A 4-m² square flat-plate solar collector for domestic hot-water heating is shown schematically. Solar radiation at a rate of 750 W/m² is incident on the glass cover, which transmits 90% of the incident flux. Water flows through the tubes soldered to the backside of the absorber plate, entering with a temperature of 25°C. The glass cover has a temperature of 27°C in the steady state and radiates heat with an emissivity of 0.92 to the sky at – 50°C. In addition, the glass cover loses heat by convection to air at 20°C flowing over its surface at 20 mph.

Transcribed Image Text:

Air flow 9,/A Air space Glass cover Insulation Absorber plate Tubing for fluid