Transient heat conduction) Stainless-steel ball bearings (k = 22.2 W/m K, a = 4.85 x 10-6 m 2 /s) which have uniformly been heated to 850°C are hardened by quenching them in an oil bath that is maintained at 40°C. The ball diameter is 20 mm, and the convection coefficient associated with the oil bath is 600 W/m2 K. (a) If quenching is to occur until the surface temperature of the balls reaches 100°C, how long must the balls be kept in the Oil? (b) If 10000 balls are to be quenched per hour, what is the rate at which energy must be removed by the oil-bath cooling system in order to maintain its temperature at 40°C?

4- (Transient heat conduction) Stainless-steel ball bearings (k = 22.2 W/m K, a = 4.85 x 10-6 m 2 /s) which have uniformly been heated to 850°C are hardened by quenching them in an oil bath that is maintained at 40°C. The ball diameter is 20 mm, and the convection coefficient associated with the oil bath is 600 W/m2 K. (a) If quenching is to occur until the surface temperature of the balls reaches 100°C, how long must the balls be kept in the Oil? (b) If 10000 balls are to be quenched per hour, what is the rate at which energy must be removed by the oil-bath cooling system in order to maintain its temperature at 40°C?

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.10P: 3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the...

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