Heat and Mass Transfer: Fundamentals and Applications
5th Edition
ISBN: 9780073398181
Author: Yunus A. Cengel Dr., Afshin J. Ghajar
Publisher: McGraw-Hill Education
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Textbook Question
Chapter 4, Problem 22P
A long copper rod of diameter 2.0 cm is initially at a uniform temperature of 100°C. It is now exposed to an airstream at 20°C with a heat transfer coefficient of’ 200 W/m2 K. How long would it take for the copper rod to cool to an average temperature of 25°C?
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
A 6 cm diameter sphere is initially at a temperature of 100C.
Later, this sphere was thrown into water at 800C.
Calculate how long it will take for the center temperature of the sphere to reach 500C by taking the convection heat transfer coefficient as 80W / m2K.
Thermal properties of sphere material:
k=0,627 W/moC a=0,151x10-6 m2/s
Consider a thin suspended hotplate that measures 0.4 mx 0.4 m. The isothermal plate has a mass of 3.75 kg, a specific heat of 2770
J/kg-K, and a temperature of 200°C. The ambient air temperature is 25°C and the surroundings temperature is 25°C.
If the convection coefficient is 6.4 W/m²-K and the emissivity of the plate is = 0.42, determine the time rate of change of the plate
temperature, dT/dt, when the plate temperature is 200°C. Evaluate the magnitude of the heat losses by convection and by radiation.
dT/dt = i
19radl = i
19conv
= i
K/s
W
W
The inner and outer surfaces of a 0.3 cm thick 1.8 m x 2.5 m window glass in winter
are 20°C and 1°C, respectively. If the thermal conductivity of the glass is 0.8 W/m-K,
determine the amount of heat loss through the glass over a period of 4 h. What
would your answer be if the glass were 0.6 cm thick?
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,...
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, mechanical-engineering and related others by exploring similar questions and additional content below.Similar questions
- A 6 cm diameter cylinder is initially at a temperature of 10 °C. Later, this cylinder was thrown into water at 80°C. Calculate how long it will take for the center temperature of the cylinder to reach 50 °C by taking the convection heat transfer coefficient as 80W / /m?K. Thermal properties of the cylinder material k=0,587 W/m°C wwww a = 0,13 x10 * m /s attachments Heisler diagrams for cylinder 1.0 F100 50 30 12 0.7 0.5 0.4 0.3 0.2 2.5 3.0 0.1 3 02 B hr 0.07 0.05 0.04 0.03 0,02 0.007 0.005 0.004 0.00 0.002 0.001 ! 2 3 468 101214 16 18 20 22 24 26 28 30 40 50 60 70 B0 90100 115 130 150200 300 kenle)= Fo 1.0 0.2 0.9 0.8 0.4 0.7 0.6 0.6 0.5 0.4 0.3 0.8 0.2 0.9 0.1 1.0 8.01 0.02 0.05 0.1 O.2 0.5 1.0 2 3 5 10 20 CA/hr)- Bi 50 100 T-Tarrow_forwardA solid plate, with a thickness of 15 cm and a thermal conductivity of 80 W/m-K, is being cooled at the upper surface by air. The air temperature is 10°C, while the temperatures at the upper and lower surfaces of the plate are 50 and 60°C, respectively. Determine the convection heat transfer coefficient of air at the upper surface and discuss whether the value is reasonable or not for force convection of air. Air, T. = 10°C T1 = 50°C T2 = 60°C L = 15 cmarrow_forwardOne end of a 0.3 m long steel rod is connected to a wall at 204°C. The other end is connected to a wall which is maintained at 93°C. Air is blown across the rod so that a heat transfer coefficient of 17 W/(m2 K) is maintained over the entire surface. If the diameter of the rod is 5 cm and the temperature of the air is 38°C, what is the net rate of heat loss to the air?arrow_forward
- (b) A transistor with a height of 0.4 cm and a diameter of 0.6 cm is mounted on a circuit board as shown in Figure 3. The transistor is cooled by air flowing over it with an average heat transfer coefficient of 30 W/m².K. If the air temperature is 55°C and the transistor case temperature is not to exceed 70°C, determine the amount of power this transistor can dissipate safely. Disregard any heat transfer from the transistor base. Air 55°C Power transistor 0.6 cm T, ≤ 70°C -0.4 c 0.4 cm- Figure 3arrow_forwardAn electric resistance space heater is designed such that it resembles a rectangular box 50 cm high, 80 cm long, and 15 cm wide filled with 45 kg of oil. The heater is to be placed against a wall, and thus heat transfer from its back surface is negligible. The surface temperature of the heater is not to exceed 75°C in a room at 25°C for safety considerations. Disregarding heat transfer from the bottom and top surfaces of the heater in anticipation that the top surface will be used as a shelf, determine the power rating of the heater in W. Take the emissivity of the outer surface of the heater to be 0.8 and the average temperature of the ceiling and wall surfaces to be the same as the room air temperature. Also, determine how long it will take for the heater to reach steady operation when it is first turned on (i.e., for the oil temperature to rise from 25°C to 75°C). State your assumptions in the calculations.arrow_forwardA person puts a few apples into the freezer at 15°C cool them quickly for guestswho are about to arrive. Initially, the apples are at a uniform temperature of 20°C,and the heat transfer coefficient on the surfaces is 8 W/m2·K. Treating the apples as9-cm-diameter spheres and taking their properties to be 840 kg/m3, Cp 3.81 kJ/kg·K, k = 0.418 W/m·K, and α =10-7 m2/s, determine the center and surface temperatures of the apples in 1 h. Also, determine the amount of heat transfer from each apple. Solve this problem using analytical one-term approximation method (notthe Heisler charts). Answer: Center: 11.2 ℃, Surface: 2.7 ℃, heat transfer: 17.2 kJarrow_forward
- When a rectangle steel block 0.45 m by 0.65 m by 0.7m is initially at 450C. It is suddenly immersed in an environment at 101C. Determine the temperature at the center of the block after 1.5 hour. The properties are; surface convection coefficient is 43 W/m 2 .K, k= 36 W/m.K and α=0.0399 m 2 /h.arrow_forwardA person is found dead at 5PM in a room whose temperature is 20°C. Thetemperature of the body is measured to be 25°C when found, Modeling thebody as a 30-cm-diameter, 1.70-m-long cylinder and the heat transfer coefficient estimated to be 8 W/m2·K. and using the lumped system analysis as a rough approximation, estimate the time of death of the person.arrow_forward2.5 cm-thick sheet of plastic initially at 21°C is placed between two heated steel plates that are maintained at 138°C. The plastic is to be heated just long enough for its midplane temperature to reach 132°C. If the thermal conductivity of the plastic is 1.1 × 10-3 W/(m K), the thermal diffusivity is 2.7 × 10-6 m2/s, and the thermal resistance at the interface between the plates and the plastic is negligible, calculate: (a) the required heating time, (b) the temperature at a plane 0.6 cm from the steel plate at the moment the heating is discontinued, and (c) tarrow_forward
- Hot water is being transported in a horizontal pipe (k = 0.15 W/m∙K, Di = 2.5 cm, Do = 4.5 cm), where the pipe inner surface temperature is at 100°C. A length of 2 m of the pipe outer surface is exposed to cool air at 12°C. Assuming that the properties of air can be evaluated at 40°C and 1 atm pressure, determine the outer surface temperature of the pipe. Is 40°C an appropriate film temperature for evaluation of the air properties?arrow_forwardAn experiment is to be conducted to determine heat transfer coefficient on the surfaces of tomatoes that are placed in cold water at 7°C. The tomatoes (k = 0.59 W/m·K, a =0.141 * 10-6 m2/s, r = 999 kg/m3, cp = 3.99 kJ/kg·K) with an initial uniform temperature of 30°C are spherical in shape with a diameter of 8 cm. After a period of 2 h, the temperatures at the center and the surface of the tomatoes are measured to be 10.0°C and 7.1°C, respectively. Using analytical one-term approximation method (not the Heisler charts), determine the heat transfer coefficient and the amount of heat transfer during this period if there are eight such tomatoes in water.arrow_forwardA 6 cm diameter cylinder is initially at a temperature of 10 °C. Later, this cylinder was thrown into water at 80°C. Calculate how long it will take for the center temperature of the cylinder to reach 50 °C by taking the convection heat transfer coefficient as 80W //m?K. Thermal properties of the cylinder material k=0,587 W/m°C a = 0,13x10-m² /sarrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
Elements Of ElectromagneticsMechanical EngineeringISBN:9780190698614Author:Sadiku, Matthew N. O.Publisher:Oxford University Press
Mechanics of Materials (10th Edition)Mechanical EngineeringISBN:9780134319650Author:Russell C. HibbelerPublisher:PEARSON
Thermodynamics: An Engineering ApproachMechanical EngineeringISBN:9781259822674Author:Yunus A. Cengel Dr., Michael A. BolesPublisher:McGraw-Hill Education
Control Systems EngineeringMechanical EngineeringISBN:9781118170519Author:Norman S. NisePublisher:WILEY
Mechanics of Materials (MindTap Course List)Mechanical EngineeringISBN:9781337093347Author:Barry J. Goodno, James M. GerePublisher:Cengage Learning
Engineering Mechanics: StaticsMechanical EngineeringISBN:9781118807330Author:James L. Meriam, L. G. Kraige, J. N. BoltonPublisher:WILEY
Elements Of Electromagnetics
Mechanical Engineering
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Oxford University Press
Mechanics of Materials (10th Edition)
Mechanical Engineering
ISBN:9780134319650
Author:Russell C. Hibbeler
Publisher:PEARSON
Thermodynamics: An Engineering Approach
Mechanical Engineering
ISBN:9781259822674
Author:Yunus A. Cengel Dr., Michael A. Boles
Publisher:McGraw-Hill Education
Control Systems Engineering
Mechanical Engineering
ISBN:9781118170519
Author:Norman S. Nise
Publisher:WILEY
Mechanics of Materials (MindTap Course List)
Mechanical Engineering
ISBN:9781337093347
Author:Barry J. Goodno, James M. Gere
Publisher:Cengage Learning
Engineering Mechanics: Statics
Mechanical Engineering
ISBN:9781118807330
Author:James L. Meriam, L. G. Kraige, J. N. Bolton
Publisher:WILEY
Understanding Conduction and the Heat Equation; Author: The Efficient Engineer;https://www.youtube.com/watch?v=6jQsLAqrZGQ;License: Standard youtube license