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
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
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
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 fi
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
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
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 itsel
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 tempera
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 radiati
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 ar
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.
Assumpt
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
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.
Assumptio
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 generate
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
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 deter
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 solvi
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
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
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.
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 s
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 propert
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
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
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
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
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 b
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