A 2 x 2 m flat plate solar collector for domestic hot water heating is shown in the figure. The incident solar radiation on the glass cover, which transmits 90% of the incident flux, is 750 W/m2. Water flows through the tubes soldered to the backside of the absorber plate, entering at a temperature of 25°C. The temperature of the glass cover is 27°C, and it radiates heat with an emissivity of 0.92 to the sky at –50°C. Additionally, the glass cover losses heat by convection to air at 20°C flowing over its surface at 30 km/h. Assume that the radiation heat transfer between the absorber plate and glass cover and the heat transfer through the back and sides of the collector is negligible.

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A point source emits 200 radiant watts and has a luminous efficacy of 120 lumens/watt. Itsspatial distribution is spherically uniform. state any assumptions, check answer w bold text.  a) What is the luminous intensity of this source? 1910 cdb) What is the average illuminance on a unit sphere centered around the point source? 6000/pii lx or fcc) What is the illuminance at point p at the center of circular surface A? 212 Ixd) If surface A has a radius of 2 m, what is the illuminance at point q? 122 lxf) what is the total number of lumens incident onto surface a? ~2015lmg) The total reflectance of surface A is 0.50. What is the average exitance of surface A? 80 Im/m2