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Question1 (15 marks) Solar radiation is incident on a solar absorber plate surface at a rate of 800 W/m². Ninety-three percent of the solar radiation is absorbed by the plate. The surface temperature of the plate is $T_s$ = 40°C with an emissivity, $\varepsilon$ = 0.9. It experiences radiation exchange with the surrounding temperature, $T_{surr}$ = -5°C. In addition, convective heat transfer occurs between the plate surface and the ambient air at $T_\infty$ = 20°C with a convection heat transfer coefficient of h = 7 W/m²K. If surface area of the plate, $A_s$ = 5 m², determine a) the total heat transfer rate from the plate surface, Watt, and b) the percentage ratio of usable heat* relative to solar radiation incident, %. Stefan-Boltzmann constant, $\sigma$ = 5.67 x 10$^{-8}$ W/m² K$^4$. * Usable heat = Heat absorbed by surface - total heat transfer rate from the surface.

          Question1 (15 marks)
Solar radiation is incident on a solar absorber plate surface at a rate of 800 W/m². Ninety-three
percent of the solar radiation is absorbed by the plate. The surface temperature of the plate is
$T_s$ = 40°C with an emissivity, $\varepsilon$ = 0.9. It experiences radiation exchange with the surrounding
temperature, $T_{surr}$ = -5°C. In addition, convective heat transfer occurs between the plate surface
and the ambient air at $T_\infty$ = 20°C with a convection heat transfer coefficient of h = 7 W/m²K. If
surface area of the plate, $A_s$ = 5 m², determine
a) the total heat transfer rate from the plate surface, Watt, and
b) the percentage ratio of usable heat* relative to solar radiation incident, %.
Stefan-Boltzmann constant, $\sigma$ = 5.67 x 10$^{-8}$ W/m² K$^4$.
* Usable heat = Heat absorbed by surface - total heat transfer rate from the surface.

Question1 (15 marks)
Solar radiation is incident on a solar absorber plate surface at a rate of 800 W/m². Ninety-three
percent of the solar radiation is absorbed by the plate. The surface temperature of the plate is
Ts = 40°C with an emissivity, ε = 0.9. It experiences radiation exchange with the surrounding
temperature, Tsurr = -5°C. In addition, convective heat transfer occurs between the plate surface
and the ambient air at T∞ = 20°C with a convection heat transfer coefficient of h = 7 W/m²K. If
surface area of the plate, As = 5 m², determine
a) the total heat transfer rate from the plate surface, Watt, and
b) the percentage ratio of usable heat* relative to solar radiation incident, %.
Stefan-Boltzmann constant, σ = 5.67 x 10^-8 W/m² K^4.
* Usable heat = Heat absorbed by surface - total heat transfer rate from the surface.

Added by Emily Y.

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