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
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 1, Problem 1.10P
A heat flux meter at the outer (cold) wall of a concrete building indicates that the heat loss through a wall of 10-cm thickness is
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
Q2 fin made of AL metal with thermal conductivity (199 W / mK). Fin dimensions 3 cm long and 2.5 mm thick, extending from a wall and exposed to air at the end. Wall temperature 420 ° C and air temperature 25 ° C. Calculate the heat loss from the fin and the fin efficiency. Assume the heat transfer coefficient of 10 W / m K and neglect the heat loss at the fin tip. Explain the importance of assuming isolated n fin end in practice
Stainless steel pipes with a thermal conductivity of 17 W/ (m° C) are used to transport hot
oil. The temperature inside the tube is 130 ° C. The inner diameter of the pipe is 8 cm and
the thickness of the pipe wall is 2 cm. The pipe is then insulated with 4 cm thick insulation
with a thermal conductivity of 0.035 W / (m° C). The ambient temperature of the pipe is 25
° C. Calculate the temperature between the steel and the insulation if we assume a steady
state. A picture of the pipe can be seen below.
2. A refrigerated cold room wall has a thickness of 100mm and a thermal conductivity
0.14 W/m-K. The room wall has a 60mm thick internal lining of cork having a thermal
conductivity of 0.05 W/m.K. The thermal conductance between the exposed faces and
the respective atmosphere is 12 W/m²-K.
If the room is maintained at 0°C and the external atmospheric temperature is
20°C, Calculate the heat loss rate through 1m² of the wall.
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...
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
- 2.38 The addition of aluminum fins has been suggested to increase the rate of heat dissipation from one side of an electronic device 1 m wide and 1 m tall. The fins are to be rectangular in cross section, 2.5 cm long and 0.25 cm thick, as shown in the figure. There are to be 100 fins per meter. The convection heat transfer coefficient, both for the wall and the fins, is estimated to be K. With this information determine the percent increase in the rate of heat transfer of the finned wall compared to the bare wall.arrow_forward1.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that passes through the nails when the temperature difference across the wall is 25°C. Neglect contact resistance between the wood layers.arrow_forward1.1 On a cold winter day, the outer surface of a 0.2-m-thick concrete wall of a warehouse is exposed to temperature of –5°C, while the inner surface is kept at 20°C. The thermal conductivity of the concrete is 1.2 W/m K. Determine the heat loss through the wall, which is 10-m long and 3-m high. Problem 1.1arrow_forward
- 3.16 A large, 2.54-cm.-thick copper plate is placed between two air streams. The heat transfer coefficient on one side is and on the other side is . If the temperature of both streams is suddenly changed from 38°C to 93°C, determine how long it takes for the copper plate to reach a temperature of 82°C.arrow_forward2.30 An electrical heater capable of generating 10,000 W is to be designed. The heating element is to be a stainless steel wire having an electrical resistivity of ohm-centimeter. The operating temperature of the stainless steel is to be no more than 1260°C. The heat transfer coefficient at the outer surface is expected to be no less than in a medium whose maximum temperature is 93°C. A transformer capable of delivering current at 9 and 12 V is available. Determine a suitable size for the wire, the current required, and discuss what effect a reduction in the heat transfer coefficient would have. (Hint: Demonstrate first that the temperature drop between the center and the surface of the wire is independent of the wire diameter, and determine its value.)arrow_forwardA high-speed computer is located in a temperature-controlled room at 26C. When the machine is operating, its internal heat generation rate is estimated to be 800 W. The external surface temperature of the computer is to be maintained below 85C. The heat transfer coefficient for the surface of the computer is estimated to be 10W/m2K. What surface area would be necessary to assure safe operation of this machine? Comment on ways to reduce this area.arrow_forward
- Calculate the rate of heat loss through the vertical walls of a boiler furnace of size 4 m by 3 m by 3 m high. The walls are constructed from an inner fire brick wall 25 cm thick of thermal conductivity 0.4 W/mK. The inside temperature of the fire brick layer was measured at 600 C and the temperature of the outside was 60 C.arrow_forwardThe exterior wall of a house is composed of a 20 cm thick layer of ordinary brick (conductivity 0.72 W/m K) and a 2.5 cm layer of plaster (conductivity 0.17 W/m K ) on each side (two layers in total). Other purely conductive resistances can be neglected, such as the layer of paint on both sides of the wall. Assume the outer face of the wall is at 35 °C and the inner face is at 20 °C and fill in the gaps. The magnitude of the heat flux through the wall corresponds to the _________ W/m2 and is perpendicular to the wall ________________(fill in with "outside-in" or "inside-out") of the environment. If the wall has a total area of 300m2, the heat transfer rate corresponds to ___________________arrow_forwarda flat wall is covered with a layer of insulation 1.0 in. thick whose thermal conductivity is 0.8 Btu/hr-ft- F. the temperature of the wall on the inside of the insulation is 600F. the wall loses heat to the environment by convection on the surface of the insulation. the average value of the convection heat transfer coefficient on the inslation surface is 950 Btu/hr-ft^2-F. compute the bulk temperature of the environment if the outer surface of the insulation does not exceed 105 F.arrow_forward
- Calculate the rate of heat loss through the vertical walls of a boiler furnace of size 4 m by 3 m by 3 m high. The walls are constructed from an inner fire brick wall of 20 cm thick with thermal conductivity 0.4 W/mK, a layer of ceramic blanket insulation with thermal conductivity of 0.2 W/mK and 10 cm thick, and a steel protective layer with thermal conductivity of 55 W/mK and 3 mm thick. The inside temperature of the fire brick layer was measured at 600°C and the temperature of the outside of the insulation was 60°C. Also find the interface temperature of layers.arrow_forwardAn oil flow through a 40 mm bore steel pipe with the thickness of 4 mm. The pipe is covered by 10 mm thickness of insulator with the thermal conductivity of 0.038 W/m.K as shown in Diagram 4b. The temperature of the oil in the pipe is 75°C and the ambient temperature is 17°C. The internal thermal conductivity of steel is 50 W/m.K and the inside and outside heat transfer coefficient are 300 W/m².C and 17 W/m?.C respectively. Neglecting radiation, calculate the following: i. Rate of heat flow per meter length of the pipe ii. The temperature of the outside surface (Ts). Ts Ambient Oil 75°C temperature 17°C 40 Note : All dimensions are in mm/Nota: Semua dimensi adalah dalam mm Diagram 4b/Rajah 4barrow_forward4. 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. Tair = 30°C Electrical wire Insulation 10 marrow_forward
arrow_back_ios
SEE MORE QUESTIONS
arrow_forward_ios
Recommended textbooks for you
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
Principles of Heat Transfer (Activate Learning wi...
Mechanical Engineering
ISBN:9781305387102
Author:Kreith, Frank; Manglik, Raj M.
Publisher:Cengage Learning
Understanding Conduction and the Heat Equation; Author: The Efficient Engineer;https://www.youtube.com/watch?v=6jQsLAqrZGQ;License: Standard youtube license