SOLUTIONS MANUAL
,Solutions manual to accompany principles of heat transfer, 7th edition
TABLE OF CONTENTS
CHAPTER PAGE
1 1
2 88
3 234
4 311
5 420
6 509
7 601
8 679
9 777
10.....................................................................................................................863
, Chapter 1
PROBLEM 1.1
The outer surface of a 0.2m-thick concrete wall is kept at a temperature
of –5°C, while the inner surface is kept at 20°C. The thermal conductivity
of the concrete is 1.2 W/(m K). Determine the heat loss through a wall 10
m long and 3 m high.
GIVEN
10 m long, 3 m high, and 0.2 m thick concrete wall
Thermal conductivity of the concrete (k) = 1.2 W/(m K)
Temperature of the inner surface (T i )= 20°C
Temperature of the outer surface (T o )= –5°C
FIND
The heat loss through the wall (qk)
ASSUMPTIONS
One dimensional heat flow
The system has reached steady state
SKETCH
SOLUTION
The rate of heat loss through the wall is given by Equation (1.2)
AK
qk = ( T)
L
qk = (10 m)(3m)(1.2 W/(m (20°C – (–5°C))
K))
0.2 m
qk = 4500 W
COMMENTS
Since the inside surface temperature is higher than the outside temperature heat is
1
© 2011 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
, transferred from the inside of the wall to the outside of the wall.
2
© 2011 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
,Solutions manual to accompany principles of heat transfer, 7th edition
TABLE OF CONTENTS
CHAPTER PAGE
1 1
2 88
3 234
4 311
5 420
6 509
7 601
8 679
9 777
10.....................................................................................................................863
, Chapter 1
PROBLEM 1.1
The outer surface of a 0.2m-thick concrete wall is kept at a temperature
of –5°C, while the inner surface is kept at 20°C. The thermal conductivity
of the concrete is 1.2 W/(m K). Determine the heat loss through a wall 10
m long and 3 m high.
GIVEN
10 m long, 3 m high, and 0.2 m thick concrete wall
Thermal conductivity of the concrete (k) = 1.2 W/(m K)
Temperature of the inner surface (T i )= 20°C
Temperature of the outer surface (T o )= –5°C
FIND
The heat loss through the wall (qk)
ASSUMPTIONS
One dimensional heat flow
The system has reached steady state
SKETCH
SOLUTION
The rate of heat loss through the wall is given by Equation (1.2)
AK
qk = ( T)
L
qk = (10 m)(3m)(1.2 W/(m (20°C – (–5°C))
K))
0.2 m
qk = 4500 W
COMMENTS
Since the inside surface temperature is higher than the outside temperature heat is
1
© 2011 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
, transferred from the inside of the wall to the outside of the wall.
2
© 2011 Cengage Learning. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.
