13.44 The end of a cylindrical liquid cryogenic propellanttank in free space is to be protected from external(solar) radiation by placing a thin metallic shield infront of the tank. Assume the view factor Fts betweenthe tank and the shield is unity; all surfaces are diffuseand gray, and the surroundings are at 0 K.TankT₁Shield, TT₁ = 100 KE1SolarirradiationGsε₁ = ε₂ = 0.05ε₁ = 0.10Gs = 1250 W/m²E2Find the temperature of the shield T, and the heat flux(W/m²) to the end of the tank.

Step 1: Explanation:1.) The sun heats the shield by sending energy at 1250 W/m².2.) The shield gets…

Answered: 13.44 The end of a cylindrical liquid…

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 11.49P

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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.
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.
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.
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.
A typical car's exterior consists of a thin layer of silica (SiO2) over an opaque painted metal panel. Silica is transparent in the visible wavelengths but offers high reflectance in the near- to mid- infrared wavelengths. The plot on the next page depicts the diffuse spectral reflectivity (pa) of the car's surface: Spectral reflectivity, P₂ 0.8 0.6 0.4 ལ 0.2 0 0.1 1 1 10 Wavelength, λ(μm) 100 If the car's exterior temperature is T₁ = 77°C, determine both the total absorptivity (a) and the total emissivity (a) of the silica-covered panel. Assume that the Sun's temperature is Tsun = 5800 K.
as fast as.
The last portion asks you for "net radiant heat flux to the surface", meaning that positive net radiative heat flux means in and negative net radiative heat flux means out. This is opposite the typical sign convention - be aware of this
A horizontal opaque flat plate is well insulated on the edges and the lower surface. The top surface has an area of 5 m2, and it experiences uniform irradiation at a rate of 5000 W. The plate absorbs 4000 W of the irradiation, and the surface is losing heat at a rate of 500 W by convection. If the plate maintains a uniform temperature of 350 K, determine the absorptivity, reflectivity, and emissivity of the plate.
An opaque surface with the prescribed spectral, hemispherical reflectivity distribution is subject to the spectral irradiation shown. Find: 1.0 600 0.5 0 05 10 15 λ (μm) G₂(W/m²•μm) 300 0 0 5 10 15 20 20 λ (μm) (1) Find the spectral absorptivity distribution (αλ). (2) Determine the total irradiation G on the surface (3) Determine the radiant flux that is absorbed by the surface. (4) The total absorptivity a.
An engineered passive radiative cooler coating is placed under the Sun. Provided the following simplified spectral emissivity/absorptivity plot below, calculate the total diffuse emissivity and absorptivity if its uniform surface temperature is a Ts=20°C. Assume the Sun's irradiation onk Earth is Gsun=1380 W/m2 and its blackbody temperature is Tsun= 5800K. Ignore the radiation from the atmosphere (surroundings).

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