Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
8th Edition
ISBN: 9781305387102
Author: Kreith, Frank; Manglik, Raj M.
Publisher: Cengage Learning
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Chapter 3, Problem 3.3P
To determine
The quench time needed for the plate to attain 900C and the total amount of heat imparted to the quench bath.
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Quenching is a rapid cooling process by which many metallic alloys are hardened. Brass (a copper alloy: 70 Cu, 30 Zn) plates that are 4 mm thick are quenched in a water bath at a heat treating plant. If a brass plate is initially at 4500C determine the quench time needed for the plate to attain 900C. The water bath temperature is 800C and has an average convective heat transfer coefficient of 45 W/(m2 K), determine how long the plate has to remain in the oven.
3-78E Steam exiting the turbine of a steam power plant at
100°F is to be condensed in a large condenser by cooling water
flowing through copper pipes (k = 223 Btu/h ft. °F) of inner
diameter 0.4 in. and outer diameter 0.6 in. at an average
temperature of 70°F. The heat of vaporization of water at
100°F is 1037 Btu/lbm. The heat transfer coefficients are 1500
Btu/h ft² °F on the steam side and 35 Btu/h ft² °F on the
water side. Determine the length of the tube required to con-
dense steam at a rate of 120 lbm/h. Answer: 1148 ft
Steam, 100°F
120 lbm/h
Liquid water
FIGURE P3-78E
Cooling
water
A long copper cylinder 0.6 m in diameter and initially at a uniform temperature of 38oC is placed in a water
bath at 93oC. Assuming that the heat transfer coefficient between the copper and the water is 1248 W/(m2
* K), calculate the time required to heat the center of the cylinder to 66oC. As a first approximation, neglect
the temperature gradient within the cylinder; then repeat your calculation without this simplifying
assumption and compare your results.
Chapter 3 Solutions
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
Ch. 3 - Consider a flat plate or a plane wall with a...Ch. 3 - 3.2 High-strength steel is required for use in...Ch. 3 - Prob. 3.3PCh. 3 - 3.5 In a ball-bearing production facility, steel...Ch. 3 - A 0.6-cm diameter mild steel rod at 38C is...Ch. 3 - Prob. 3.7PCh. 3 - Prob. 3.8PCh. 3 - 3.9 The heat transfer coefficients for the flow of...Ch. 3 - 3.10 A spherical shell satellite (3-m-OD,...Ch. 3 - Prob. 3.11P
Ch. 3 - Prob. 3.12PCh. 3 - Prob. 3.13PCh. 3 - 3.14 A thin-wall cylindrical vessel (1 m in...Ch. 3 - A thin-wall jacketed tank heated by condensing...Ch. 3 - 3.16 A large, 2.54-cm.-thick copper plate is...Ch. 3 - 3.17 A 1.4-kg aluminum household iron has a 500-W...Ch. 3 -
3.28 A long wooden rod at with a 2.5-cm-OD is...Ch. 3 - A mild-steel cylindrical billet 25 cm in diameter...Ch. 3 - Prob. 3.37PCh. 3 -
3.38 An egg, which for the purposes of this...
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