In a solar water heater, energy from the Sun is gathered by water that circulate
ID: 2048572 • Letter: I
Question
In a solar water heater, energy from the Sun is gathered by 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 13.0% (that is, 87% of the incident solar energy is lost from the system). What collector area (in square meters) is necessary to raise the temperature of 380 L of water in the tank from 20°C to 48°C in 2.5 h when the intensity of incident sunlight is 800 W/m2? The specific heat of water is 4186 J/kg·K. The density of water is 1.00 g/cm3.Explanation / Answer
Heat requirement = (120/1000)*1000*4186*(48-15) = 1.6576560*10^7 J Let the required collector area be S. We have 0.12*S*430 *3600*1.6 = 1.658*10^7 or S = 55.77 m^2