Chapter 1 Basics of Heat Transfer
1-84 A styrofoam ice chest is initially filled with 40 kg of ice at 0C. The time it takes for the ice in the
chest to melt completely is to be determined.
Assumptions 1 Steady operating conditions exist. 2 The inner and o
Chapter 10 Boiling and Condensation
10-30 Cold water enters a steam generator at 15C and is boiled, and leaves as saturated vapor at Tsat =
100C. The fraction of heat used to preheat the liquid water from 15C to saturation temperature of 100C
is to be det
Chapter 5 Numerical Methods in Heat Conduction
5-32 The handle of a stainless steel spoon partially immersed in boiling water loses heat by convection and
radiation. The finite difference formulation of the problem is to be obtained, and the tip temperatu
Chapter 12 Radiation Heat Transfer
12-97 A solar collector consists of a horizontal copper tube enclosed in a concentric thin glass tube. The
annular space between the copper and the glass tubes is filled with air at 1 atm. The rate of heat loss from
the
Chapter 11 Fundamentals of Thermal Radiation
11-41 The variation of emissivity of a surface at a specified temperature with wavelength is given. The
average emissivity of the surface and its emissive power are to be determined.
Analysis The average emissi
Chapter 12 Radiation Heat Transfer
12-96 A simple solar collector is built by placing a clear plastic tube around a garden hose. The rate of heat
loss from the water in the hose by natural convection and radiation is to be determined.
Assumptions 1 Steady
Chapter 9 Natural Convection
9-107 An electric hot water heater is located in a small room. A hot water tank insulation kit is available
for $30. The payback period of this insulation to pay for itself from the energy it saves is to be determined.
Assumpt
Chapter 11 Fundamentals of Thermal Radiation
Radiation Properties
11-36C The emissivity is the ratio of the radiation emitted by the surface to the radiation emitted by a
blackbody at the same temperature. The fraction of radiation absorbed by the surface
Chapter 12 Radiation Heat Transfer
12-95 A double-pane window consists of two sheets of glass separated by an air space. The rates of heat
transfer through the window by natural convection and radiation are to be determined.
Assumptions 1 Steady operating
Chapter 8 Internal Forced Convection
Review Problems
8-61 Geothermal water is supplied to a city through stainless steel pipes at a specified rate. The electric
power consumption and its daily cost are to be determined, and it is to be assessed if the fri
Chapter 11 Fundamentals of Thermal Radiation
11-35 A small surface is subjected to uniform incident radiation. The rates of radiation emission through
two specified bands are to be determined.
Assumptions The intensity of incident radiation is constant.
A
Chapter 12 Radiation Heat Transfer
which is more than 30 Btu/h. Therefore, the assumed temperature of 85F for the glass cover is high.
Repeating the calculations with lower temperatures (including the evaluation of properties), the glass cover
temperature
Chapter 9 Natural Convection
9-106 A cold aluminum canned drink is exposed to ambient air. The time it will take for the average
temperature to rise to a specified value is to be determined.
Assumptions 1 Steady operating conditions exist. 2 Air is an ide
Chapter 8 Internal Forced Convection
8-60 A computer is cooled by a fan blowing air through its case. The flow rate of the air, the fraction of the
temperature rise of air that is due to heat generated by the fan, and the highest allowable inlet air
tempe
Chapter 11 Fundamentals of Thermal Radiation
11-34 A small surface emits radiation. The rate of radiation energy emitted through a band is to be
determined.
60
Assumptions Surface A emits diffusely as a blackbody.
Analysis The rate of radiation emission f
Chapter 12 Radiation Heat Transfer
12-94E The circulating pump of a solar collector that consists of a horizontal tube and its glass cover fails.
The equilibrium temperature of the tube is to be determined.
30 Btu/h.ft
Assumptions 1 Steady operating condi
Chapter 9 Natural Convection
Then the total heat loss from the duct can be expressed as
&
&
&
&
Q
= Q +Q
+ Q = [(hA) + (hA)
total
top
bottom
side
top
bottom
+ (hA) side ](Ts T )
Substituting and solving for the surface temperature,
3.41214 Btu/h
180 W
Chapter 8 Internal Forced Convection
Properties The properties of water at the bulk mean fluid temperature of
Tb, ave = (54 + 140) / 2 = 97F 100F are (Table A-9E)
= 62.0 lbm/ft 3
250F
k = 0.363 Btu/h.ft.F
= 0.738 10 -5 ft 2 /s
Water
54F
0.7 lbm/s
C p =
Chapter 11 Fundamentals of Thermal Radiation
11-33 Radiation is emitted from a small circular surface located at the center of a sphere. Radiation energy
streaming through a hole located on top of the sphere and the side of sphere are to be determined.
As
Chapter 12 Radiation Heat Transfer
H
Nu = 0.42 Ra 1 / 4 Pr 0.012
L
0.3
2m
= 0.42(8.083 10 4 ) 1 / 4 (0.7212) 0.012
0.03 m
T T
(80 32)C
&
= 534 W
Q = kNuAs 1 2 = (0.02779 W/m.C)(2.001)(6 m 2 )
0.03 m
L
12-72
0.3
= 2.001
Chapter 9 Natural Convection
9-105E The components of an electronic system located in a horizontal duct of rectangular cross section is
cooled by natural convection. The heat transfer from the outer surfaces of the duct by natural convection
and the avera
Chapter 8 Internal Forced Convection
Assumptions 1 Steady flow conditions exist. 2 Heat generated is uniformly distributed over the two
surfaces of the PCB. 3 Air is an ideal gas with constant properties. 4 The pressure of air is 1 atm.
Properties We assu
Chapter 9 Natural Convection
9-104E The components of an electronic system located in a horizontal duct of circular cross section is
cooled by forced air. The heat transfer from the outer surfaces of the duct by natural convection and the
average temperat
Chapter 12 Radiation Heat Transfer
12-93 A solar collector is considered. The absorber plate and the glass cover are maintained at uniform
temperatures, and are separated by air. The rate of heat loss from the absorber plate by natural convection
and radi
Chapter 11 Fundamentals of Thermal Radiation
11-32 Radiation is emitted from a small circular surface located at the center of a sphere. Radiation energy
streaming through a hole located on top of the sphere and the side of sphere are to be determined.
As
Chapter 11 Fundamentals of Thermal Radiation
11-31 A surface is subjected to radiation emitted by another surface. The solid angle subtended and the rate
at which emitted radiation is received are to be determined.
Assumptions 1 Surface A1 emits diffusely
Chapter 12 Radiation Heat Transfer
12-92 Two concentric spheres which are maintained at uniform temperatures are separated by air at 1 atm
pressure. The rate of heat transfer between the two spheres by natural convection and radiation is to be
determined.
Chapter 9 Natural Convection
9-103E The components of an electronic device located in a horizontal duct of rectangular cross section is
cooled by forced air. The heat transfer from the outer surfaces of the duct by natural convection and the
average tempe