Reconsider Prob. 12-98. Using EES (or other) software, plot the net rate of solar energy t...

Reconsider Prob. 12-98. Using EES (or other) software, plot the net rate of solar energy transferred to water as a function of the absorptivity of the absorber plate. Let the absorptivity vary from 0.5 to 1.0, and discuss the results.

Prob. 12-98

The absorber surface of a solar collector is made of aluminum coated with black chrome (αs = 0.87 and ε = 0.09). Solar radiation is incident on the surface at a rate of 600 W/m2. The air and the effective sky temperatures are 25°C and 15°C, respectively, and the convection heat transfer coefficient is 10 W/m2·K. For an absorber surface temperature of 70°C, determine the net rate of solar energy delivered by the absorber plate to the water circulating behind it.

FIGURE P12-98