Consider coaxial, parallel, black disks separated a distance of 0.20 m. The lower disk of diameter 0.40 m is maintained at 400 K and the surroundings are at 300 K. If the heater of diameter 0.2 m is at 500 K what is the electric power supplied to it? Consider heater as surface 1, lower disk as surface 2 and surrounding as surface 3.

Consider coaxial, parallel, black disks separated a distance of 0.20 m. The lower disk of diameter 0.40 m is maintained at 400 K and the surroundings are at 300 K. If the heater of diameter 0.2 m is at 500 K what is the electric power supplied to it? Consider heater as surface 1, lower disk as surface 2 and surrounding as surface 3.

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 11.29P

See similar textbooks

Similar questions

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.
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.
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.
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 .
Determine the view factor between two gray surfaces A and B. Their emissivities are εA = 0.90 and εB = 0.25 at temperatures 450°C and 50°C, respectively, if (1) surfaces are infinite black parallel planes, (2) surfaces are infinite gray parallel planes, (3) surface A is a spherical shell 3 m in diameter and surface B is a similar shell concentric with A and 0.3 m in diameter, (4) surfaces A and B concentric cylindrical tubes with diameters of 300 mm and 275 mm, respectively, (5) both surfaces are discs with diameter 2 m one exactly above the other, 1 m apart.