Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
8th Edition
ISBN: 9781305387102
Author: Kreith, Frank; Manglik, Raj M.
Publisher: Cengage Learning
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Textbook Question
Chapter 1, Problem 1.4P
To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus shown in the accompanying sketch. Electric current is supplied to the
Problem 1.4
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The temperature at the inside surface of an oven is 460 oF. The inside wall of the oven is made of brick and is 8 inch thick. The thermal conductivity of the brick is 2.2 Btu/hr.ft2.(oF/ft). The outside of the oven is covered with a 3-inch layer of asbestos as insulation, which has a thermal conductivity of 0.11 Btu/hr.ft2.(oF/ft). If the outer surface of the insulation has a temperature of 100 oF , calculate the amount of heat lost through 2 ft2 of wall area in 3 hours.
Question 5: A copper bar 35 cm long, with square cross-section 2 cm x 2 cm is fitted with a
resistive heater at one end, and a large heat sink at the other. The bar itself is ideally thermally
lagged.
(i)
(ii)
Sketch how you think the two thermometers would behave when the heater is switched
on;
(ii) Calculate the thermal conductivity if in the steady-state, T1=64.7 deg C and T2=40.0
deg C.
Hint: rate of flow of heat = k*A*AT/X
V=6 V,
I=2.5A
heater
T1
25 cm
T2
Heat
sink
A rectangular electrical heater is attached to a metal sheet. Measurements show the surface temperatures of T1, T2, T3 are 55, 60 and 42 °C, respectively. Both sides of the heater and metal sheet are exposed to an environment where h is equal, and T∞ = 23 °C. Assume K values & you can neglect the contact resistance. a. Find the value of h.b. Find the value of the volumetric heat generation.c. Draw the sketch of the temperature as a function of the direction of heat dissipation.d. What is the exact location of the maximum temperature in the plate-heater assembly?e. If h = 230 W/m2K, q_dot = 1 x 103 W/m3, what is the maximum temperature in the heater?
Chapter 1 Solutions
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
Ch. 1 - 1.1 On a cold winter day, the outer surface of a...Ch. 1 - 1.2 The weight of the insulation in a spacecraft...Ch. 1 - 1.3 A furnace wall is to be constructed of brick...Ch. 1 - 1.4 To measure thermal conductivity, two similar...Ch. 1 - To determine the thermal conductivity of a...Ch. 1 - A square silicon chip 7mm7mm in size and 0.5-mm...Ch. 1 - A cooling system is to be designed for a food...Ch. 1 - 1.80 Describe and compare the modes of heat loss...Ch. 1 - Heat is transferred at a rate of 0.1 kW through...Ch. 1 - 1.10 A heat flux meter at the outer (cold) wall of...
Ch. 1 - 1.11 Calculate the heat loss through a glass...Ch. 1 - 1.12 A wall with a thickness is made of a...Ch. 1 - 1.13 If the outer air temperature in Problem is...Ch. 1 - Using Table 1.4 as a guide, prepare a similar...Ch. 1 - 1.15 A thermocouple (0.8-mm-diameter wire) used to...Ch. 1 - Water at a temperature of 77C is to be evaporated...Ch. 1 - The heat transfer rate from hot air by convection...Ch. 1 - The heat transfer coefficient for a gas flowing...Ch. 1 - 1.19 A cryogenic fluid is stored in a...Ch. 1 - A high-speed computer is located in a...Ch. 1 - 1.21 In an experimental set up in a laboratory, a...Ch. 1 - 1.22 In order to prevent frostbite to skiers on...Ch. 1 - Using the information in Problem 1.22, estimate...Ch. 1 - Two large parallel plates with surface conditions...Ch. 1 - 1.25 A spherical vessel, 0.3 m in diameter, is...Ch. 1 - 1.26 Repeat Problem 1.25 but assume that the...Ch. 1 - Determine the rate of radiant heat emission in...Ch. 1 - 1.28 The sun has a radius of and approximates a...Ch. 1 - 1.29 A spherical interplanetary probe with a 30-cm...Ch. 1 - A spherical communications satellite, 2 m in...Ch. 1 - A long wire 0.7 mm in diameter with an emissivity...Ch. 1 - Wearing layers of clothing in cold weather is...Ch. 1 - A section of a composite wall with the dimensions...Ch. 1 - A section of a composite wall with the dimensions...Ch. 1 - Repeat Problem 1.35 but assume that instead of...Ch. 1 - 1.37 Mild steel nails were driven through a solid...Ch. 1 - Prob. 1.38PCh. 1 - 1.39 On a cold winter day, the outside wall of a...Ch. 1 - As a designer working for a major electric...Ch. 1 - 1.41 A heat exchanger wall consists of a copper...Ch. 1 - 1.43 A simple solar heater consists of a flat...Ch. 1 - A composite refrigerator wall is composed of 5 cm...Ch. 1 - An electronic device that internally generates 600...Ch. 1 - 1.47 A flat roof is modeled as a flat plate...Ch. 1 - A horizontal, 3-mm-thick flat-copper plate, 1-m...Ch. 1 - 1.49 A small oven with a surface area of is...Ch. 1 - A steam pipe 200 mm in diameter passes through a...Ch. 1 - 1.51 The inner wall of a rocket motor combustion...Ch. 1 - 1.52 A flat roof of a house absorbs a solar...Ch. 1 - Determine the power requirement of a soldering...Ch. 1 - 1.54 The soldering iron tip in Problem 1.53...Ch. 1 - Prob. 1.55PCh. 1 - A pipe carrying superheated steam in a basement at...Ch. 1 - Draw the thermal circuit for heat transfer through...Ch. 1 - 1.60 Two electric resistance heaters with a 20 cm...Ch. 1 - 1.63 Liquid oxygen (LOX) for the space shuttle is...Ch. 1 - The interior wall of a large, commercial walk-in...Ch. 1 - 1.67 In beauty salons and in homes, a ubiquitous...Ch. 1 - The heat transfer coefficient between a surface...Ch. 1 - The thermal conductivity of fibreglass insulation...Ch. 1 - 1.71 The thermal conductivity of silver at 212°F...Ch. 1 - 1.72 An ice chest (see sketch) is to constructed...Ch. 1 - Estimate the R-values for a 5-cm-thick fiberglass...Ch. 1 - A manufacturer in the United States wants to sell...Ch. 1 - Referring to Problem 1.74, how many kilograms of...Ch. 1 - 1.76 Explain a fundamental characteristic that...Ch. 1 - 1.77 Explain each in your own words. (a) What is...Ch. 1 - What are the important modes of heat transfer for...Ch. 1 - 1.79 Consider the cooling of (a) a personal...Ch. 1 - Describe and compare the modes of heat loss...Ch. 1 - A person wearing a heavy parka is standing in a...Ch. 1 - Discuss the modes of heat transfer that determine...
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- Determine the thermal conductivity of water vapor at 174°C.arrow_forwardMr. Bane is observing a protrude fin with a thickness of 0.0295 inches with a thermal conductivity of 75 SI unit. He also noticed that it protrude 0.984 inches from a cylindrical surface of 0.050 m diameter and 3.28 ft length which was exposed in an atmosphere having a 40°C. If the cylindrical surface is maintained at 150°C and the heat transfer coefficient is 23 SI units, calculate the rate of heat transfer. A 1189.4 W 1003.4 W 358.4 W D 2035.4 W E 1670.4 W F None of thesearrow_forwardMr. Bane is observing a protrude fin with a thickness of 0.0295 inches with a thermal conductivity of 75 SI unit. He also noticed that it protrude 0.984 inches from a cylindrical surface of 0.050 m diameter and 3.28 ft length which was exposed in an atmosphere having a 40°C. If the cylindrical surface is maintained at 150°C and the heat transfer coefficient is 23 SI units, calculate the rate of heat transfer. A 1189.4 W B 1003.4 W (c) 358.4 W 2035.4 W E 1670.4 W F) None of thesearrow_forward
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