ME 410
Fall 2007
Homework 3 Due: September 11, 2007
1. Consider a large plane wall of thickness L = 0.06 m. The wall surface at x = 0 is insulated while the surface at x = L is maintained at a temperature of 25C. The thermal conductivity of the wal
ME 410
Spring 2008
Homework 9 Due: March 13, 2008
1. Identify the classification of the following heat transfer (convective flow) problems. Note that there may be other modes of heat transfer present (e.g. radiation or conduction), but ignore those
ME 410
Spring 2008
Homework 9 Due: March 13, 2008
1. Identify the classification of the following heat transfer (convective flow) problems. Note that there may be other modes of heat transfer present (e.g. radiation or conduction), but ignore those
ME 410 Name
Spring 2008
Exam 2
Exam is open notes, open book. Problems have indicated point value. Problem 1 (30 pts) Often a watermelon is cut in half and put into the freezer to cool it quickly. If it is left in the freezer to long, a frozen laye
ME 410
Spring 2008
Homework 10 Due: March 27, 2008
1. Air at 4E-4 kg/s and 27C enters a triangular duct that is 20 mm on a side and 2 m long. The duct surface is maintained at 120C. Determine the air outlet temperature.
2. Determine the surface te
ME 410 Name
Spring 2008
Exam 3
Exam is open notes, open book. Problems have indicated point value. Problem 1 (50 pts) The sides of an electronics package are rectangular aluminum plates 70 cm wide and 40 cm high and act as a heat sink for the conte
ME 410
Spring 2008
Homework 10 Due: March 27, 2008
1. Air at 4E-4 kg/s and 27C enters a triangular duct that is 20 mm on a side and 2 m long. The duct surface is maintained at 120C. Determine the air outlet temperature. Ts = 120C
Determine Air out
Chapter 15 Steady Heat Conduction Thermal Contact Resistance 3-39C The resistance that an interface offers to heat transfer per unit interface area is called thermal contact resistance, Rc . The inverse of thermal contact resistance is called the the
ME 410 Name
Spring 2008
Exam 1
Exam is open notes, open book. Problems have indicated point value. Problem 1 (40 pts) Consider the base plate of a 1200 W household iron that has a thickness of L= 0.5 cm, base area of A = 300 cm2, and a thermal cond
ME 410
Spring 2008
Homework 1 Due: January 10, 2008
1. Describe five everyday processes that involve heat transfer. State what modes are acting in the process. Take one of the processes from Problem #1 that interests you and provide a detailed desc
Radiation Reading Chapters 12-13 Incropera and DeWitt, 5th Edition.
The text takes a much more theoretical (and consequently mathematical) approach to radiation and radiation properties then I have presented in class. Please note, when I suggest tha
Convection Reading Chapters 6-9 Incropera and DeWitt, 5th Edition.
Chapter 6 has been covered conceptually. background are 6.1, 6.2.1, 6.2.2, 6.3, 6.4.
Recommend Sections for
Chapter 7- Section 7.2.1 does some background on solving momentum and en
ME 410
Spring 2008
Homework 13 Due: April 22, 2008
Determine the temperature of a 200 W cylindrical heating element of diameter 2 cm by length 1 m suspended inside a parallelepiped oven of dimensions 1m by 1m by 1m. The oven walls are at 500 K and
PROBLEM 12.48
KNOWN: Large body of nonluminous gas at 1200 K has emission bands between 2.5 3.5 m and
between 5 8 m with effective emissivities of 0.8 and 0.6, respectively.
FIND: Emissive power of the gas.
SCHEMATIC:
ASSUMPTIONS: (1) Gas radiates only in
Solution Methodology for One-Dimensional Transient Conduction
There are several different methods for solving 1-D, transient conduction problems that begin as a uniform temperature and are suddenly exposed to convection. Lumped Capacitance Method (LC
Flow Chart for 1-D Transient Heat Conduction Solutions
Bi = hLc 0 .1 k V Lc = A
Yes
Lumped Capacitance
Fo =
t
Lc
2
Lc =
V A
Fo=
t
L2
0.2
One-term approximation
Yes
Bi =
L is the half-plane thickness or radius
hL k
L is the half-plane
Solution Procedure for the SOV Method
1. Assume F (x ) = i f ( x i ) Where: F is the dependent variable x = [x1 x2 x3 . xn] is a vector of independent variables
For example:
2.
( x, Fo) = g ( x )h( Fo)
Substitute product into differential equati
ME 410
Radiation Enclosures for Gray, Opaque surfaces
Summary Each surface in an enclosure must have a radiation equation associated with it. There are three possibilities depending on the thermal boundary condition. Temperature Condition - Ti known
ME 410
1-D Transient Heat Conduction An initially uniform temperature object subjected to convective heat transfer One term approximation for temperature distribution, valid when Fo > 0.2 Plane Wall of width 2L, x* =
x L
:
* ( x * , Fo)=
T ( x *
ME 410
Spring 2008
Homework 7 Due: February 19, 2008
1. 5.37 from text 2. 5.53 from text 3. 5.78 from text
ME 410
Spring 2008
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Spring 2008
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Spring 2008
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Spring 2008
ME 410
Spring 2008
Homework 10 Due: March 20, 2008
1. Consider a rectangular fin that is used to cool a motorcycle engine. The fin is 0.15 m long and at a temperature of 250C, while the motorcycle is moving at 80 km/h in air at 27C. The air may be
ME 410
Spring 2008
Homework 13 Due: April 22, 2008
Determine the temperature of a 200 W cylindrical heating element of diameter 2 cm by length 1 m suspended inside a parallelepiped oven of dimensions 1m by 1m by 1m. The oven walls are at 500 K and
ME 410
Spring 2008
Suggested Review Problems 5 Edition of Incropera and DeWitt
th
Topics Fundamental conduction, convection and radiation equations Heat conduction one-dimensional problems using the energy equation thermal resistance network solve
ME 410
Spring 2008
Homework 5 Due: January 31, 2008
1. 3-127 from text 2. 3.144 from text 3. 3.149 from text
ME 410
Spring 2008
ME 410
Spring 2008
ME 410
Spring 2008
ME 410
Spring 2008
Homework 2 Due: January 15, 2008
From 5th edition of Incropera and DeWitt, 1.7, 1.13, 1.18,1.30
ME 410
Spring 2008
ME 410
Spring 2008
ME 410
Spring 2008
ME 410
Spring 2008
ME 410
Spring 2008
Homework 12 Due: April 15, 2008
1. Determine the radiation heat transfer for a red-hot poker at 1200 K in the following wavelength ranges a.) the black body emissive power in the infrared region of the spectrum, 0.76 m < < 100 m
Chapter1 Example 2 (Example 1.2 in the book, p.10)
An uninsulated steam pipe passes through a room in which the air and walls are at 25C. The outside
diameter of the pipe is 70mm, and its surface temperature and emissivity are 200C and 0.8, respectively.
Chapter2 - Example 1
A short cylindrical metal billet of radius R and height h is heated
in an oven to a temperature of 600F throughout and is then
taken out of the oven and allowed to cool in ambient air at
Tf = 65F by convection and radiation. Assuming
Chapter1 Example 1
The roof of an electrically heated home is 6m long, 8m wide, and 0.25m thick, and is made of a flat layer
of concrete whose thermal conductivity is 0.8 W/m-K. The temperature of the inner and the outer
surfaces of the roof one night are
Chapter1 Example 3
A 15cm-diameter aluminum ball is to be heated from 80 oC to an average temperature of 200 oC. Taking
the average density and specific heat of aluminum in this temperature range to be 2700kg/m 3 and
0.90kJ/kg-K, respectively, determine t
Chapter2 - Example 2 (Example 2.3 in the book)
The temperature distribution across a wall 1m thick at a certain
instant of time is given as T ( x) a bx cx 2
where T is in C and x in m, while a = 900 C, b = -300 C/m, and
c = -50 C/m2. A uniform heat genera