ME 225 C Heat Transfer: Homework 8
Due: Friday, April 4th
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. Water enters a tube with a flow rate of 0.015 kg/s and inlet temperature of 20C. The tube has a le
Due: Friday, April 25th
ME 225 C Heat Transfer: Homework 10
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. An infrared thermometer allows non-contact measurement of the temperature of a surface by sensin
PROBLEM 8.59
KNOWN: Thin-walled, tall stack discharging exhaust gases from an oven into the environment.
FIND: (a) Outlet gas and stack surface temperatures, Tm,o and Ts,o, and (b) Effect of wind temperature
and velocity on Tm,o.
SCHEMATIC:
ASSUMPTIONS: (
PROBLEM 13.37
KNOWN: Diameter and pitch of in-line tubes occupying evacuated space between parallel plates of
&
prescribed temperature. Temperature and flowrate m of water through the tubes.
&
&
FIND: (a) Tube surface temperature Ts for m = 0.20 kg/s, (b)
PROBLEM 3.150
KNOWN: Copper heat sink dimensions and convection conditions.
FIND: (a) Maximum allowable heat dissipation for a prescribed chip temperature and interfacial
chip/heat-sink contact resistance, (b) Effect of fin length and width on heat dissip
PROBLEM 11.18
KNOWN: Inner tube diameter (D = 0.02 m) and fluid inlet and outlet temperatures corresponding to
design conditions for a counterflow, concentric tube heat exchanger. Overall heat transfer coefficient (U
= 500 W/m2K) and desired heat rate (q
PROBLEM 3.79
KNOWN: Wall of thermal conductivity k and thickness L with uniform generation q ; strip heater
with uniform heat flux qo ; prescribed inside and outside air conditions (hi, T,i, ho, T,o).
FIND: (a) Sketch temperature distribution in wall if n
PROBLEM 9.18
KNOWN: During a winter day, the window of a patio door with a height of 1.8 m and width of 1.0 m
shows a frost line near its base.
FIND: (a) Explain why the window would show a frost layer at the base of the window, rather than at
the top, an
PROBLEM 5.10
KNOWN: Thickness and properties of flaked food product. Conveyor length. Initial flake
temperature. Ambient temperature and convection heat transfer coefficient. Final product temperature.
FIND: Required conveyor velocities for thick and thin
PROBLEM 3.4
KNOWN: Desired inner surface temperature of rear window with prescribed inside and outside air
conditions.
FIND: (a) Heater power per unit area required to maintain the desired temperature, and (b) Compute and
plot the electrical power require
PROBLEM 12.10
7
2
KNOWN: Daytime solar radiation conditions with direct solar intensity Idir = 2.10 10 W/m sr
-5
within the solid angle subtended with respect to the earth, S = 6.74 10 sr, and diffuse intensity
2
Idif = 70 W/m sr.
FIND: (a) Total solar ir
PROBLEM 1.9
KNOWN: Width, height, thickness and thermal conductivity of a single pane window and
the air space of a double pane window. Representative winter surface temperatures of single
pane and air space.
FIND: Heat loss through single and double pane
Due: Friday, May 9th
ME 225 C Heat Transfer: Homework 11
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. Water flowing through a large number of long, circular, thin-walled tubes is heated by means of hot
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ME 225 Fall 2012 Name
2. (25 points) Consider a furnace with an isothermal wall temperature of T1=2000K. A small aperture is
cut in the wall of the furnace with area A.=0.00l m2. A perfect diffuse reector (p=1), A2, is placed 1
m from the aperture a
Due: Friday, Jan. 31st
ME 225C: Homework 2
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. Electronics on a 0.5 m diameter spherical interplanetary probe dissipate 150 W. The emissivity of the
probe is 0.
Homework 2: Problem 1
Homework 2: Problem 2
Homework 2: Problem 3
The greater convection of the nonconductive fluid allows much more heat to be removed.
Homework 2: Problem 4
Ts=60.5C
Homework 2: Problem 5
Homework 2: Problem 6
Due: Friday, Feb. 7th
ME 225 C Heat Transfer: Homework 3
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. The wall of a spacecraft is 0.05 m thick and has a conductivity of 10 W/mK. The inner surface is
ma
Due: Friday, Feb. 21st
ME 225 C Heat Transfer: Homework 5
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. A long constantan wire (kw=200 W/mK) of 1-mm diameter
is butt welded to the surface of a large cop
Due: Friday, Feb. 28th
ME 225 C Heat Transfer: Homework 6
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. Carbon steel (AISI 1010) shafts of 0.05-m in diameter are heat treated in a gas-fired furnace whos
Due: Friday, Feb. 14th
ME 225 C Heat Transfer: Homework 4
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. Current flows in circular (k1=50 W/mK) wire and produces a uniform
volumetric heat generation, q =
if t %
1. (30 points) Current flows in circular (k]=50 W/m-K) wire and produces a uniform
volumetric heat generation, q'=lO6 W/m3. The diameter of the wire is D=10 mm.
The wire is coated by insulation of thickness 1:5 mm, with a thermal conductivity
k=10
Due: Friday, March 14th
ME 225 C Heat Transfer: Homework 7
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. The local convection coefficient for laminar free convection from a heated surface may be express
ME 225 Spring 2013 Name
3. (30 pts) An automobile radiator may be viewed as a cross~0w heat exchanger. Water enters
the radiator with a ow rate of mh 20.05 kg/s and a inlet temperature, 7).;12125°C. It exits with
an outlet temperature of T(,Eh=55°C. The w
Due: Friday, April 18th
ME 225 C Heat Transfer: Homework 9
For all problems, please include a sketch of the problem and be sure to state your assumptions.
1. A simple counterflow heat exchanger is formed by fusing
two pipes together. 4.00 kg/s of oil flow
PROBLEM 6.7
KNOWN: Distribution of local convection coefficient for obstructed parallel flow over a flat
plate.
FIND: Average heat transfer coefficient and ratio of average to local at the trailing edge.
SCHEMATIC:
ANALYSIS: The average convection coeffic