PROBLEM 1.5
KNOWN: Inner and outer surface temperatures of a glass window of prescribed dimensions.
FIND: Heat loss through window.
SCHEMATIC:
ASSUMPTIONS: (1) One-dimensional conduction in the x-direction, (2) Steady-state
conditions, (3) Constant proper
PROBLEM 2.8
KNOWN: One-dimensional system with prescribed thermal conductivity and thickness.
FIND: Unknowns for various temperature conditions and sketch distribution.
SCHEMATIC:
ASSUMPTIONS: (1) Steady-state conditions, (2) One-dimensional conduction, (
ME 335 (HEAT TRANSFER), FALL 2012, EXAM I
OPEN BOOK, 2 SHEETS OF HAND WRITTEN NOTES
Department of Mechanical Engineering, University of Michigan
Name:
Pledge:
PROBLEM 1 (30%)
Consider heat loss from a human body as depicted in Figure Pr.1 as a cylinder of
PROBLEM 4.42.FAM
GIVEN:
A gridded silicon electric heater is used in a microelectromechanical device, as shown in Figure Pr.4.42.
The heater has an electrical resistance Re and a voltage is applied resulting in the Joule heating. For
testing purposes, the
PROBLEM 3.50.FAM
GIVEN:
During solidication, as in casting, the melt may locally drop to temperatures below the solidication temperature Tls , before the phase change occurs. Then the melt is in a metastable state (called supercooled liquid)
and the nucle
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PROBLEM 3.110
KNOWN: Temperature sensing probe of thermal conductivity k, length L and diameter D is mounted
on a duct wall; portion of probe Li is exposed to water stream at T,i while other end is exposed to
ambient air at T,o ; convection coefficients h
PROBLEM 3.27
KNOWN: Operating conditions for a board mounted chip.
FIND: (a) Equivalent thermal circuit, (b) Chip temperature, (c) Maximum allowable heat dissipation for
dielectric liquid (ho = 1000 W/m2K) and air (ho = 100 W/m2K). Effect of changes in ci
PROBLEM 6.6
6.9
KNOWN: Variation of local convection coefficient with distance x from a heated plate with a
uniform temperature Ts.
FIND: (a) An expression for the average coefficient h12 for the section of length (x2 - x1) in terms of
C, x1 and x2, and (
PROBLEM 1.62
KNOWN: Duct wall of prescribed thickness and thermal conductivity experiences prescribed heat flux
q at outer surface and convection at inner surface with known heat transfer coefficient.
o
FIND: (a) Heat flux at outer surface required to mai
PROBLEM 6.7
KNOWN: Radial distribution of local convection coefficient for flow normal to a circular
disk.
FIND: Expression for average Nusselt number.
SCHEMATIC:
ASSUMPTIONS: Constant properties
ANALYSIS: The average convection coefficient is
1
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PROBLEM 8.8
8.9
KNOWN: Velocity and temperature profiles for laminar flow in a parallel plate channel.
FIND: Mean velocity, um, and mean (or bulk) temperature, Tm, at this axial position. Plot the velocity
and temperature distributions. Comment on whether
PROBLEM 2.21
KNOWN: Diameter D, thickness L and initial temperature Ti of pan. Heat rate from stove to bottom
of pan. Convection coefficient h and variation of water temperature T(t) during Stage 1.
Temperature TL of pan surface in contact with water duri
ME 335 (HEAT TRANSFER), WINTER 2014, EXAM II
OPEN BOOK, 2 SHEETS OF HAND WRITTEN NOTES
Department of Mechanical Engineering, University of Michigan
PROBLEM 1 (33%)
GIVEN:
A disk of diameter D is electrically (Joule) heated at a rate of S e,J and its radia
PROBLEM 2.5
KNOWN: End-face temperatures and temperature dependence of k for a truncated cone.
FIND: Variation with axial distance along the cone of q x , q , k, and dT / dx.
x
SCHEMATIC:
ASSUMPTIONS: (1) One-dimensional conduction in x (negligible temper
PROBLEM 8.32
8.33
KNOWN: Flow rate, inlet temperature and desired outlet temperature of water passing through a tube of
prescribed diameter and surface temperature.
FIND: (a) Required tube length, L, for prescribed conditions, (b) Required length using tu
PROBLEM 12.20
12.18
2
KNOWN: Solar flux at outer edge of earths atmosphere, 1353 W/m .
FIND: (a) Emissive power of sun, (b) Surface temperature of sun, (c) Wavelength of maximum solar
emission, (d) Earth equilibrium temperature.
SCHEMATIC:
ASSUMPTIONS: (1
PROBLEM 3.118
KNOWN: Extended surface of rectangular cross-section with heat flow in the longitudinal direction.
FIND: Determine the conditions for which the transverse (y-direction) temperature gradient is
negligible compared to the longitudinal gradient
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ME 335 (HEAT TRANSFER), FALL 2013, EXAM I
OPEN BOOK, 2 SHEETS OF HAND WRITTEN NOTES
Department of Mechanical Engineering, University of Michigan
Name:
Pledge:
PROBLEM 1 (35%)
Consider cooling of human body by sweating. The average human surface area is 1.
ME 335 (HEAT TRANSFER), FALL 2013, EXAM I
OPEN BOOK, 2 SHEETS OF HAND WRITTEN NOTES
Department of Mechanical Engineering, University of Michigan
Name:
Pledge:
PROBLEM 1 (35%)
Consider cooling of human body by sweating. The average human surface area is 1.
ME 335 (HEAT TRANSFER), FALL 2013, EXAM II
OPEN BOOK, 2 SHEETS OF HAND WRITTEN NOTES
Department of Mechanical Engineering, University of Michigan
Name:
Pledge:
PROBLEM 1 (35%)
Hot-wire anemometer is used to measure the fluid velocity uf, , as shown in Fig
ME 335 (HEAT TRANSFER), WINTER 2013, EXAM II
OPEN BOOK, 2 SHEETS OF HAND WRITTEN NOTES
Department of Mechanical Engineering, University of Michigan
Name:
Pledge:
PROBLEM 1 (35%)
A rectangular-shaped radiant heater (surface 1) using Joule heating (S e,J )1
176
3.31
3.32
3.34
(3) Obtain an expression for the temperature distribution
T(x).
(b) What is the rate of heat transfer across the cone if it
is constructed of pure aluminum with x1 = 0.075 m,
T. : 100C,x2 = 0.225 m, and T2 = 20C?
From Figure 2.5 it is e
HW#4
Goal
This section of chapter three and this homework set focus on the physics behind
conduction. What is actually happening? How can we use this knowledge to predict
material properties?
Unfortunately, answering these questions is not a simple task.
ME 335 (HEAT TRANSFER), FALL 2012, EXAM II
OPEN BOOK, 2 SHEETS OF HAND WRITTEN NOTES
Department of Mechanical Engineering, University of Michigan
Name:
Pledge:
PROBLEM 1 (33%)
The ice rink in hockey arena is heated by surface convection (assume thermobuoy