Copper tubing is joined to the absorber of a flat-plate solar collector as shown.

The aluminum alloy (2024- T6) absorber plate is 6 mm thick and well insulated on its bottom. The top surface of the plate is separated from a transparent cover plate by an evacuated space. The tubes are spaced a distance L of 0.20 m from each other, and water is circulated through the tubes to remove the collected energy. The water may be assumed to be at a uniform temperature of Tw = 60°C. Under steady-state operating conditions for which the net radiation heat flux to the surface is qrad = 800 W/m2, what is the maximum temperature on the plate and the heat transfer rate per unit length of tube? Note that q'rad represents the net effect of solar radiation absorption by the absorber plate and radiation exchange between the absorber and cover plates. You may assume the temperature of the absorber plate directly above a tube to be equal to that of the water.

Transcribed Image Text:

Cover plate Evacuated space -Absorber plate Water L- Insulation