PROBLEM 3.31
KNOWN: Size and surface temperatures of a cubical freezer. Materials, thicknesses and interface
resistances of freezer wall.
FIND: Cooling load.
SCHEMATIC:
Lins = 100 mm
Freezer
Lst = 6.35 mm
Lal = 6.35 mm
Ts,o = 22oC
Cork
Ts,i = -6oC
R = 2.5

4-32
Chapter 7 l External Flow
The rate of heat transfer from the fth heater is then
gm, = (74 WIm2 - K x 0.25 m 67 W/m2 - K x 0.20 m)
X 1 m(230 25)C
qcouv,5 : 1050 W
Similarly, the power requirement for the sixth heater may be obtained by subtracting the

I Problem
The therrnophysical properties of the bar are p =
2600 kg/m3, c = 1030 J/kg-K, and k = 3.50 W/m-K.
(a) How long should the bar remain in the bath in
order that, when it is removed and allowed to equi-
librate while isolated from any surroundings

Heat Transfer, 6502481
Name: Prof. F. J. Diez
9/21/2016
Quiz No. 1
An electric heater with the total surface area of 0.25 m2 and emissivity 0.75 is in a room where the air has a
temperature of 20 C and the walls are at 10 C. When the heater consumes 500 W

MECHANICAL ENGINEERING LAB
MARCH 1, 2017
Materials Testing Laboratory MAE
Sachin Duggal
Department of Mechanical and Aerospace Engineering
Rutgers University, Piscataway, New Jersey 08854
In this lab experiment, we are to
determine
characteristic
mechanic

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ARENA Simulation Results
Class2016 - License: 2957000133
Summary for Replication 1 of 1
Project: Unnamed Project
execution date : 5/ 8/2017
Analyst: Class2016
revision date: 5/ 8/2017
Replication ended at time
Base Time Units: Minutes
Run
Model
: 5000.0 M

ARENA Simulation Results
Class2016 - License: 2957000133
Summary for Replication 1 of 1
Project: Unnamed Project
execution date : 5/ 8/2017
Analyst: Class2016
revision date: 5/ 8/2017
Replication ended at time
Base Time Units: Minutes
Run
Model
: 5000.0 M

ARENA Simulation Results
Class2016 - License: 2957000133
Summary for Replication 1 of 1
Project: Unnamed Project
execution date : 5/ 8/2017
Analyst: Class2016
revision date: 5/ 8/2017
Replication ended at time
Base Time Units: Minutes
Run
Model
: 5000.0 M

I Problems
(d) What advantage, if any, is there in not making
Ax = Ay for this situation?
With Ax = Ay = 2 mm, calculate the temperature
eld within the plate and the rate of heat transfer
from the plate. Under no circumstances may the
temperature at any l

4-36
Chapter 7 l External Flow
7.4.2 Convection Heat Transfer
Experimental results for the variation of the local Nusselt number with 0 are shown in
Figure 7.10 for the cylinder in a cross ow of air. Not unexpectedly, the results are strongly
inuenced by

PROBLEM 3.20
KNOWN: Window surface area and thickness, inside and outside heat transfer coefficients, outside
and passenger compartment temperatures.
FIND: Heat loss through the windows for high and low inside heat transfer coefficients.
SCHEMATIC:
T,o =

PROBLEM 3.10
KNOWN: A layer of fatty tissue with fixed inside temperature can experience different
outside convection conditions.
FIND: (a) Ratio of heat loss for different convection conditions, (b) Outer surface
temperature for different convection cond

PROBLEM 3.48
KNOWN: Inner and outer radii of a tube wall which is heated electrically at its outer surface
and is exposed to a fluid of prescribed h and T. Thermal contact resistance between heater
and tube wall and wall inner surface temperature.
FIND: H

PROBLEM 3.68
KNOWN: Dimensions of spherical, stainless steel liquid oxygen (LOX) storage container. Boiling
point and latent heat of fusion of LOX. Environmental temperature.
FIND: Thermal isolation system which maintains boil-off below 1 kg/day.
SCHEMATI

PROBLEM 3.132
KNOWN: Thermal conductivity and diameter of a pin fin. Value of the heat transfer coefficient and
fin efficiency.
FIND: (a) Length of fin, (b) Fin effectiveness.
SCHEMATIC:
D = 4 mm
f = 0.65
L
x
k = 160 W/mK
h = 220 W/m2K
ASSUMPTIONS: (1) St

PROBLEM 3.82
KNOWN: Diameter, thermal conductivity and microbial energy generation rate in cylindrical hay
bales. Ambient conditions.
FIND: The maximum hay temperature for q = 1, 10, and 100 W/m3.
SCHEMATIC:
Air
T = 0C, h = 25 W/m 2K
.
Ts
q = 1, 10 or 100

PROBLEM 3.5
KNOWN: Thermal conductivities and thicknesses of original wall, insulation layer, and glass layer.
Interior and exterior air temperatures and convection heat transfer coefficients.
FIND: Heat flux through original and retrofitted walls.
SCHEMA

PROBLEM 3.55
KNOWN: Long rod experiencing uniform volumetric generation of thermal energy, q, concentric
with a hollow ceramic cylinder creating an enclosure filled with air. Thermal resistance per unit
length due to radiation exchange between enclosure s

PROBLEM 3.96
KNOWN: Cylindrical shell with uniform volumetric generation is insulated at inner surface
and exposed to convection on the outer surface.
FIND: (a) Temperature distribution in the shell in terms of ri , ro , q, h, T and k, (b)
Expression for

PROBLEM 3.111
KNOWN: Surface conditions and thickness of a solar collector absorber plate. Temperature of
working fluid.
FIND: (a) Differential equation which governs plate temperature distribution, (b) Form of the
temperature distribution.
SCHEMATIC:
ASS

392 Chapter 6 I Introduction to Convection
always be treated as incompressible, density variations in owing gases should be considered
when the velocity approaches or exceeds the speed of sound. Specically, a gradual transition
from incompressible to comp