Two aligned parallel square plates 0.6 m by 0.6 m are separated by L=0.3 m as illustrated in accompanying figure. Plate 1 is maintained at T;= 1000 K and it is assumed to be a blackbody. Plate 2 is maintained at T2=500 K and has an emissivity ɛ2 = 0.5. The plates are exposed through the opening between them into an ambient which can be regarded as a blackbody medium at T=300 K. (a)- Using appropriate graphs, tables, and governing laws, determine view factors F12, F13 and F23. (b)- Sketch the radiation network for the two surfaces and ambient. (c)- Calculate the radiosity (J) for surface 2.

Two aligned parallel square plates 0.6 m by 0.6 m are separated by L=0.3 m as illustrated in accompanying figure. Plate 1 is maintained at T;= 1000 K and it is assumed to be a blackbody. Plate 2 is maintained at T2=500 K and has an emissivity ɛ2 = 0.5. The plates are exposed through the opening between them into an ambient which can be regarded as a blackbody medium at T=300 K. (a)- Using appropriate graphs, tables, and governing laws, determine view factors F12, F13 and F23. (b)- Sketch the radiation network for the two surfaces and ambient. (c)- Calculate the radiosity (J) for surface 2.

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 11.38P

See similar textbooks

Similar questions

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.
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.
Determine the total average hemispherical emissivity and the emissive power of a surface that has a spectral hemispherical emissivity of 0.8 at wavelengths less than 1.5m, 0.6 at wavelengths from 1.5to2.5m, and 0.4 at wavelengths longer than 2.5m. The surface temperature is 1111 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.
Determine the rate of radiant heat emission in watts per square meter from a blackbody at (a) 15C, (b) 600C, and (c) 5700C.
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.
A small circular surface of area A1=2 cm2located at the center of a 2-m-diameter sphere emits radiation as a blackbody at T1= 1000 K. Determine the rate at which radiation energy is streaming through a D2=1-cm-diameter hole located (a) on top of the sphere directly aboveA1and (b) on the side of the sphere such that the line that connects the centres of A1 and A2 makes 45° with surface A1. (c) Repeat it for a 4-m diameter sphere.
The human skin is “selective” when it comes to theabsorption of the solar radiation that strikes it perpendicularly.The skin absorbs only 50 percent of the incident radiationwith wavelengths between l1 = 0.517 mm and l2 =1.552 mm. The radiation with wavelengths shorter than l1and longer than l2 is fully absorbed. The solar surface maybe modeled as a blackbody with effective surface temperatureof 5800 K. Calculate the fraction of the incident solar radiationthat is absorbed by the human skin.
Two very large parallel plates are kept at uniform temperatures T1=800 K and T2=500 K, and have emissivities ε1=0.2 y ε2=0.7, respectively, as shown in the figure. Determine the net rate of radiation heat transfer between the two surfaces per unit surface area of the plates.