A 0.6m diameter sphere is suspended in an enclosure. The ball is kept at a constant 200oC, while the enclosure is kept at 25oC. a) If the enclosure is opaque, how much radiation is emitted by the ball into the enclosure? b) If the enclosure is not opaque, it does not form a black body. Let’s say the enclosure has a transmissivity of 0.6 and a reflectivity of 0.2. How much thermal radiation is absorbed by the enclosure?

A 0.6m diameter sphere is suspended in an enclosure. The ball is kept at a constant 200oC, while the enclosure is kept at 25oC. a) If the enclosure is opaque, how much radiation is emitted by the ball into the enclosure? b) If the enclosure is not opaque, it does not form a black body. Let’s say the enclosure has a transmissivity of 0.6 and a reflectivity of 0.2. How much thermal radiation is absorbed by the enclosure?

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter11: Heat Transfer By Radiation

Section: Chapter Questions

Problem 11.22P

See similar textbooks

Similar questions

A tungsten filament is heated to 2700 K. At what wavelength is the maximum amount of radiation emitted? What fraction of the total energy is in the visible range (0.4to0.75m)? Assume that the filament radiates as a graybody.
11.31 A large slab of steel 0.1 m thick contains a 0.1 -m-di- ameter circular hole whose axis is normal to the surface. Considering the sides of the hole to be black, specify the rate of radiative heat loss from the hole. The plate is at 811 K, and the surroundings are at 300 K.
1.28 The sun has a radius of and approximates a blackbody with a surface temperature of about 5800 K. Calculate the total rate of radiation from the sun and the emitted radiation flux per square meter of surface area.
1.26 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 .
Two large parallel plates with surface conditions approximating those of a blackbody are maintained at 816C and 260C, respectively. Determine the rate of heat transfer by radiation between the plates in W/m2 and the radiative heat transfer coefficient in W/m2K.
11.68 Two infinitely large, black, plane surfaces are 0.3 m apart, and the space between them is filled by an isothermal gas mixture at 811 K and atmospheric pressure. The gas mixture consists of by volume. If one of the surfaces is maintained at 278 K and the other at 1390 K, calculate (a) the effective emissivity of the gas at its temperature, (b) the effective absorptivity of the gas to radiation from the 1390 K surface, (c) the effective absorptivity of the gas to radiation from the 278 K surface, and (d) the net rate of heat transfer to the gas per square meter of surface area.
Two panels of different materials are spaced 6m apart and at a 30-degree angle. The top panel is 2m x 1m. The top panel has an emissivity of 0.6. The bottom panel is made of a translucent material and has an absorptivity of 0.2 and a reflectivity of 0.5. a) If the top panel is kept at 100oC and the bottom panel at −50oC, how much radiation is the top panel emitting to the bottom panel? b) How much of that radiation passes through the bottom panel? c) What is the irradiation power, G?
Find the emissive power of a black body with surface temperature of 1000 K and wavelengthof (1) μm. uses charts/table also if needed
3.5m 12.0m 6m -3.5m
A light of a given wavelength is shining through a double slit plate with slits of width a and slit separation d which produces a diffraction pattern on a screen some distance away. If the intensity pattern for the double slit diffraction aspect of this setup is: And the intensity pattern for the single slit diffraction aspect of this setup is: Which of the following intensity plots best represents what you would see on the screen:
A half cylindrical shell with a radius of 75 cm is held at 200°C and has an emissivity of 0.4. A long 200°C R= 75 cm cylinder has a diameter of 30 cm and is placed 20°C E= 0.4 D= 30 cm concentrically with the shell. The cylinder is radiatively black. At the instant the cylinder is 20°C, how much heat is exchanged from the shell to the cylinder, per meter length into the page, i.e., Qshell-eylinder/L.
An object has a surface area 3.5 m) with ( 8.2 um) peak wavelength of emission, treating it as a blackbody, find the net rate at which it will radiate energy to ( 20 C) room?