A solar panel mounted on a spacecraft has an area of 1 m2 and a solar-to-electrical power conversion efficiency of 12%. The side of the panel with the photo- voltaic array has an emissivity of 0.8 and a solar absorptivity of 0.8. The back side of the panel has an emissivity of 0.7. The array is oriented normal to solar irradiation of 1500 W/m 2 . (a) Determine the steady-state temperature of the panel and the electrical power (W) produced for the prescribed conditions. (b) If the panel were a thin plate without the solar cells, but with the same radiative properties, determine the temperature of the plate for the prescribed conditions. Compare this result with that from part (a). Are they the same or different? Explain why. (c) Determine the temperature of the solar panel 1500 s after the spacecraft is eclipsed by a planet. The thermal capacity of the panel per unit area is 000 j/m 2 ⋅ K .
A solar panel mounted on a spacecraft has an area of 1 m2 and a solar-to-electrical power conversion efficiency of 12%. The side of the panel with the photo- voltaic array has an emissivity of 0.8 and a solar absorptivity of 0.8. The back side of the panel has an emissivity of 0.7. The array is oriented normal to solar irradiation of 1500 W/m 2 . (a) Determine the steady-state temperature of the panel and the electrical power (W) produced for the prescribed conditions. (b) If the panel were a thin plate without the solar cells, but with the same radiative properties, determine the temperature of the plate for the prescribed conditions. Compare this result with that from part (a). Are they the same or different? Explain why. (c) Determine the temperature of the solar panel 1500 s after the spacecraft is eclipsed by a planet. The thermal capacity of the panel per unit area is 000 j/m 2 ⋅ K .
Solution Summary: The author analyzes the energy balance on the solar panel as shown above.
A solar panel mounted on a spacecraft has an area of 1 m2 and a solar-to-electrical power conversion efficiency of 12%. The side of the panel with the photo- voltaic array has an emissivity of 0.8 and a solar absorptivity of 0.8. The back side of the panel has an emissivity of 0.7. The array is oriented normal to solar irradiation of
1500 W/m
2
.
(a) Determine the steady-state temperature of the panel and the electrical power (W) produced for the prescribed conditions.
(b) If the panel were a thin plate without the solar cells, but with the same radiative properties, determine the temperature of the plate for the prescribed conditions. Compare this result with that from part (a). Are they the same or different? Explain why.
(c) Determine the temperature of the solar panel 1500 s after the spacecraft is eclipsed by a planet. The thermal capacity of the panel per unit area is
000 j/m
2
⋅
K
.
Two circular plates of radii r1= 4 cm and r2 = 2 cm are (9) cm apart. Find view factorF21.
6. An electric hot plate is placed in a room which is maintained at a temperature of 297 K.
The plate is maintained at a temperature of 403 K and has an emissivity of 0.8. If the plate
surface resembles a circular disc of diameter 250 mm, electrical power consumed by the hot
plate will be;
a. 22 W
b. 65 W
c. 75 W
d. 86 W
Irradiation on a semi-transparent medium is at a rate of 640 W/m². If 160
W/m² of the irradiation is reflected from the medium and 130 W/m² is
transmitted through the medium,
1) Determine the absorptivity of the medium.
2) Determine the reflectivity of the medium.
3) Determine the transmissivity of the medium.
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