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
Videos
Textbook Question
Chapter 1, Problem 1.40P
As a designer working for a major electric appliance manufacturer, you are required to estimate the amount of fiberglass insulation packing (k = 0.035 W/m K) that is needed for a kitchen oven shown in the figure below. The fiberglass layer is to be sandwiched
between a 2-mm-thick aluminum cladding plate on the outside and a 5-mm-thick stainless steel plate on the inside that forms the core of the oven. The insulation thickness is such that the outside cladding temperature does not exceed
Expert Solution & Answer
Trending nowThis is a popular solution!
Students have asked these similar questions
3.6
Heat losses through windows in buildings are substantial. What would be the percentage reduction in heat loss that would be mitigated by replacing a window containing a single pane of glass with (a) double-pane low-E insulating glass or (b) a 3-inch-thick sheet of expanded polystyrene sheet? The quoted R values for these items are: • single pane of glass: 0.90 ft 2 hr ° F/Btu, • double pane of low-E insulating glass: 2.3 ft 2 hr ° F/Btu, • 1-inch-thick sheet of polystyrene sheet: 4.0 ft 2 hr ° F/Btu.
Q2 a) A leading manufacturer of household appliances is proposing a self-cleaning oven
design that involves use of a composite window separating the oven cavity from the
room air (Figure 2a). The composite is to consist of two high-temperature plastics
(A and B) of thicknesses LA = 2LB and thermal conductivities ka = 0.15 W/m·K and
kB = 0.08 W/m•K. During the self-cleaning process, the oven wall and air
temperatures, Tw and Ta, are 400°C, while the room air temperature To is 25°C. The
inside convection and radiation heat transfer coefficients h; and h,, as well as the
outside convection coefficient ho, are each approximately 25 W/m².K. What is the
minimum window thickness, L = LA + LB, needed to ensure a temperature that is
50°C or less at the outer surface of the window? This temperature must not be
exceeded for safety reasons.
Pravinbhai
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
- 20-m pipe has an outside diameter of 50 mm. Pipe is insulated with a layer of asbestos, then followed by a layer of cork. Inside and outside diameter of the cork is 77 mm and 80 mm, respectively. If the temperature drop from pipe to cork is 1165°C, calculate the inside diameter of the pipe (mm). The rate of the heat transfer is 8778 W. The thermal conductivity of steam pipe, asbestos and cork are 0.045 kW/m-K, 0.058 W/m-K and 0.043 W/m-K respectively.arrow_forward(b) A hydrogen gas cylinder is situated in the cylinder cage. The cylinder wall is constructed from 15.5 mm carbon fiber (kcp = 0.75 W mK-¹). The outside of the cylinder is lagged with an inner 10 mm layer of ceramic insulation (kc = 0.08 W mK-¹) and an outer 80 mm layer of fiberglass insulation (kp = 0.15 W mK-¹). The temperature on the hydrogen gas is 150 °C and the temperature of the cylinder cage is 45 °C. Given that the walls of the cylinder can be assumed to be flat and neglecting the contribution of radiation, calculate: (i) the heat flux per square meter of the gas cylinder wall (ii) the temperature at the interface between the fibreglass and the ceramic insulation. 1.1arrow_forwardA dormitory at a large university, built 50 years ago, has exterior walls constructed of L, = 25-mm-thick sheathing with a thermal conductivity of k, = 0.1 W/m-K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by applying an L; = 25-mm-thick layer of extruded insulation characterized by k; = 0.029 W/m-K to the exterior of the original sheathing. The extruded insulation is, in turn, covered with an Lg = 5-mm-thick architectural glass with kg = 1.4 W/m-K. Determine the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are Ti = 22°C and T.0 -17.5°C, respectively. The inner and outer convection heat transfer coefficients are h; = 5W/m?-K and h, = 25 W/m²-K, respectively. The heat flux through the original walls is i W/m?. The heat flux through the retrofitted walls is i W/m?.arrow_forward
- A dormitory at a large university, built 50 years ago, has exterior walls constructed of L, = 25-mm-thick sheathing with a thermal conductivity of k, = 0.1 W/m-K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by applying an L; = 25-mm-thick layer of extruded insulation characterized by k; = 0.029 W/m-K to the exterior of the original sheathing. The extruded insulation is, in turn, covered with an L, = 5-mm-thick architectural glass with kg = 1.4 W/m-K. Determine the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are Ti = 22°C and T0 -15°C, respectively. The inner and outer convection heat transfer coefficients are h; = 5 W/m?-K and h, = 25 W/m²-K, respectively. The heat flux through the original walls is i W/m?. The heat flux through the retrofitted walls is i W/m?.arrow_forwardA 1.69 m wide by 1.06 m high metal plate must be insulated to prevent contact burn injuries. If the heat transfer rate is 131 W and the temperature across the insulation must be reduced from 87.9°C to 40.2°C, what is the minimum thickness (in cm) of insulation required [round your final answer to two decimal places]? {kins = 0.033 W/m∙K}arrow_forward[2] An array of electronic chips is mounted within a sealed rectangular enclosure, and cooling is implemented by attaching an aluminum heat sink (k = 180 W/m K). The base of the heat sink has dimensions of w1 = W2 = 100 mm, while the 6 fins are of thickness t = 10 mm and pitch S = 18 mm. The fin length is Lr = 50 mm, and the base of the heat sink has a thickness of Lb = 10 mm. L -Chips Water u T Electronic package, P elec If cooling is implemented by water flow through the heat sink, with uo = 3 m/s and To = temperature Tb of the heat sink when power dissipation by the chips is Pelec = 1800 W? The average convection coefficient for surfaces of the fins and the exposed base may be estimated by assuming parallel flow over a flat plate. Properties of the water may be approximated as k = 0.62 W/m-K, p = 995 kg/m3, Cp = 4178 J/kg-K, v = 7.73 x 10-7 m2/s, and Pr = 5.2. 17°C, what is the base a.) Base temperature. А. 37.8°C B. 43.9°C С. 31.4°С D. 46.2°Carrow_forward
- Q2 a) A leading manufacturer of household appliances is proposing a self-cleaning oven design that involves use of a composite window separating the oven cavity from the room air (Figure 2a). The composite is to consist of two high-temperature plastics (A and B) of thicknesses LA = 2LB and thermal conductivities kA = 0.15 W/m K and kB = 0.08 W/m K. During the self-cleaning process, the oven wall and air temperatures, Tw and Ta, are 400°C, while the room air temperature T is 25°C. The inside convection and radiation heat transfer coefficients h and hr, as well as the outside convection coefficient ho, are each approximately 25 W/m2.K. What is the minimum window thickness, L = LA + LB, needed to ensure a temperature that is 50°C or less at the outer surface of the window? This temperature must not be exceeded for safety reasons.arrow_forwardX Your answer is incorrect. A dormitory at a large university, built 50 years ago, has exterior walls constructed of L, = 25-mm-thick sheathing with a thermal conductivity of k, = 0.1 W/m-K. To reduce heat losses in the winter, the university decides to encapsulate the entire dormitory by applying an L; = 25-mm-thick layer of extruded insulation characterized by k; = 0.029 W/m-K to the exterior of the original sheathing. The extruded insulation is, in turn, covered with an Lg = 5-mm-thick architectural glass with kg = 1.4 W/m-K. Determine the heat flux through the original and retrofitted walls when the interior and exterior air temperatures are T = 22°C and To = O°C, respectively. The inner and outer convection heat transfer coefficients are h; = 5 W/m?-Kand h, 00, 25 W/m2-K, respectively. The heat flux through the original walls is 1.46 W/m?. The heat flux through the retrofitted walls is 0.92 W/m?.arrow_forwardRequired info: There is a 2.00 cm thick stagnant air pocket. a) What thickness of cork would have the same R-factor as the stagnant air pocket? The thermal conductivity of air is 0.0230 W/m-K and of cork is 0.0460 W/m-K. b) What thickness of tin would be required for the same R-factor as a 2.00-cm-thick stagnant air pocket? The thermal conductivity of air is 0.0230 W/m:K and of tin is 66.8 W/m-K. THANK Uarrow_forward
- Kindly help me to answer this thankyouarrow_forwardA steel pipe (outside diameter 100 mm) is covered with two layers of insulation. The inside layer, 40 mm thick, has a thermal conductivity of 0.07 W/(m K). The outside layer, 20 mm thick, has a thermal conductivity of 0.15 W/(m K). The pipe is used to convey steam at a pressure of 600 kPa. The outside temperature of insulation is 24°C. If the pipe is 10 m long, determine the following, assuming the resistance to conductive heat transfer in steel pipe and convective resistance on the steam side are negligible: a. The heat loss per hour. b. The interface temperature of insulation.arrow_forward5. A pipe with an outside diameter of 2.5 inches is insulated with 2 inches layer of asbestos (k = 0.396 Btu- in/hr-ft²-°F), followed by a layer of cork 1.5 inches thick (k = 0.30 Btu-in/hr-ft²-°F). If the temperature at the inner surface of the pipe is 290°F and at the outer surface of the cork is 90°F, calculate the heat loss per 100 ft of insulated pipe. (Btu/hr)arrow_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