Name _ Spring 2008
ME 3304: Test 1
Open book and 1 review sheet allowed. No other materials permitted.
Instructor: Vick_ Nichole Rylander Chris Rylander Ekkad
Problem 1: 25%
A long wire of radius r1 = 0.25 cm and thermal conductivity kw of 25 W
Final Exam Review
Steady Energy Balance for Convection, Radiation, and Conduction
Transient Energy Balance Lumped Capacitance Method
Parallel and Series Pathways
Fouriers Law
Draw Diagrams with Control Volumes and Plots
Definitions: Re, Nu, Pr, Sc, Le, Sh
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kgg I 7 5) I w
ME 3304 - Test 2 Closed Book, Closed notes
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Only the front side of pages will be graded. If you need additional sheets, place them behind that
individual problem and re-staple.
Shortanswer questions (10 points)
1.
Mass Transfer
Brownian Motion (Conduction)
Concentration, C
(Driving Force)
Diffusion Coefficient, DAB (Material Property)
Mass Flux,
Heat Flux,
C
T
"= D
q" =
x
x
Conservation of mass (steady)
2
C
=0
2
C
= (1 2 )
" =
x
Water in Air (evaporation)
R
Forced Convection
Transport of thermal energy and mass by
bulk movement of fluid.
Creates heat and mass transfer coefficients at
solid boundaries by combination of diffusion
and fluid motion.
Fluid
Solid
h
=
=
; Prandtl, =
Fluid Reynolds, =
Fluid Viscos
Process for Learning Heat Transfer
1. Class notes: I demonstrate, you do yourself at home.
2. Homework: Practice for quizzesuse same format,
15-20 min., closed book and computer. By yourself.
Using a solution negates the process.
3. Quizzes are practice f
Heat Transfer Correlations for a Smooth Flat Plate
Draw Diagram
Properties at Tf = (Ts + T) / 2
Local
Laminar
Const. q"
BC
Nux = 0.332Rex1/2 Pr1/3
Pr 0.6
(7.23)
Nux = 0.453Rex1/2 Pr1/3
Rex
q" or q
Average
Turbulent
Laminar
Const. q"
Const. T
BC
ReL
Mixed
ME 3304 - Test 1
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Only the front side of pages will be graded. Add sheets if needed and place behind the problem
Problem 1 (25 points) A pin n of l-cm diameter and length 5 cm is attached to a heat sink at a
temperature of To = 20C. The
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ME 3304 - Quiz 6
Name k :52 Pledge
A constant temperature smooth at plate has a uid owing parallel over the top surface with a laminar
boundary layer starting at X 0 as described by
Local Nux = O. 332Re5Pr1/3
ME 3304 - Quiz 9
Name L4 L3: % Pledge
A tubein tube heat exchanger is to be specied for heating a process uid from 30C with 90 kW of heat
transfer from the hot uid, which enters with an inlet temperature of 90C. The tube separating the two
uids has an ins
\ ME 3304 - Quiz7
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A 6m long pipe is wrapped with a heating tape that supplies heat ux that varies along the pipe length
according to the equation q" = ax + b, where the value of a = 300 W/m3 and b = 600 W/mz. The water
mass ow rate is
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.1\ ME 3304 - Quiz 8
Name L4 1: 1 Pledge
Wate1 at a tempe1atu1e of 17C and ave1 age velocity of 3.0 m/s ente1s a 1ectangula1 duct that IS 21: 3.0
cm wide, b - 1.0 cm high The walls of the duct ale smooth and held at a constant 67C The b
ME 3304 - Quiz 4
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Consider a portion of a rod of diameter d = 1 cm which is conducting electrical current that generates a
uniform volumetric heat generation of q = 105 W/m3. The rod is surrounded by air at a temperature of
30C with a hea
ME 3304 - Quiz 12
Name (A Ei/ Pledge
A at heat ux sensor 2(1) with a surface a1_ea of 0.3 cm2 coveis the end of a cavity (2) with a total
surface a1ea of l 5 cm2. Both surfaces a1e gray with an emissivity of 0.7. The senso1 is maintained at a
temperature
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ME 3304 ~ Quiz HT 3
Pledge
A cylindrical container of diameter 3 cm and length of 5 cm is lled with a material that is uniformly
dissipating electrical power with a q = 106 W/m3. The cylinder is perfectly insulated on the all
surfaces except fo
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1
ME 3304 - Quiz 10
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E
1 Hot exhaust gases at 200C a1e to be used to heat wat
61 from 30C 1n a CIOSSOW heat exchange1 The ove1all
11eat t1ansfe1 coefcient when clean 1s 200 W/m2
K. You are to specify a desi
.3 - ME 3304 Quiz 11
Name VNE if, r ' Pledge
Consider two black squares 0.2 m On each side that are facing each other. The View factor from the
surface of one to the other is 0.40. The surrounding room (also black) is at a temperature of 300 K. If the
rst
ff? 3?
d
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ME 3304 - Quiz 5
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Results of experimental heat ux measurements at the stagnation point of a cylinder are shown below
for a diameter of 10 cm. The characteristic length of a cylinder is the diameter. Remember algebra
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ME 3304 - Quiz 1
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An electric heater is mounted on the top surface of a plate with a power of P6; 200 W. The area of
the heater and the plate is A = 0.1 m2. Assume steady-state conditions and one~dimensional
transfer
ME 3304 - Quiz 2
NameEL Pledge
A tapered shaft is shown below. The sides are perfectly insulated (adiabatic) and the ends are at
temperatures T; and T2, respectively. The shaft has a thermal conductivity of k. The cross-sectional
area of the shaft is expr