MAE 3314: Heat Transfer
Homework #2 Key Assignment (Due date 9/24/14) Passing Score 70/100
* This is a key assignment. Please do ALL THE PROBLEMS.
* Show your problem solving procedure step by step, or no points will be credited.
1. Consider a steam pipe

The University of Texas at Austin
Spring 2016 / ME 339
Prof. M. Nichole RYLANDER
ZKAN
TA: Alican O
Suggested Problems - Week 5
1. The Weather channel reports that it is a hot, muggy day with an air temperature of 90 F, a 10 mph
breeze out of the southwes

Lecture 17: Free Convection:
Cylinders and Spheres
Chapter 9
Section 9.6.3 through 9.8
Cylinders
The Long Horizontal Cylinder
Boundary Layer Development and Variation of the Local Nusselt Number
for a Heated Cylinder:
The Average Nusselt Number:
Boundar

Lecture 13: External Flow:
Flow over Bluff Objects
(Cylinders, Spheres)
Photograph of flow past a circular cylinder. Visualization is by air bubbles in water.
(From An Album of Fluid Motion by Milton Van Dyke)
Chapter 7
Sections 7.4 through 7.8
Cylinder i

Lecture 15: Internal Flow:
Heat Transfer Correlations
Fully Developed Flow
Laminar Flow in a Circular Tube:
The local Nusselt number is a constant throughout the fully developed
region, but its value depends on the surface thermal condition.
Uniform Sur

Lecture 8: Transient Conduction in a
Semi-Infinite Medium
If the lumped capacitance approximation can not be
made, consideration must be given to spatial, as well
as temporal, variations in temperature during the
transient process
Semi-Infinite Solid
Sem

Lecture 11: Introduction to Convection:
Flow and Thermal Considerations
Chapter Six and Appendix D
Sections 6.1 through 6.8
and D.1 through D.3
TYPES OF PROBLEMS
Forced Convection, External Flow
u , T
qs
u , T
qs
As , Ts
As , Ts
Forced Convection, Intern

Lecture 9: 2D SS Conduction:
Finite-Difference Method
Chapter 4
Sections 4.4 and 4.5
Finite-Difference Method
The Finite-Difference Method
An approximate method for determining temperatures at discrete (nodal) points of the
physical system.
The nodal ne

Exam Details
Only allowed to use hard copy of book
Important Items to Study:
Power point notes (understand concepts and examples)
Quizzes
Selected Homework Problems
Important Topics to Review for Exam
Energy Balances
How to draw control volumes sho

Internal Flow:
General Considerations
Chapter 8
Sections 8.1 through 8.3
Entrance Conditions
Entrance Conditions
Must distinguish between entrance and fully developed regions.
Hydrodynamic Effects: Assume laminar flow with uniform velocity profile at
in

Lecture 16: Free Convection:
Vertical and Horizontal Plates
Chapter 9
Sections 9.1 through 9.6.2, 9.9
General Considerations
General Considerations
Free convection refers to fluid motion induced by buoyancy forces
Buoyancy forces arise due to the combin

The University of Texas at Austin
Spring 2016 / ME 339
Prof. M. Nichole RYLANDER
ZKAN
TA: Alican O
Suggested Problems - Week 6
1. A thick-walled steel pipe (k = 60 W/m.K) carrying hot water is cooled externally by a cross-flow
air stream at a velocity of

PROBLEM 7.17
KNOWN: Wall of a metal building experiences a 10 mph (4.47 m/s) breeze with air temperature of
2
90F (32.2C) and solar insolation of 400 W/m . The length of the wall in the wind direction is 10 m
and the emissivity is 0.93.
FIND: Estimate the

The University of Texas at Austin
Spring 2016 / ME 339
Prof. M. Nichole RYLANDER
ZKAN
TA: Alican O
Suggested Problems - Week 7
1. A counterflow, concentric tube heat exchanger used for engine cooling has been in service for an
extended period of time. Th

Three Problem Types
External Forced Convection
Know how to find local and total heat transfer
Internal Forced Convection
Find q and temperature for all boundary conditions and
geometries
Natural Convection
Know how to calculate q and temperature for

Lecture 18: Heat Exchangers:
LMTD Analysis
Chapter 11
Sections 11.1 through 11.3
Types
Heat Exchanger Types
Heat exchangers are ubiquitous to energy conversion and utilization. They involve
heat exchange between two fluids separated by a solid and encompa

The University of Texas at Austin
Spring 2016 / ME 339
Prof. M. Nichole RYLANDER
ZKAN
TA: Alican O
Suggested Problems - Week 4
1. The heat transfer coefficient for air flowing over a sphere is to be determined by observing the temperaturetime history of

Heat Transfer Quiz 5
Name_Solution_
Consider two-dimensional, transient heat transfer in the region shown. The top surface is exposed to convection while the
left surface experiences a uniform heat flux, qs.
Convection: h, T
Uniform flux
T1
qs
y
T2
x
T3
T

Lecture 22: Heat Exchangers:
The Effectiveness NTU Method
Chapter 11
Sections 11.4 through 11.7
General Considerations
General Considerations
Computational Features/Limitations of the LMTD Method:
The LMTD method may be applied to design problems for
wh

PROBLEM 5.6
KNOWN: The temperature-time history of a pure copper sphere in an air stream.
FIND: The heat transfer coefficient between the sphere and the air stream.
SCHEMATIC:
ASSUMPTIONS: (1) Temperature of sphere is spatially uniform, (2) Negligible rad

Lecture 10: Transient Conduction:
Finite Difference Method
Finite-Difference Method
The Finite-Difference Method
An approximate method for determining temperatures at discrete (nodal) points
of the physical system and at discrete times during the transie

PROBLEM 8.59
KNOWN: Thick-walled pipe of thermal conductivity 60 W/mK passing hot water with ReD = 20,000,
a mean temperature of 80C, and cooled externally by air in cross-flow at 20 m/s and 25C.
FIND: Heat transfer rate per unit pipe length, q .
SCHEMATI