ME 364: Elementary Heat Transfer
Summer 2006
Examination 3
Time: 75 minutes
Total Points: 25
Open Book, Open Notes and Open Homework. No other printed/photocopied material.
1.
(5 points)
Experimental measurements of the convection heat transfer coefficient for a
square bar in cross flow yielded the following values:
(i)
1

h
= 50 W/m
2
K when
V
1
= 20 m/s, and (ii)
2

h
= 40 W/m
2
K when
V
2
= 15 m/s.
Assume that the functional form of the Nusselt number is
(
29
n
m
C
Nu
(Pr)
Re
=


, where
C
,
m
, and
n
are constants.
(a) What will be the convection heat transfer coefficient for a similar bar but with
L
= 1 m when
V
= 15 m/s?
(b) What will be the convection heat transfer flux from a similar bar but with
L
=
1 m when
V
= 30 m/s, if the bar surface average temperature is 50
o
C and the free
stream fluid temperature is 25
o
C?
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View Full Document2.
(12 points)
The roof of a refrigerated truck compartment is of composite construction,
consisting of a layer of foamed urethane insulation (
t
2
= 50 mm,
k
i
= 0.026 W/mK)
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 Summer '08
 Rothamer
 Heat, Heat Transfer, convection heat transfer

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