MID-TERM EXAM #1: SOLUTIONS
SPRING 2012
[1]
a)
b)
c)
d)
On the left side, the convective heat transfer coefficient is very large. Hence, this fluid is very
well-mixed, with a temperature profile that is essentially uniform. On the right side, the fluid is
Consider the given onedimensional
temperature profile.
At point A:
A)
qx < 0, thus to the left
B)
qx < 0, thus to the right
C)
qx > 0, thus to the left
D) qx < 0, thus to the right
At point B:
A)
qx < 0
B)
qx = 0
C)
qx > 0
T
perfect
insulator
x=0
x
x=0
x
Somepeopletalkintheirsleep.
Lecturerstalkwhileotherpeoplesleep.
AlbertCamus
Whatwehavetolearntodo,welearnbydoing.
Aristotle
Aproblemisachancetodoyourbest.
DukeEllington
Hewhoisafraidtoaskisashamedoflearning.
Danishproverb
A large container of water is pla
CHE 37800
Suggested Practice Problems
P 2.1
t ~ 760 yrs
P 2.12
t ~ 6.3 hrs
P 2.13*
P 2.19
P 2.20*
_
P 3.7*
P 3.15*
P 3.29
t = 3.6 s
P 3.32
PA, R2
Pvap
kR R
= 1 + 2 2 1
DAB R1
1
where k is the reaction rate constant
P 3.35
P 3.38
P 3.40
P 3.42
P 3.45
K
CHE 37800: Heat and Mass Transfer
Spring 2012
Brief Overview of Heat Transfer by Radiation
(For a more complete discussion, see Chapter 15 in Middleman.)
Introduction
Radiation is the energy emitted by any material object as a consequence of its temperatu
CHE 37800: Heat and Mass Transfer
Spring 2012
Brief Overview of Convective Heat Transfer
(For a more complete discussion, see Chapters 12 and 14 in Middleman.)
Convective heat transfer coefficients depend upon many factors, such as the flow profiles that
CHE 37800: Heat and Mass Transfer
Spring 2012
Course Outline
Heat Transfer by Conduction (Chapter 10)
10.1 Fouriers Law of Heat Conduction
10.2 The Composite Solid (steady-state)
Thermal Circuits (Series-Parallel Composites) (lecture notes)
10.3 Finned He
A Physical Interpretation of the Laplace Equation
2T = 0
Begin by considering a one-dimensional temperature profile, that is temperature is only a
function of x, or T = T ( x ) . Now, Taylor expand this function about some value x in the
+x -direction:
d
Source of Variance
Regression
Error
Total
Degrees of
Freedom
2
2
4
Sum of
Squares
12.744
0.043
12.701
Mean Square
F0
P
6.351
0.0217
292.67
3.41u10-3
Since the P value of the ANOVA test does not exceed the chosen significance level D=0.05, the
regression i
Revised: 03/05/2012-DSC
Chemical Engineering Fundamentals Laboratory
CHE 37800
Diffusive Mass Transfer
Objectives
Analyze the equimolar counterdiffusion between CO2 and N2 initially maintained in separate containers. Calculate the
binary (N2-CO2) diffusio
The Heat Conduction Equation
We have so far restricted our attention to conduction problems in which the temperature
gradient is significant for only one coordinate direction. In many cases, however, it is
necessary to account for heat flow in more than o
MID-TERM EXAM #2: SOLUTIONS
SPRING 2012
[1] Answer a).
s
f
In the problem statement, we are told that at equilibrium c A < c A . Hence, across the interface
between the fluid and the membrane, we should find that the concentration of A drops as we go
from
T3 > T2 > T1
y
Consider the given two-dimensional
temperature profile for an isotropic
material, with various contours of
constant temperature (isotherms).
Which arrow represents the direction
of the heat flux vector?
A
B
A
B
C
D
C
D
T3
T2
T1
x
Consider a