HEAT+MASS TRANSFER:FUND.+APPL.
6th Edition
ISBN: 9780073398198
Author: CENGEL
Publisher: RENT MCG
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Textbook Question
Chapter 4, Problem 175P
Consider a 7.6-cm-diameter cylindrical lamb meat chunk 1030 kWm3,
(a) 136 min
(b) 21.2 min
(c) 13.6 min
(d) 11.0 min
(e) 8.5 min
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An ordinary egg can be approximated as a 5.5-cm-diameter sphere whose thermal conductivity of roughly
k = 0.6-
W
mk
overall density of p = 1000; and heat capacity of C₂ = 3000-
kg
m²
The egg is initially at a uniform temperature of T₂ = 10°C and is dropped into boiling water at T..
= 90°C
W
- determine how long it will take for the egg to
m²K
Taking the convective heat transfer coefficient to be h
reach T = 70°C.
In solving the problem, please follow the steps below.
For the Lump Model
In solving this problem, please use the lump model method (ignoring the requirement of small Biot
number and discuss the outcomes,
1.
2. Compute the characteristic length Lc
Compute the volume and surface area of the sphere (as the egg model)
Vol
As
3. Compute the diffusivity α =
= 10-
k
p Cp
=
J
kgk
Compute non-dimensional excessive temperature 0
=
h Lc
k
4. Compute the Biot number using the characteristic length found above Bi
=
T-Too
5.
Ti-Too
6.
Calculate the Fourier number from the equation =…
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sheet No.3.pdf
Homework 01-03 -2021
one-dimensional heat transfer and disregarding radiation, determine the
rate of heat transfer through the wall.
Q4/ Steam at Te1-320°C flows in a cast iron pipe (k=80W/m.°C) whose
inner and outer diameters are D =5cm, and D=5.5cm, respectively. The
pipe is covered with 3 cm thick glass wool insulation with
k=0.05W/m.°C. Heat is lost to the surroundings at T02=5°C_by natural
convection and radiation, with a combined heat transfer coefficient to be
h,=18W/m.C. Taking the heat transfer coefficient inside the pipe to be
h,=60W/m.C, determine the rate of heat loss from the steam per unit
length of the pipe. Also determine the temperature drops across the pipe
shell and the insulation.
05/ Determine the overall heat transfer coefficient U based on the outer
surface of a D=2.5cm, and D=3.34 cm steel pipe (k=54.0W/m.°C) for
the following conditions: inside and outside heat transfer coefficients are
1200W/m."C. and 2000W/m."C…
Example: 0.5 kg of water per minute is
heated from 20° to 40°C when passed
through a tube of 2.5 cm diameter steel pipe.
The pipe surface temperature is maintained at
110°C by condensing steam on its surface.
Find out the length of the pipe required. The
properties of water at mean temperature of
70°C are given below:
p = 978 kg/m²
k= 0.575 W/m. K
Cp = 4200 J/kg. K
v = 0.415 x 10-6 m²/sec
Chapter 4 Solutions
HEAT+MASS TRANSFER:FUND.+APPL.
Ch. 4 - What is the physical significance of the Biot...Ch. 4 - What is lumped system analysis? When is it...Ch. 4 - In what medium is the lumped system analysis more...Ch. 4 - For which solid is the lumped system analysis more...Ch. 4 - For which kinds of bodies made of the same...Ch. 4 - Consider heat transfer between two identical hot...Ch. 4 - Consider heat transfer between two identical hot...Ch. 4 - Consider a hot baked potato on a plate. The...Ch. 4 - Consider a potato being baked in an oven that is...Ch. 4 - Consider two identical 4-kg pieces of roast beef....
Ch. 4 - Consider a sphere and a cylinder of equal volume...Ch. 4 - Obtain relations for the characteristic lengths of...Ch. 4 - Obtain a relation for the time required for a...Ch. 4 - A brick of 20310257mm in dimension is being burned...Ch. 4 - Prob. 15PCh. 4 - Prob. 16PCh. 4 - Prob. 17PCh. 4 - Metal plates...Ch. 4 - Prob. 19PCh. 4 - Prob. 20PCh. 4 - Prob. 21PCh. 4 - A 6-mm-thick stainless steel strip...Ch. 4 - After heat treatment, the 2-cm-thick metal plates...Ch. 4 - A long copper rod of diameter 2.0 cm is initially...Ch. 4 - Prob. 25PCh. 4 - Steel rods...Ch. 4 - Prob. 27PCh. 4 - Prob. 28PCh. 4 - To warm up some milk for a baby, a mother pours...Ch. 4 - A person is found dead at 5 p.m. in a room whose...Ch. 4 - Prob. 31PCh. 4 - In an experiment, the temperature of a hot gas...Ch. 4 - Prob. 33PCh. 4 - Pulverized coal particles are used in oxy-fuel...Ch. 4 - Oxy-fuel combustion power plants use pulverized...Ch. 4 - Plasma spraying is a process used for coating a...Ch. 4 - Consider a spherical shell satellite with outer...Ch. 4 - Prob. 38PCh. 4 - Prob. 39PCh. 4 - Prob. 40EPCh. 4 - Consider a sphere of diameter 5 cm, a cube of side...Ch. 4 - Prob. 42PCh. 4 - An egg is to be cooked to a certain level of...Ch. 4 - What is an infinitely long cylinder? When is it...Ch. 4 - What is the physical significance of the Fourier...Ch. 4 - Prob. 46CPCh. 4 - Prob. 47CPCh. 4 - The Biot number during a heat transfer process...Ch. 4 - A body at an initial temperature of Ti, is brought...Ch. 4 - Prob. 50PCh. 4 - In a meat processing plant, 2-cm-thick steaks...Ch. 4 - Prob. 52PCh. 4 - Prob. 53PCh. 4 - Prob. 54PCh. 4 - Prob. 55PCh. 4 - Layers of 23-cm-thick meat slabs...Ch. 4 - Prob. 57PCh. 4 - Prob. 58PCh. 4 - Prob. 59PCh. 4 - Prob. 60PCh. 4 - Prob. 61PCh. 4 - Prob. 62EPCh. 4 - Prob. 63PCh. 4 - Prob. 64PCh. 4 - Prob. 65PCh. 4 - Prob. 66PCh. 4 - A 30-cm-diameter, 4-m-high cylindrical column of a...Ch. 4 - Prob. 68PCh. 4 - Prob. 69PCh. 4 - Prob. 70PCh. 4 - For heat transfer purposes, an egg can be...Ch. 4 - Citrus fruits are very susceptible to cold...Ch. 4 - Chickens with an average mass of 1.7 kg...Ch. 4 - Prob. 74PCh. 4 - Prob. 75PCh. 4 - Prob. 76PCh. 4 - Oranges of 2.5-in-diameter...Ch. 4 - Prob. 78PCh. 4 - Prob. 79PCh. 4 - Prob. 80PCh. 4 - Prob. 81PCh. 4 - A 9-cm-diameter potato...Ch. 4 - In Betty Crocker s Cookbook, it is stated that it...Ch. 4 - Prob. 84PCh. 4 - Under what conditions can a plane wall be treated...Ch. 4 - What is a semi-infinite medium? Give examples of...Ch. 4 - Consider a hot semi-infinite solid at an initial...Ch. 4 - Prob. 88EPCh. 4 - Prob. 89PCh. 4 - In areas where the air temperature remains below...Ch. 4 - Prob. 91PCh. 4 - A highway made of asphalt is initially at a...Ch. 4 - A thick aluminum block initially at 20C is...Ch. 4 - Prob. 94PCh. 4 - A thick wall made of refractory bricks...Ch. 4 - Prob. 96PCh. 4 - Prob. 97PCh. 4 - A thick wood slab (k=0.17W/m.K,=1.2810-7m2/s) and...Ch. 4 - Prob. 99PCh. 4 - Prob. 100PCh. 4 - Prob. 101PCh. 4 - Prob. 102PCh. 4 - Prob. 103PCh. 4 - Prob. 104PCh. 4 - Prob. 105PCh. 4 - A barefooted person whose feet are at 32C steps on...Ch. 4 - What is the product solution method? How is it...Ch. 4 - How is the product solution used to determine the...Ch. 4 - Prob. 109CPCh. 4 - Consider a short cylinder whose top and bottom...Ch. 4 - Prob. 111PCh. 4 - Prob. 112PCh. 4 - Prob. 113PCh. 4 - A hot dog can be considered to be a cylinder 5 in...Ch. 4 - Prob. 115PCh. 4 - Prob. 116PCh. 4 - A 2-cm-high cylindrical ice block...Ch. 4 - Prob. 118PCh. 4 - Prob. 119PCh. 4 - Prob. 120PCh. 4 - Prob. 121PCh. 4 - Prob. 122PCh. 4 - Prob. 123PCh. 4 - Prob. 124CPCh. 4 - How does refrigeration prevent or delay the...Ch. 4 - What are the environmental factors that affect the...Ch. 4 - What is the effect of cooking on the...Ch. 4 - Prob. 128CPCh. 4 - Prob. 129CPCh. 4 - Prob. 130CPCh. 4 - Prob. 131CPCh. 4 - How does the rate of freezing affect the...Ch. 4 - Prob. 133CPCh. 4 - Prob. 134CPCh. 4 - Prob. 135CPCh. 4 - Prob. 136CPCh. 4 - Prob. 137CPCh. 4 - Prob. 138PCh. 4 - Chickens with an average mass of 2.2 kg and...Ch. 4 - Prob. 140EPCh. 4 - Prob. 141PCh. 4 - Prob. 142PCh. 4 - A long roll of 2-m-wide and 0.5-cm-thick 1-Mn...Ch. 4 - Prob. 144PCh. 4 - Prob. 145PCh. 4 - Prob. 146PCh. 4 - During a picnic on a hot summer day, the only...Ch. 4 - Two metal rods are being heated in an oven with...Ch. 4 - Stainless steel ball bearings...Ch. 4 - Prob. 150PCh. 4 - Prob. 151PCh. 4 - In Betty crockers Cookbook, it is stated that it...Ch. 4 - A watermelon initially at 35C is to be cooled by...Ch. 4 - Prob. 154PCh. 4 - Prob. 155PCh. 4 - Prob. 156PCh. 4 - Prob. 157PCh. 4 - Prob. 158PCh. 4 - Prob. 159PCh. 4 - Prob. 160PCh. 4 - Prob. 161PCh. 4 - Prob. 162PCh. 4 - Prob. 163PCh. 4 - Lumped system analysis of transient heat...Ch. 4 - Prob. 165PCh. 4 - Prob. 166PCh. 4 - An 18-cm-long, 16-cm-wide, and 12-cm-high hot iron...Ch. 4 - Prob. 168PCh. 4 - Prob. 169PCh. 4 - Prob. 170PCh. 4 - Prob. 171PCh. 4 - Prob. 172PCh. 4 - A long 18-cm-diameter bar made of hardwood...Ch. 4 - Consider a 7.6-cm-long and 3-cm-diameter...Ch. 4 - Consider a 7.6-cm-diameter cylindrical lamb meat...Ch. 4 - Prob. 176PCh. 4 - A small chicken (k=0.45W/m.K,=0.1510-6m2/s) and...Ch. 4 - A potato may be approximated as a 5.7-cm-diameter...Ch. 4 - When water, as in a pond or lake, is heated by...Ch. 4 - A large chunk of tissue at 35C with a thermal...Ch. 4 - Prob. 181PCh. 4 - Citrus trees are very susceptible to cold weather,...
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