Department of Chemical Engineering
University of California, Santa Barbara
ChE120B
Heat Transfer
Winter 2010
Homework:
Out  Wednesday,
March 3, 2010
Due  Friday, March 12 2010
1.The following data is available for heat transfer to corn syrup solutions flowing through a
heated
0.75 inch inside diameter pipe.
In class, we derived the approximate relationship using
the friction factor and the Reynolds analogy to get St =f/2. St is the Stanton number = Nu/(Re
Pr).
How well does this equation fit the data presented below?
Solution 1: Pr = 590
Solution 2: Pr = 93
Re
Nu
Re
Pr
2580
80
3840
88
3750
135
5450
125
5000
200
7340
181
6000
235
9419
224
7200
280
11210
267
17130
368
21120
441
2.
A correlation commonly recommended for predicting the heat transfer to a fluid in turbulent
flow through a pipe is the DittusBoelter equation:
Nu = 0.023 Re
0.8
Pr
b
in which b = 0.4 for heating the fluid and b= 0.3 for cooling the fluid.
Does either of these
correlations fit the data above better than the simple relationship given in Problem 1?
What is
your newfound experience on the relative accuracy of Nusselt number correlations?
3.
For flow through a pipe of length L and diameter, D, with an isothermal wall, we can write
the temperature of the fluid as follows
2
1
4
exp
w
w
T
T
StL
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 Winter '10
 Zasadinski
 Chemical Engineering, Heat, Heat Transfer, pipe

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