EML 4147C
Test 1, Open book, closed notes
Name ____________________
Page 1 of 6
Circle the closest answer.
1a)
What is the thermal resistance due to the stainless steel tube?
a)
8.85 x 10
4
W/K
b)
0.0017 K/W
c)
8.351 x 10
4
K/W
d)
1197.4 W/K
d)
0
1b)
What is the thermal resistance due to the fouling on the outside of the tube?
a)
0.0037 K/W
b)
272.3 K/W
c)
6.46 x 10
8
K/W
d)
0.141 K/Wm
e)
0.159 K/Wm
1c)
What is the coldside overall heat transfer coefficient
U
c
?
a)
230 W/mK
b)
215 m
2
K/W
c)
0.0689 W/m
2
K
d)
14.51 W/m
2
K
e)
225 W/m
2
K
2a)
What is the log mean temperature difference
Δ
T
lm
?
a)
91.72 °C
b)
93.18 °C
c)
98.65 °C
d)
105.83 °C
e)
112.27 °C
2b)
What is the length of the heat exchanger?
a)
0.921 m
b)
0.968 m
c)
1.23 m
d)
1.31 m
e)
1.39 m
2c)
After 3 years of operation, performance is degraded by fouling on the water side of the exchanger, and the water outlet temperature is only 65 C
for the same fluid flow rates and inlet temperatures.
What is the new heat transfer rate
q
?
a)
2010 W
b)
2250 W
c)
2430 W
d)
2660 W
e)
2775 W
2d)
What is the new outlet temperature of the oil?
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 Spring '11
 ABBITT
 Heat Transfer, heat transfer coefficient, Log mean temperature difference, overall heat transfer

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