Solar Water Heater?
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Question by hhhwwf13: Solar Water Heater?
In a solar water heater, radiant energy from the Sun is transferred to water that circulates through tubes in a rooftop collector. The solar radiation enters the collector through a transparent cover and warms the water in the tubes; this water is pumped into a holding tank. Assume that the efficiency of the overall system is 20% (that is, 80% of the incident solar energy is lost from the system). What collector area is necessary to raise the temperature of 200 L of water in the tank from 20°C to 40°C in 1.0 h when the intensity of incident sunlight is 700 W/m2?
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One Response to Solar Water Heater?
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20% of 700W/m^2 = 140W/m^2
You need:
Q = 200,000grams (4.184J/g.C)(20C) =16,736,000 Joules
So:
(16,736,000Joules)(1W-sec/1J) / (140W/m^2)(3600seconds)
= 33.2 m^2
(Ω)Jack
February 16, 2014 at 12:21 pm