Heat and Mass Transfer: Fundamentals and Applications
5th Edition
ISBN: 9780073398181
Author: Yunus A. Cengel Dr., Afshin J. Ghajar
Publisher: McGraw-Hill Education
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Chapter 4, Problem 70P
For heat transfer purposes, an egg can be considered to be a 5.5-cm- diameter sphere having the properties of water. An egg that is initially at 4.3°C is dropped into boiling water at 100°C. The heat transfer coefficient at the surface of the egg is estimated to be
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A pipe in a manufacturing plant is transporting superheated vapor at a mass flow rate of 0.3 kg/s. The pipe is 10 m long and has an inner diameter of 5 cm and a wall thickness of 6 mm. The pipe has a thermal conductivity of 17 W/m⋅K, and the inner pipe surface is at a uniform temperature of 120° C. The temperature drop between the inlet and exit of the pipe is 7° C, and the constant pressure specific heat of vapor is 2 190 J/kg⋅°C. If the air temperature in the manufacturing plant is 25° C, determine the heat transfer coefficient as a result of convection between the outer pipe surface and the surrounding air.
An ice chest whose outer dimensions are 30 cm*40 cm*40 cm is made of 3 cm thick Styrofoam (k = 0.033 W/m°C). Initially, the chest is filled with 30 kg of ice at 0 °C, and the inner surface temperature of the ice chest can be taken to be 0 °C at all times. The heat of fusion of water at 0 °C is 333.7 kJ/kg, and the surrounding ambient air is at 20 °C. Disregarding any heat transfer from the 40 cm*40 cm base of the ice chest, determine how long it will take for the ice in the chest to melt completely if the ice chest is subjected to (a) calm air and (b) winds at 30 km/h (assume the heat transfer coefficient on the front, back and top surfaces to be the same as that on the side surfaces). Use the thermophysical properties of air as follows: k = 25.5×10-3 W/mK, ν = 15×10-6 m2/s, α = 21.1×10-6 m2/s, and β = 3.43×10-3 K-1.
A 10 cm diameter aluminum ball is to be heated from 94°C to an average temperature of 140°C in 30 minutes. Taking the average density and specific heat of aluminum in this temperature range to be 2,700 kg/m3 and Cp = 0.91 kJ/kg-K, respectively, determine the ff: (Round off your final answers to two (2) decimal places.)
(a) the total amount of heat transferred to the ball in kJ =
(b) the average heat transfer rate to the aluminum ball in W =
(c) the average heat flux in W/m2 =
Chapter 4 Solutions
Heat and Mass Transfer: Fundamentals and Applications
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 - Metal plates...Ch. 4 - Prob. 18PCh. 4 - Prob. 19PCh. 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. 23PCh. 4 - Steel rods...Ch. 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. 27PCh. 4 - In an experiment, the temperature of a hot gas...Ch. 4 - Prob. 29PCh. 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. 34PCh. 4 - Prob. 35PCh. 4 - Prob. 36EPCh. 4 - Consider a sphere of diameter 5 cm, a cube of side...Ch. 4 - Prob. 38PCh. 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. 42CPCh. 4 - Prob. 43CPCh. 4 - Prob. 44CPCh. 4 - The Biot number during a heat transfer process...Ch. 4 - A body at an initial temperature of Ti, is brought...Ch. 4 - Prob. 47PCh. 4 - In a meat processing plant, 2-cm-thick steaks...Ch. 4 - Prob. 49PCh. 4 - Prob. 50PCh. 4 - Prob. 51PCh. 4 - Layers of 23-cm-thick meat slabs...Ch. 4 - Prob. 53PCh. 4 - Prob. 54PCh. 4 - Prob. 55EPCh. 4 - Prob. 56PCh. 4 - Prob. 57EPCh. 4 - Prob. 58PCh. 4 - A 30-cm-diameter, 4-m-high cylindrical column of a...Ch. 4 - Prob. 60PCh. 4 - Prob. 61PCh. 4 - Prob. 62PCh. 4 - Prob. 63PCh. 4 - Prob. 64PCh. 4 - Prob. 65PCh. 4 - Prob. 66PCh. 4 - Prob. 67PCh. 4 - Prob. 68PCh. 4 - Prob. 69PCh. 4 - For heat transfer purposes, an egg can be...Ch. 4 - Citrus fruits are very susceptible to cold...Ch. 4 - Prob. 72PCh. 4 - Prob. 73PCh. 4 - A 9-cm-diameter potato...Ch. 4 - Chickens with an average mass of 1.7 kg...Ch. 4 - Prob. 76PCh. 4 - In Betty Crocker s Cookbook, it is stated that it...Ch. 4 - Prob. 78PCh. 4 - Prob. 79PCh. 4 - Oranges of 2.5-in-diameter...Ch. 4 - Prob. 81EPCh. 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. 85EPCh. 4 - Prob. 86PCh. 4 - In areas where the air temperature remains below...Ch. 4 - Prob. 88PCh. 4 - A highway made of asphalt is initially at a...Ch. 4 - A thick aluminum block initially at 20C is...Ch. 4 - Prob. 91PCh. 4 - A thick wall made of refractory bricks...Ch. 4 - Prob. 93PCh. 4 - Prob. 94PCh. 4 - A thick wood slab (k=0.17W/m.K,=1.2810-7m2/s) and...Ch. 4 - Prob. 96PCh. 4 - Prob. 97PCh. 4 - Prob. 98PCh. 4 - Prob. 99PCh. 4 - Prob. 100PCh. 4 - Prob. 101PCh. 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. 105CPCh. 4 - Consider a short cylinder whose top and bottom...Ch. 4 - Prob. 107PCh. 4 - Prob. 108PCh. 4 - A hot dog can be considered to be a cylinder 5 in...Ch. 4 - Prob. 110PCh. 4 - Prob. 111PCh. 4 - A 2-cm-high cylindrical ice block...Ch. 4 - Prob. 113PCh. 4 - Prob. 114PCh. 4 - Prob. 115PCh. 4 - Prob. 116PCh. 4 - Prob. 117PCh. 4 - Prob. 118PCh. 4 - Prob. 119CPCh. 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. 123CPCh. 4 - Prob. 124CPCh. 4 - Prob. 125CPCh. 4 - Prob. 126CPCh. 4 - How does the rate of freezing affect the...Ch. 4 - Prob. 128CPCh. 4 - Prob. 129CPCh. 4 - Prob. 130CPCh. 4 - Prob. 131CPCh. 4 - Prob. 132CPCh. 4 - Prob. 133PCh. 4 - Prob. 134PCh. 4 - Chickens with an average mass of 2.2 kg and...Ch. 4 - Prob. 136EPCh. 4 - Prob. 137PCh. 4 - Prob. 138PCh. 4 - A long roll of 2-m-wide and 0.5-cm-thick 1-Mn...Ch. 4 - Prob. 140PCh. 4 - Prob. 141PCh. 4 - Prob. 142PCh. 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. 146PCh. 4 - Prob. 147PCh. 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. 150PCh. 4 - Prob. 151PCh. 4 - Prob. 152PCh. 4 - Prob. 153PCh. 4 - Prob. 154PCh. 4 - Prob. 155PCh. 4 - Prob. 156PCh. 4 - Prob. 157PCh. 4 - Prob. 158PCh. 4 - Prob. 159PCh. 4 - Lumped system analysis of transient heat...Ch. 4 - Prob. 161PCh. 4 - Prob. 162PCh. 4 - An 18-cm-long, 16-cm-wide, and 12-cm-high hot iron...Ch. 4 - Prob. 164PCh. 4 - Prob. 165PCh. 4 - Prob. 166PCh. 4 - Prob. 167PCh. 4 - Prob. 168PCh. 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. 172PCh. 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. 177PCh. 4 - Citrus trees are very susceptible to cold weather,...
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