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 2, Problem 2.38P
The addition of aluminum fins has been suggested to increase the rate of heat dissipation from one side ofan electronic device 1 m wide and 1 m tall. The fins are to be rectangular in cross section, 2.5 cm long and 0.25 cm thick, as shown in the figure. There are to be 100 fins per meter. The convection heat transfer coefficient, both for the wall and the fins, is estimated to be
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The addition of aluminum fins has been suggested to
increase the rate of heat dissipation from one side of an
electronic device 1 m wide and 1 m tall. The fins are to be
rectangular in cross section, 2.5 cm long and 0.25 cm thick,
as shown in the figure. There are to be 100 fins per meter.
The convection heat transfer coefficient, both for the wall
and the fins, is estimated to be 35 W/m2 K. With this infor-
mation determine the percent increase in the rate of heat
transfer of the finned wall compared to the bare wall.
Fin
100 fins
1 m
Insulation
1= 0.25 cm
2.5 cm
A hot surface at 100 °C is to be cooled by attaching 3-cm-long, 0.25-cm-diameter
aluminum pin fins to it, with a center-to-center distance of 0.6 cm, as shown in Fig. 2.
The temperature of the surrounding medium is 30 °C, and the heat transfer coefficient
on the surfaces is 35 W/m2 K. Determine:
the rate of heat transfer from the surface for a 10-cm x 10-cm section of plate,
the overall effectiveness of the fins.
i
ii
3 cm
0.6 cm
0.25 cm
Fig. 2
The addition of aluminum fins has been suggested to increase the rate of heat dissipation from
one sıde of an electronic device 1 m wide and 1 m tall. The fins are to be rectangular in cross section, 2.5
cm long and 0.25 cm thick. There are to be 100 fins per meter. The convective heat transfer coefficient,
both for the wall and the fins, is estimated at 35 W/m?K. With this information, determine the percent
increase in the rate of heat transfer of the finned wall compared to the bare wall. (Note: 1. Take the base
and the surrounding temperatures are 200°C and 20°C. 2. Assume convection heat transfer at the fin tip)
t = 2.5 mm
- 2.5 cm-
Chapter 2 Solutions
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
Ch. 2 - A plane wall, 7.5 cm thick, generates heat...Ch. 2 -
2.2 A small dam, which is idealized by a large...Ch. 2 - 2.3 The shield of a nuclear reactor is idealized...Ch. 2 - A plane wall 15 cm thick has a thermal...Ch. 2 - 2.5 Derive an expression for the temperature...Ch. 2 - A plane wall of thickness 2L has internal heat...Ch. 2 - 2.7 A very thin silicon chip is bonded to a 6-mm...Ch. 2 - 2.9 In a large chemical factory, hot gases at 2273...Ch. 2 - 2.14 Calculate the rate of heat loss per foot and...Ch. 2 - 2.15 Suppose that a pipe carrying a hot fluid with...
Ch. 2 - Prob. 2.16PCh. 2 - Estimate the rate of heat loss per unit length...Ch. 2 - The rate of heat flow per unit length q/L through...Ch. 2 - A 2.5-cm-OD, 2-cm-ID copper pipe carries liquid...Ch. 2 - A cylindrical liquid oxygen (LOX) tank has a...Ch. 2 - Show that the rate of heat conduction per unit...Ch. 2 - Derive an expression for the temperature...Ch. 2 - Heat is generated uniformly in the fuel rod of a...Ch. 2 - 2.29 In a cylindrical fuel rod of a nuclear...Ch. 2 - 2.30 An electrical heater capable of generating...Ch. 2 - A hollow sphere with inner and outer radii of R1...Ch. 2 - 2.34 Show that the temperature distribution in a...Ch. 2 -
2.38 The addition of aluminum fins has been...Ch. 2 - The tip of a soldering iron consists of a 0.6-cm-...Ch. 2 - One end of a 0.3-m-long steel rod is connected to...Ch. 2 - Both ends of a 0.6-cm copper U-shaped rod are...Ch. 2 - 2.42 A circumferential fin of rectangular cross...Ch. 2 - 2.43 A turbine blade 6.3 cm long, with...Ch. 2 - 2.44 To determine the thermal conductivity of a...Ch. 2 - 2.45 Heat is transferred from water to air through...Ch. 2 - 2.46 The wall of a liquid-to-gas heat exchanger...Ch. 2 - Prob. 2.47PCh. 2 - The handle of a ladle used for pouring molten lead...Ch. 2 - 2.50 Compare the rate of heat flow from the bottom...Ch. 2 - 2.51 Determine by means of a flux plot the...Ch. 2 - Prob. 2.52PCh. 2 - Determine the rate of heat transfer per meter...Ch. 2 - Prob. 2.54PCh. 2 - 2.55 A long, 1-cm-diameter electric copper cable...Ch. 2 - Prob. 2.56PCh. 2 - Prob. 2.57PCh. 2 - Prob. 2.58P
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