Thermodynamics: An Engineering Approach
8th Edition
ISBN: 9780073398174
Author: Yunus A. Cengel Dr., Michael A. Boles
Publisher: McGraw-Hill Education
expand_more
expand_more
format_list_bulleted
Concept explainers
Videos
Question
Chapter 2.8, Problem 94P
To determine
The temperature of the outer surface.
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solution
Students have asked these similar questions
3. A 2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic
cover whose thermal conductivity is k = 0.15 W/m· °C. Electrical measurements indicate
that a current of 10 A passes through the wire and there is a voltage drop of 8 V along the
wire. If the insulated wire is exposed to a medium at T = 30°C with a heat transfer coefficient
of h = 24 W/m2 · °C, determine the temperature at the interface of the wire and the plastic
cover in steady operation. Also determine if doubling the thickness of the plastic cover will
increase or decrease this interface temperature.
T = 30°C
Electrical
wire
Insulation
3-26 Consider a person standing in a room at 20°C with an
exposed surface area of 1.7 m². The deep body temperature of
the human body is 37°C, and the thermal conductivity of the
human tissue near the skin is about 0.3 W/m · °C. The body is
losing heat at a rate of 150 W by natural convection and radia-
tion to the surroundings. Taking the body temperature 0.5 cm
beneath the skin to be 37°C, determine the skin temperature of
the person.
Question 1:
Consider a 0.8-m-high and 1.5-m-wide double-pane window consisting of two 4-mm-thick layers of glass (k 0.78 W/m · °C) separated by a 10-mm-wide stagnant air space (k 0.026 W/m · °C). Determine the steady rate of heat transfer through this double-pane window and the temperature of its inner surface for a day during which the room is maintained at 20°C while the temperature of the outdoors is 10°C. Take the convection heat transfer coefficients on the inner and outer surfaces of the window to be h1 10 W/m2 · °C and h2 40 W/m2 · °C, which includes the effects of radiation.
Chapter 2 Solutions
Thermodynamics: An Engineering Approach
Ch. 2.8 - What is total energy? Identify the different forms...Ch. 2.8 - List the forms of energy that contribute to the...Ch. 2.8 - How are heat, internal energy, and thermal energy...Ch. 2.8 - What is mechanical energy? How does it differ from...Ch. 2.8 - Natural gas, which is mostly methane CH4, is a...Ch. 2.8 - Portable electric heaters are commonly used to...Ch. 2.8 - Prob. 7PCh. 2.8 - Prob. 8PCh. 2.8 - 2–9E Calculate the total potential energy, in Btu,...Ch. 2.8 - Prob. 10P
Ch. 2.8 - Prob. 11PCh. 2.8 - At a certain location, wind is blowing steadily at...Ch. 2.8 - A water jet that leaves a nozzle at 60 m/s at a...Ch. 2.8 - Prob. 14PCh. 2.8 - Prob. 15PCh. 2.8 - Consider a river flowing toward a lake at an...Ch. 2.8 - When is the energy crossing the boundaries of a...Ch. 2.8 - Consider an automobile traveling at a constant...Ch. 2.8 - A gas in a pistoncylinder device is compressed,...Ch. 2.8 - A room is heated by an iron that is left plugged...Ch. 2.8 - A room is heated as a result of solar radiation...Ch. 2.8 - Prob. 23PCh. 2.8 - A small electrical motor produces 5 W of...Ch. 2.8 - Prob. 25PCh. 2.8 - 2–26C Lifting a weight to a height of 20 m takes...Ch. 2.8 - Prob. 27PCh. 2.8 - Prob. 28PCh. 2.8 - Prob. 29PCh. 2.8 - Prob. 30PCh. 2.8 - Prob. 31PCh. 2.8 - Prob. 32PCh. 2.8 - Prob. 33PCh. 2.8 - A ski lift has a one-way length of 1 km and a...Ch. 2.8 - The engine of a 1500-kg automobile has a power...Ch. 2.8 - Prob. 36PCh. 2.8 - What are the different mechanisms for transferring...Ch. 2.8 - On a hot summer day, a student turns his fan on...Ch. 2.8 - Prob. 39PCh. 2.8 - A vertical pistoncylinder device contains water...Ch. 2.8 - At winter design conditions, a house is projected...Ch. 2.8 - A water pump increases the water pressure from 15...Ch. 2.8 - Prob. 43PCh. 2.8 - Prob. 44PCh. 2.8 - A university campus has 200 classrooms and 400...Ch. 2.8 - Prob. 46PCh. 2.8 - Consider a room that is initially at the outdoor...Ch. 2.8 - Prob. 48PCh. 2.8 - 2-49 The 60-W fan of a central heating system is...Ch. 2.8 - Prob. 50PCh. 2.8 - An escalator in a shopping center is designed to...Ch. 2.8 - Prob. 52PCh. 2.8 - How is the combined pumpmotor efficiency of a pump...Ch. 2.8 - Prob. 54PCh. 2.8 - Can the combined turbinegenerator efficiency be...Ch. 2.8 - Consider a 2.4-kW hooded electric open burner in...Ch. 2.8 - Prob. 57PCh. 2.8 - Prob. 58PCh. 2.8 - Prob. 59PCh. 2.8 - A geothermal pump is used to pump brine whose...Ch. 2.8 - Prob. 62PCh. 2.8 - Prob. 63PCh. 2.8 - The water in a large lake is to be used to...Ch. 2.8 - A 7-hp (shaft) pump is used to raise water to an...Ch. 2.8 - At a certain location, wind is blowing steadily at...Ch. 2.8 - Reconsider Prob. 265. Using appropriate software,...Ch. 2.8 - Water is pumped from a lake to a storage tank 15 m...Ch. 2.8 - Prob. 69PCh. 2.8 - A hydraulic turbine has 85 m of elevation...Ch. 2.8 - Prob. 71PCh. 2.8 - Water is pumped from a lower reservoir to a higher...Ch. 2.8 - Prob. 73PCh. 2.8 - An oil pump is drawing 44 kW of electric power...Ch. 2.8 - How does energy conversion affect the environment?...Ch. 2.8 - What is acid rain? Why is it called a rain? How do...Ch. 2.8 - Why is carbon monoxide a dangerous air pollutant?...Ch. 2.8 - What is the greenhouse effect? How does the excess...Ch. 2.8 - What is smog? What does it consist of? How does...Ch. 2.8 - Prob. 80PCh. 2.8 - Consider a household that uses 14,000 kWh of...Ch. 2.8 - When a hydrocarbon fuel is burned, almost all of...Ch. 2.8 - Prob. 83PCh. 2.8 - A typical car driven 20,000 km a year emits to the...Ch. 2.8 - What are the mechanisms of heat transfer?Ch. 2.8 - Which is a better heat conductor, diamond or...Ch. 2.8 - How does forced convection differ from natural...Ch. 2.8 - What is a blackbody? How do real bodies differ...Ch. 2.8 - Define emissivity and absorptivity. What is...Ch. 2.8 - Does any of the energy of the sun reach the earth...Ch. 2.8 - The inner and outer surfaces of a 5-m 6-m brick...Ch. 2.8 - The inner and outer surfaces of a 0.5-cm-thick 2-m...Ch. 2.8 - Reconsider Prob. 292. Using appropriate software,...Ch. 2.8 - Prob. 94PCh. 2.8 - Prob. 95PCh. 2.8 - Prob. 96PCh. 2.8 - Prob. 97PCh. 2.8 - For heat transfer purposes, a standing man can be...Ch. 2.8 - Prob. 99PCh. 2.8 - Prob. 100PCh. 2.8 - A 1000-W iron is left on the ironing board with...Ch. 2.8 - A 7-cm-external-diameter, 18-m-long hot-water pipe...Ch. 2.8 - A thin metal plate is insulated on the back and...Ch. 2.8 - Reconsider Prob. 2103. Using appropriate software,...Ch. 2.8 - The outer surface of a spacecraft in space has an...Ch. 2.8 - Prob. 106PCh. 2.8 - A hollow spherical iron container whose outer...Ch. 2.8 - Consider a vertical elevator whose cabin has a...Ch. 2.8 - Consider a homeowner who is replacing his...Ch. 2.8 - Prob. 110RPCh. 2.8 - Prob. 111RPCh. 2.8 - Prob. 112RPCh. 2.8 - 2–113 The U.S. Department of Energy estimates that...Ch. 2.8 - Prob. 114RPCh. 2.8 - Prob. 115RPCh. 2.8 - Prob. 116RPCh. 2.8 - Prob. 117RPCh. 2.8 - Consider a TV set that consumes 120 W of electric...Ch. 2.8 - Water is pumped from a 200-ft-deep well into a...Ch. 2.8 - Prob. 120RPCh. 2.8 - Prob. 121RPCh. 2.8 - In a hydroelectric power plant, 65 m3/s of water...Ch. 2.8 - The demand for electric power is usually much...Ch. 2.8 - The pump of a water distribution system is powered...Ch. 2.8 - On a hot summer day, the air in a well-sealed room...Ch. 2.8 - Prob. 126FEPCh. 2.8 - A 2-kW electric resistance heater in a room is...Ch. 2.8 - A 900-kg car cruising at a constant speed of 60...Ch. 2.8 - Prob. 129FEPCh. 2.8 - Prob. 130FEPCh. 2.8 - Prob. 131FEPCh. 2.8 - A 2-kW pump is used to pump kerosene ( = 0.820...Ch. 2.8 - Prob. 133FEPCh. 2.8 - Prob. 134FEPCh. 2.8 - Prob. 135FEPCh. 2.8 - Prob. 136FEPCh. 2.8 - Prob. 137FEPCh. 2.8 - Heat is transferred steadily through a...Ch. 2.8 - The roof of an electrically heated house is 7 m...
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
- Question 1 Consider a large plane wall of thickness L = 0.4 m, thermal conductivity k = 2.3 W/m · °C, and surface area A = 20 m². The left side of the wall is maintained at a constant temperature of T1 = 90°C while the right side loses heat by convection to the surrounding air at To = 25°C with a heat transfer coefficient of h = 40 W/m? · °C. Assuming constant thermal conductivity and no heat generation in the wall: (a) Express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the wall. (b) Obtain a relation for the variation of temperature in the wall by solving the differential equation. (c) Evaluate the rate of heat transfer through the wall.arrow_forwardThe interior of a refrigerator has a surface area of 6.2 m2. It is insulated by a 2 cm thick material that has a thermal conductivity of 0.0199 J/m·s • C. The ratio of the heat extracted from the interior to the work done by the motor is 5.5 % of the theoretical maximum. The temperature of the room is 27.6 •C, and the temperature inside the refrigerator is 6.6 •C. Determine the power required to run the compressor. Answer in units of W.arrow_forwardAn aluminum plate, with dimensions of 3 cm × 3 cm × 5 cm (length, width, and thickness, respectively), is exposed to a thermal energy source that puts out 150 J every second. The density of aluminum is 2700 kg⁄m3 . Assuming no heat loss to the surrounding block, determine the temperature rise in the plate after 10 seconds.arrow_forward
- Question 2: Consider a 0.8-m-high and 1.5-m-wide glass window with a thickness of 8 mm and a thermal conductivity of k 0.78 W/m · °C. Determine the steady rate of heat transfer through this glass window and the temperature of its inner surface for a day during which the room is maintained at 20°C while the temperature of the outdoors is 10°C. Take the heat transfer coefficients on the inner and outer surfaces of the window to be h1 10 W/m2 · °C and h2 40 W/m2 · °C, which includes the effects of radiation.arrow_forwardA wall with a thermal conductivity of 0.4 W/m-°C is maintained at 45°C. The heat transfer through the wall is 220 W. The wall surface area is 2.0m² and its thickness is 1.5 cm. Determine the temperature at the other surface.arrow_forward2-102 A long homogeneous resistance wire of radius r = 0.6 cm and thermal conductivity k 15.2 W/m-K is being used to boil water at atmospheric pressure by the passage of electric current. Heat is generated in the wire uniformly as a result of resistance heating at a rate of 16.4 W/cm3. The heat generated is transferred to water at 100°C by convection with an average heat transfer coefficient of h 3200 W/m2-K. Assuming steady one-dimensional heat transfer, (a) express the differential equation and the boundary conditions for heat conduction through the wire, (b) obtain a relation for the variation of temperature in the wire by solving the differential equation, and (c) determine the temperature at the centerline of the wire. Answer: () 125°C FIGURE P2-102 т. Water Resistance heaterarrow_forward
- 6. A cylindrical electric heater of outside diameter D = 2.5 cm and length L= 2 m is immersed horizontally into a pool of mercury at 100°C. If the surface of the heater is maintained at an average temperature of 300°C, calculate the rate of heat transfer to the mercury.arrow_forwardA hot surface at 100°C is to be cooled by attaching 3-cm-long, 0.25-cm-diameter copper pin fins (k 386 W /m · °C) to it, with a center-to-center distance of 0.6 cm. The temperature of the surrounding medium is 30°C, and the heat transfer coefficient on the surfaces is 35 W /m2 . °C. Determine the rate of heat transfer from the surface for a 1m x 1m section of the plate. Also determine the overall effectiveness of the fins. 3 cm D=0.25 cm 0.6 cmarrow_forwardA 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.arrow_forward
- A 50-m-long section of a steam pipe whose outer diameter is 10 cm passes through an open space at 15°C. The average temperature of the outer surface of the pipe is measured to be 150°C. If the combined heat transfer coefficient on the outer surface of the pipe is 20 W/m2-°C, determine the annual cost of this energy lost if steam is generated in a natural gas furnace that has an efficiency of 75 percent and the price of is $0.52/therm (1 therm natural gas 105,500 kJ) $|arrow_forwardConsider a person standing in a room at 23°C. Determine the total rate of heat transfer from this person if the exposed surface area and the skin temperature of the person arel.7 m2 and 32°C, respectively, and the convection heat transfer coefficient is 5 W/m2· °C. Take the emissivity of the skin and the clothes to be 0.9, and assume the temperature of the inner surfaces of the room to be the same as the air temperature.arrow_forwardQ:A hot surface at 100°C is to be cooled by attach- ing 3-cm-long, 0.25-cm-diameter aluminum pin fins (k 237 W/m · °C) to it, with a center-to-center distançe of 0.6 cm. The temperature of the surrounding medium is 30°C, and the heat transfer coefficient on the surfaces is 35 W/m2 . °C. Determine the rate of heat transfer from the surface for a 1-m X 1-m section of the plate. Also determine the overall effectiveners of the fins. Ans. Q=17.4 kW , E fin = 7.1 3 cm 0.6 cm L0.25 cmarrow_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
8.01x - Lect 27 - Fluid Mechanics, Hydrostatics, Pascal's Principle, Atmosph. Pressure; Author: Lectures by Walter Lewin. They will make you ♥ Physics.;https://www.youtube.com/watch?v=O_HQklhIlwQ;License: Standard YouTube License, CC-BY
Dynamics of Fluid Flow - Introduction; Author: Tutorials Point (India) Ltd.;https://www.youtube.com/watch?v=djx9jlkYAt4;License: Standard Youtube License