Neglecting the effects of radiation absorption, emission, and scattering within their atmospheres, calculate the average temperature of Earth, Venus, and Mars assuming diffuse, gray behavior. The average distance from the sun of each of the three planets, L s − p , along with their measured average temperatures, T p ' ¯ , are shown in the table below. Based upon a comparison of the calculated and measured average temperatures, which planet is most affected by radiation transfer in its atmosphere?
Neglecting the effects of radiation absorption, emission, and scattering within their atmospheres, calculate the average temperature of Earth, Venus, and Mars assuming diffuse, gray behavior. The average distance from the sun of each of the three planets, L s − p , along with their measured average temperatures, T p ' ¯ , are shown in the table below. Based upon a comparison of the calculated and measured average temperatures, which planet is most affected by radiation transfer in its atmosphere?
Solution Summary: The author explains the energy balance for each planet is between absorbed solar radiation and emitted radiation. At a distance Rs from the sun, the radiation passes through the spherical area 4Rs2 resulting
Neglecting the effects of radiation absorption, emission, and scattering within their atmospheres, calculate the average temperature of Earth, Venus, and Mars assuming diffuse, gray behavior. The average distance from the sun of each of the three planets,
L
s
−
p
, along with their measured average temperatures,
T
p
'
¯
, are shown in the table below. Based upon a comparison of the calculated and measured average temperatures, which planet is most affected by radiation transfer in its atmosphere?
A thin, disk-shaped silicon wafer of diameter D=20 cm on a production line must be maintained at a temperature of 100 deg C. The wafer loses heat to the room by convection and radiation from its upper surface, while heat is supplied at a constant flux from below. The surrounding air is at 20 deg C, while all surrounding surfaces (which can be treated as blackbodies) can be approximated to be isothermal at a temperature of 15 deg C. The wafer-to-air heat transfer coefficient is 30 W/m2-K and the emissivity of the wafer’s surface (which can be approximated to be gray) is 0.85. How much heat (in W) must be supplied to the wafer?
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.
Two parallel gray planes that are very large have emissivities of ε1 = 0.8 and ε2 = 0.7; surface 1 is at 1100°F (866.5 K) and surface 2 is at 600°F (588.8 K). Use SI units for the following:
(a) What is the net radiation from 1 to 2?
(b) If the surfaces are both black, what is the net radiation?
Applied Statics and Strength of Materials (6th Edition)
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