The Hong Kong University of Science and Technology
MECH 3310

Spring 2016
1D Steady Conduction w/o Eg:
Thermal Circuit Analogy
S. Yao MECH3310 Lecture 4 Ch 3.13.2 17/02/2016
1
For 1D Steady Conduction w/o Eg ,
Whats the Temp. Distribution in a Plane Wall ?
q x
dx 0
x
T
Fouriers Law: q x kA
x
1st Law: Ein Eout
qx
qx+dx
Why l
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Fall 2016
S.Yao
Handout 9
Homework Assignment 8
Due: 22/11/2016
1. A 1mdiameter spherical cavity is maintained at a uniform temperature of 800 K. A 5 mmdiameter hole is drilled. (a) Calculate radiation energy streaming through the hole. (b) What
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Spring 2016
S.Yao
Handout 8
Homework Assignment 7
Due: 15/11/2016
1. A 3mmdiameter and 12mlong electric wire is tightly wrapped with a 1.5mmthick
plastic cover whose thermal conductivity and emissivity are k = 0.20 W/mC and = 0.9.
Electrica
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
RT  3K3 =1 #MK 9 FwgLWIx to
(J 2 M" : Xo #223224.
= (r _ x cm 2 7,
=0H'5W <
e40 *0 '= (0). = ~01:
A21 (P .6 Junk
a : 1  8?8 M <
c. n'
_=2&
1 = 6144 <
e 5 ve M : ft.
m
FA 1 = RA,
:0. zszIoqxc r
:1 xlo w w .M
e ow
Em =
= .9! Ko3ww <
346 g 1*
l
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Fall 2016
S.Yao
Handout 7
Homework Assignment 6
Due: 08/11/2016
1. Water is to be heated from 10 C to 40 C as it flows through a 5cminnerdiameter, 5mlomg tube. The tube is equipped with an electric resistance heater that provides uniform
heat
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Fall 2016
S.Yao
Handout 6
Homework Assignment 5
Due: 28/10/2016
1. The forming section of a plastic plant puts out a continuous sheet of plastic that is 1.2 m
wide and 0.1 cm thick at a velocity of 9 m/min. the temperature of the plastic sheet is
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
1D Steady Conduction w/ Eg
S. Yao MECH3310 Lecture 6 Ch 3.5 20/09/2016
1
For 1D Steady Conduction w/ Eg, thermal circuit does NOT apply, must
solve the heat conduction equation.
Involves a local (volumetric) source of thermal energy due to conversion
f
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Fall 2016
S.Yao
Handout 5
Homework Assignment 4
Due: 04/10/2016
1. An aluminum block is cast with an array of pin fins protruding out of the base of the
aluminum block, which is assumed constant at 70 C. The surrounding air is 20 C, and the
heat
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
Transient Conduction:
Semiinfinite Solid
S. Yao MECH3310 Lecture 9 Ch 5.4, 5.7 29/09/2016
1
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
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
Q2
Assumption: (1) Two plates are regarded as diffuse and grey surface; (2) Room treated as
blackbody; (3) convection is negligible.
Schematic:
Eb =J
3
3
Solution:
View factor calculation:
=Y
= 2. From Fig 13.4, we have F12=F210.42.
For parallel plates,
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Fall 2016
S.Yao
Handout 10
Homework Assignment 9
Due: 29/11/2016
1. A spherical incubator and the egg inside can be modeled as concentric spheres. The
incubator is 18 cm in radius with inc = 0.2, and Tinc = 50 C. The egg has approximate
radius of
The Hong Kong University of Science and Technology
MECH 3310

Spring 2016
Extended Surfaces (Fins)
S. Yao MECH3310 Lecture 7 Ch 3.6 26/02/2016
1
An extended surface (fin) is a solid within which heat transfer by conduction
is assumed to be 1D, while heat is also transferred by convection (and/or
radiation) from the surface in
The Hong Kong University of Science and Technology
MECH 3310

Spring 2016
MECH231 Spring 2016
S.Yao
Handout 4
Homework Assignment 3
Due: 02/03/2016
1. The steadystate temperature distribution in a composite plane wall of three materials (each
has constant thermal conductivity) is shown below.
(a) Compare magnitudes of q2, q3,
The Hong Kong University of Science and Technology
MECH 3310

Spring 2016
MECH3310 Spring 2016
S.Yao
Handout 3
Homework Assignment 2
Due: 24/02/2016
1. Consider a large plane wall of thickness L = 0.3 cm, thermal conductivity k = 2.5 W/mK,
and surface area A = 12 cm2. The left side of the wall at x = 0 is subjected to a net hea
The Hong Kong University of Science and Technology
MECH 3310

Spring 2016
Conduction: Fundamentals
S. Yao MECH3310 Lecture 3 Ch 1.31.4 12/02/2016
1
Fouriers Law
A rate equation that allows determination of the conduction heat flux
from knowledge of the temperature distribution in a medium
Its most general (vector) form for m
The Hong Kong University of Science and Technology
MECH 3310

Spring 2016
Transient Conduction:
Semiinfinite Solid
S. Yao MECH3310 Lecture 9 Ch 5.4, 5.7 04/03/2016
1
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
The Hong Kong University of Science and Technology
MECH 3310

Spring 2016
MECH3310 Spring 2016
S.Yao
Handout 2
Homework Assignment 1
Due: 17/02/2016
1. The heat generated in the circuitry on the surface of a silicon chip (k = 130 W/mK) is
conducted to the ceramic substrate to which it is attached. The chip is 6 mm * 6 mm in siz
The Hong Kong University of Science and Technology
MECH 3310

Spring 2016
MECH3310
Heat Transfer
Shuhuai Yao
Department of Mechanical and Aerospace Engineering
The Hong Kong University of Science and Technology
S. Yao MECH3310 Lecture 1 Ch 1.11.2 03/02/2016
1
Course Information
Instructor:
YAO, Shuhuai (RM2577F, Tel 23587205,
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
Lumped Capacitance Model
S. Yao MECH3310 Lecture 8 Ch 5.15.3 27/09/2016
1
Transient Conduction
A heat transfer process for which the temperature varies with time, as well
as location within a solid.
It is initiated whenever a system experiences a chang
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
Extended Surfaces (Fins)
S. Yao MECH3310 Lecture 7 Ch 3.6 22/09/2016
1
Fins are everywhere:
Some typical fin configurations: http:/www.youtube.com/watch?v=c9HdoCZNlTg
S. Yao MECH3310 Lecture 7 Ch 3.6 22/09/2016
2
An extended surface (fin) is a solid with
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
Conduction: Fundamentals
S. Yao MECH3310 Lecture 3 Ch 1.31.4 08/09/2016
1
Fouriers Law
A rate equation that allows determination of the conduction heat flux
from knowledge of the temperature distribution in a medium
Its most general (vector) form for m
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Spring 2015
S.Yao
Handout 8
Homework Assignment 7
Due: 17/04/2015
1. Water is to be heated from 10 C to 40 C as it flows through a 5cminnerdiameter, 5mlomg tube. The tube is equipped with an electric resistance heater that provides uniform
he
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Spring 2015
S.Yao
Handout 7
Homework Assignment 6
Due: 10/04/2015
1. A flat plate of width 1 m is maintained at a uniform surface temperature of T s = 147 C by
using indenpendently controlled, heatgenerating rectangular modules ( = 2300 kg/m3, c
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Spring 2015
S.Yao
Handout 6
Homework Assignment 5
Due: 27/03/2015
1. In areas where the air temperature remains below 0 C for prolonged periods of time, the
freezing of water in underground is a major concern. Fortunately, the soil remains
relati
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH231 Spring 2015
S.Yao
Handout 4
Homework Assignment 3
Due: 06/03/2015
1. Consider a steam pipe of length of 10 m, inner and outer radius of 5 cm and 6 cm,
respectively. The thermal conductivity of the pipe is 12.5 W/mC. Steam is flowing through
the pi
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Spring 2015
S.Yao
Handout 3
Homework Assignment 2
Due: 27/02/2015
1. Consider a plane composite wall that is composed of two materials of A and B: thermal
conductivity k A = 0.1 W/mK, thickness L A = 10 mm; thermal conductivity k B = 0.06 W/mK,
t
The Hong Kong University of Science and Technology
heat
MECH 3310

Spring 2014
MECH3310 Spring 2015
S.Yao
Handout 2
Homework Assignment 1
Due: 13/02/2015
1. A temperature difference of 85C is imposed across a fiberglass layer of 10 cm thickness.
The thermal conductivity of the fiberglass is 0.035 W/mC. Compute the heat transferred
t