Introduction to Heat Transfer
6th Edition
ISBN: 9780470501962
Author: Frank P. Incropera, David P. DeWitt, Theodore L. Bergman, Adrienne S. Lavine
Publisher: Wiley, John & Sons, Incorporated
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Chapter 3, Problem 3.27P
(a)
To determine
The sketch of thermal circuit corresponding to steady state.
(b)
To determine
The chip surface temperature.
(c)
To determine
The maximum allowable heat flux and the value of heat flux when
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Problems
within the wall is T(x) = a(L- ) +b where
a = 10°C/m2 and b 30°C, what is the thermal con-
ductivity of the wall? What is the value of the convec-
tion heat transfer coefficient, h?
2.11 Consider steady-state conditions for one-dimensional
conduction in a plane wall having a thermal conductiv-
ity k 50 W/m K and a thickness L = 0.25 m, with no
internal heat generation.
2.
T2
T1
L
Determine the heat flux and the unknown quantity for
each case and sketch the temperature distribution, indi-
cating the direction of the heat flux.
2
Case
TC)
dTldx (K/m)
T2(°C)
1
50
-20
2
-30
- 10
3
70
160
4
40
-80
5
30
200
Q2. Steam pumped through a long-
insulated pipe at a temperature of
T= 500 K and provides a convection
coefficient of h, = 100 W/m?K at the inner
surface of the pipe. The inner and outer
radius of the pipe and insulation material
are r1 = 10, r2 = 12 and r3 = 17 cm,
respectively. The thermal conductivity of
the pipe is 100 W/mK. The insulation
material is glass fiber and its outer surface
is exposed to ambient air at 300 K. If the ambient air provides a convection coefficient of ho = 20
Internal flow
Ambient air
W/m?K, determine the followings:
a. What are the thermal resistance coefficients for convections and conductions
b. What is the heat transfer rate per unit length of the pipe
c. If the pipe is 30 m long, what will be total heat transfer rate from the pipe.
t00 noints)
A steel duct whose internal diameter is 5.0 cm, and external diameter is 7.6 cm and thermal conductivity is: k = 15.0 (W/(m ºC)) is covered with an insulating material whose thickness is 2.0 cm and of thermal conductivity k = 0.2 (W/(m ºC)). A hot gas flows through the interior of the duct at a temperature of 330.0 ºC that generates a heat transfer coefficient by forced convection h=400.0 (W/(m^2 · ºC)). The outer surface of the insulating layer is exposed to air whose temperature is 30.0 ºC with forced convection heat transfer surface h = 60.0 (W/(m^2 · °C)).
As a process engineer and in charge of company operations, you have been asked to:
i. Determine the heat loss experienced by the pipe along 10.0 m.ii. The temperature drops that are generated in the different thermal resistances of the system. That is, on the air side, the duct wall and on the hot gas side.
Chapter 3 Solutions
Introduction to Heat Transfer
Ch. 3 - Consider the plane wall of Figure 3.1, separating...Ch. 3 - A new building to be located in a cold climate is...Ch. 3 - The rear window of an automobile is defogged by...Ch. 3 - The rear window of an automobile is defogged by...Ch. 3 - A dormitory at a large university, built 50 years...Ch. 3 - In a manufacturing process, a transparent film is...Ch. 3 - Prob. 3.7PCh. 3 - A t=10-mm-thick horizontal layer of water has a...Ch. 3 - Prob. 3.9PCh. 3 - The wind chill, which is experienced on a cold,...
Ch. 3 - Prob. 3.11PCh. 3 - A thermopane window consists of two pieces of...Ch. 3 - A house has a composite wall of wood, fiberglass...Ch. 3 - Prob. 3.14PCh. 3 - Prob. 3.15PCh. 3 - Work Problem 3.15 assuming surfaces parallel to...Ch. 3 - Consider the oven of Problem 1.54. 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