Calculate the overall heat loss coefficient for a solar collector with a single glass cover having the following specifications:

The solution to this problem requires trial and error. Start by assuming a glass temperature and then determine whether the heat gained by the glass equals the heat loss from the glass at that temperature. If the heat gain is larger than the heat loss, repeat the calculations with a slightly higher temperature. After you have calculated the heat loss coefficient, compare your answer with the one obtained from Equation 7.23.

Equation 7.23

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Spacing between plate and glass cover Plate emittance Plate absorptance at equilibrium temperature Ambient air temperature Wind speed Back insulation thickness Conductivity of back insulation material Mean plate temperature Collector tilt 5 cm 0.2 0.2 283 K 3 m/s 3 cm 0.04 W/m K 340 K 45