Introduction to Heat Transfer
6th Edition
ISBN: 9780470501962
Author: Frank P. Incropera, David P. DeWitt, Theodore L. Bergman, Adrienne S. Lavine
Publisher: Wiley, John & Sons, Incorporated
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Chapter 1, Problem 1.50P
The emissivity of galvanized steel sheet, a common roofing material, is
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The emissivity of galvanized steel sheet, a common roofing material, is ε = 0.13 at temperatures around 300 K, while its absorptivity for solar irradiation is αS = 0.65. Would the neighborhood cat be comfortable walking on a roof constructed of the material on a day when GS = 750 W/m2, T∞ = 16°C, and h = 7 W/m2 · K? Assume the bottom surface of the steel is insulated.
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Chapter 1 Solutions
Introduction to Heat Transfer
Ch. 1 - The thermal conductivity of a sheet of rigid,...Ch. 1 - The heat flux that is applied to the left face of...Ch. 1 - A concrete wall, which has a surface area of 20m2...Ch. 1 - The concrete slab of a basement is 11 m long, 8 m...Ch. 1 - Consider Figure 1.3. The heat flux in the...Ch. 1 - Prob. 1.6PCh. 1 - The inner and outer surface temperatures of a...Ch. 1 - A thermodynamic analysis of a proposed Brayton...Ch. 1 - A glass window of width W=1m and height H=2m is 5...Ch. 1 - Prob. 1.10P
Ch. 1 - The heat flux that is applied to one face of a...Ch. 1 - Prob. 1.12PCh. 1 - Prob. 1.13PCh. 1 - Prob. 1.14PCh. 1 - The 5-mm-thick bottom of a 200-mm-diameter pan may...Ch. 1 - Prob. 1.16PCh. 1 - For a boiling process such as shown in Figure...Ch. 1 - You've experienced convection cooling if you've...Ch. 1 - Prob. 1.19PCh. 1 - A wall has inner and outer surface temperatures of...Ch. 1 - An electric resistance heater is embedded in a...Ch. 1 - Prob. 1.22PCh. 1 - A transmission case measures W=0.30m on a side and...Ch. 1 - Prob. 1.24PCh. 1 - A common procedure for measuring the velocity of...Ch. 1 - Prob. 1.26PCh. 1 - Prob. 1.27PCh. 1 - Prob. 1.28PCh. 1 - Prob. 1.29PCh. 1 - Prob. 1.30PCh. 1 - Prob. 1.31PCh. 1 - Prob. 1.32PCh. 1 - Prob. 1.33PCh. 1 - Prob. 1.34PCh. 1 - An electrical resistor is connected to a battery,...Ch. 1 - Pressurized water pin=10bar,Tin=110C enters the...Ch. 1 - Consider the tube and inlet conditions of Problem...Ch. 1 - An internally reversible refrigerator has a...Ch. 1 - A household refrigerator operates with cold- and...Ch. 1 - Chips of width L=15mm on a side are mounted to a...Ch. 1 - Consider the transmission case of Problem 1.23,...Ch. 1 - One method for growing thin silicon sheets for...Ch. 1 - Heat is transferred by radiation and convection...Ch. 1 - Radioactive wastes are packed in a long,...Ch. 1 - An aluminum plate 4 mm thick is mounted in a...Ch. 1 - A blood warmer is to be used during the...Ch. 1 - Consider a carton of milk that is refrigerated at...Ch. 1 - The energy consumption associated with a home...Ch. 1 - Liquid oxygen, which hems a boiling point of 90 K...Ch. 1 - The emissivity of galvanized steel sheet, a common...Ch. 1 - Three electric resistance heaters of length...Ch. 1 - A hair dryer may be idealized as a circular duct...Ch. 1 - In one stage of an annealing process, 304...Ch. 1 - Convection ovens operate on the principle of...Ch. 1 - Annealing, an important step in semiconductor...Ch. 1 - In the thermal processing of semiconductor...Ch. 1 - A furnace for processing semiconductor materials...Ch. 1 - Single fuel cells such as the one of Example 1.5...Ch. 1 - Prob. 1.59PCh. 1 - Prob. 1.60PCh. 1 - Prob. 1.61PCh. 1 - A small sphere of reference-grade iron with a...Ch. 1 - A 50mm45mm20mm cell phone charger has a surface...Ch. 1 - A spherical, stainless steel (AISI 302) canister...Ch. 1 - Prob. 1.65PCh. 1 - Prob. 1.66PCh. 1 - A photovoltaic panel of dimension 2m4m is...Ch. 1 - Following the hot vacuum forming of a paper-pulp...Ch. 1 - Prob. 1.69PCh. 1 - Prob. 1.70PCh. 1 - Prob. 1.71PCh. 1 - The roof of a car in a parking lot absorbs a solar...Ch. 1 - Prob. 1.73PCh. 1 - Prob. 1.74PCh. 1 - Consider Problem 1.1. If the exposed cold surface...Ch. 1 - Prob. 1.76PCh. 1 - Prob. 1.77PCh. 1 - A thin electrical heating element provides a...Ch. 1 - Prob. 1.79PCh. 1 - Prob. 1.80PCh. 1 - Prob. 1.81PCh. 1 - The curing process of Example 1.9 involves...Ch. 1 - The diameter and surface emissivity of an...Ch. 1 - Bus bars proposed for use in a power transmission...Ch. 1 - A solar flux of 700W/m2 is incident on a...Ch. 1 - In considering the following problems involving...
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- 1.11 Calculate the heat loss through a glass window 7-mm thick if the inner surface temperature is 20°C and the outer surface temperature is 17°C. Comment on the possible effect of radiation on your answer.arrow_forward1.26 Repeat Problem 1.25 but assume that the surface of the storage vessel has an absorbance (equal to the emittance) of 0.1. Then determine the rate of evaporation of the liquid oxygen in kilograms per second and pounds per hour, assuming that convection can be neglected. The heat of vaporization of oxygen at –183°C is .arrow_forwardA furnace wall is constructed of an inner layer of 12.7 mm of refracter material, a middle layer of 101.6 mm of insulation material and outer layer of 76.2 mm of steel. The wall surface temperature is 1370 °C inside the refracter material (T0) and 37.8 °C at the outside surface of the steel (T3). Use thermal conductivity for refractor kref = 6.64 W/mK, for insulation, kins= 2.34 W/mK and for steel kste = 45 W/mK. Calculate the heat loss in W for 1 m2 (heat flux)? The temperature at the inter face between the insulation material and steel board?arrow_forward
- A flat-plate solar collector, as shown in Fig. 1, is used to heat water by having water flow through tubes attached at the back of the thin solar absorber plate. The absorber plate has an emissivity and an absorptivity of 0.8. The top surface (* = 0) temperature of the absorber is To = 35 °C, and solar radiat ion is incident on the absorber at 600 W/m? with a surrounding temperature of 0 °C. The convection heat transfer coefficient at the absorber surface as 8 W/m?-K. Assuming constant thermal conductivity and no heat generation in the wall, i express the differential equation and the boundary conditions for steady one- dimensional heat conduct ion through the wall, obtain a relation for the variation of temperature in the wall by solving the differential equation, and ii iii. determine the net heat flux, ġo absorbed by the collector ε, α, Τ. Absorber plate Water tubes Insulation Fig. 1arrow_forward2 inch OD during a visit to a plastic sheet factory 60 m long section of a horizontal steam pipe passes from one end to the other without insulation is observed. While the temperature of the ambient air and its surfaces is 20 °C, the temperature measurements at several points are the average of the exposed surfaces of the steam pipe. indicates that the temperature is 160 °C. It is seen that the outer surface of the pipe is oxidized and The emissivity can be taken as 0.59. According to this; a) Calculate the heat loss in the steam pipe. b) The steam used is produced in a gas furnace operating with an efficiency of 59%. Factory 105500 It pays $1.10 per kJ of natural gas. If it is assumed that the factory works all year (365 days), for this facility Calculate the annual cost of heat losses in the steam pipe.arrow_forwardA wood stove is used to heat a single room. The stove is cylindrical in shape, with a diameter of D = 0.400 m and a length of L = 0.500 m, and operates at a temperature of T, = 200 °C. (a) If the temperature of the room is T, = 20°C, determine the amount of radiant energy delivered to the room by the stove each second if the emissivity of the stove is e = 0.920. (b) By definition, the R-value of a conducting slab is given by Atot(Th – To) Poond R = where Atot is the total surface area, Pcond is the power loss by conduction through the slab, Th and Te are the temperatures on the hotter and cooler sides of the slab. If the room has a square shape with walls of height H = 2.40 m and width W = 7.60 m, determine the R-value of the walls and ceiling required to maintain the room temperature at T = 20°C if the outside temperature is T, = 0°C. Note that we are ignoring any heat conveyed by the stove via convection and any energy lost through the walls and windows via convection or radiation.arrow_forward
- A one-dimensional plane wall is exposed to convective and radiative conditions at x = 0. The ambient and surrounding temperatures are T = 15C and Tsur = 80C, respectively. The convection heat transfer coefficient is h = 40 W/(m2K) and the absorptivity of the exposed surface is = 0.8. Determine the convective and radiative heat fluxes to the wall at x = 0 in W/m2, if the wall surface temperature is 24C. Assume the exposed wall surface is gray (meaning = ) and the surroundings are much larger than the wall surface.arrow_forwardDetermine the heat transfer that occurs by radiation between two surfaces that are co-axial and parallel to each other, full and semicircular. Assume that the surfaces only exchange radiation with each other. T1 = 700 °C; ɛ1 = 0.8; T2 = 20 °C; e2 = 0.4. фб ст (2) to 4 cm 6 8 cm (1 t.arrow_forwardConsider a small house with walls 3.7 m high and each of four walls is 12.2 m long. A total of eight windows areplaced in these walls, each with dimensions 0.9 m by 1.2 m. The windows are single paned with k = 0.78 W/m∙K and0.6 cm thick. The walls have an RSI value of 3.4, which means they have RA = L/K = 3.4 m2K/W resisting heat flow.The heat transfer coefficients on the inside and outside of the house are 3 and 6 W/m2K, respectively. Whatpercentage of total heat loss leaves through the windows? Neglect radiative heat loss.arrow_forward
- A composite wall is comprised of two large plates separated by sheets of refractory insulation. In the installation process, the sheets of thickness L = 50 mm and thermal conductivity k = 0.05 W/mK are separated at 1-m intervals by gaps of width w = 10 mm. The hot and cold plates have temperatures and emissivities of T1 = 400 deg C, emissivity1 = 0.85 and T2 = 35 deg C, emissivity2 = 0.5, respectively. Assume that the plates and insulation are diffuse-gray surfaces. %3D Determine the heat loss by radiation through the gap per unit length of the composite wall (normal to the page). Recognizing that the gaps are located on a 1-m spacing, determine what fraction of the total heat loss through the composite wall is due to transfer by radiation through the insulation gap. Hot side Gap w = 10 mm A. 47 W/m, 9.2% T1 = 400°C B. 47 W/m, 10.2% L = 50 mm C. 37 W/m, 10.2% D. 37 W/m, 9.2% T2 = 35°C Cold side 1 m Insulation, k = 0.05 W/m-Karrow_forwardA one-dimensional plane wall is exposed to convective and radiative conditions at x = 0. The ambient and surrounding temperatures are T = 20°C and Tsur = 40°C, respectively. The convection heat transfer coefficient is h = 20 W/m².K, and the absorptivity of the exposed surface is a = 0.78. Determine the convective and radiative heat fluxes to the wall at x = 0, both in W/m², if the wall surface temperature is T = 25°C. Assume the exposed wall surface is gray, and the surroundings are large. q'conv i W/m² = grad = i W/m²arrow_forwardConsider a large plane wall of thickness L = 0.8 ft and thermal conductivity k = 1.2 Btu/h-ft-°F. The wall is covered with a material that has an emissivity of ε = 0.80 and a solar absorptivity of a = 0.60. The Inner surface of the wall is maintained at T₁ = 524 R at all times, while the outer surface is exposed to solar radiation that is incident at a rate of q solar = 300 Btu/h-ft2. The outer surface is also losing heat by radiation to deep space at O K. 0 Plate a solar o = 0.1714 x 10-8 Btu/h ft2 R4 Sun If the temperature of the outer surface of the wall is 556.39 R, determine the rate of heat transfer through the wall when steady operating conditions are reached. (Round your answer up to 2 decimal places.) 51 Btu/h-ft2 (per The rate of heat transfer through the wall when steady operating conditions are reached unit area)arrow_forward
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