A solar heater consists of a curved reflecting mirror that focusessunlight on an

Question

A solar heater consists of a curved reflecting mirror that focusessunlight on an object. The solar power per unit area reaching theEarth at the location of 0 .5 m-diameter solar heater is 600W/m2. Assuming that only 50% of the incident energy isconverted to heat energy, how long will it take this heater toevaporate 1.0 L of Water, initially at 20o C? (Neglectthe specific heat of the container holding the Water.) (1 L =1000g, c = 1 cal/goC, Latent Heat of Vaporization forwater L=540 cal / g, 1 cal = 4.186 J )

Explanation / Answer

diameter d = 0.5 m Area   A= d ^ 2 / 4 = 0.1963 m ^ 2 Intensity I = 600 W / m ^ 2 Power P = IA              = 117.8 W energy per second E = 117.8 J Thermal energy per second E ' = 50 % of E = 0.5 E =58.904 J volume of water V = 1 L = 10 ^ -3 m ^ 3 mass m = V D = 10 ^ -3 m ^ 3 * 10 ^ 3 kg / m ^ 3                       = 1 kg Specific heat C = 4186 J / kg oC Latent heat of vaporisation L = 540 cal / g = 2260.44 * 10 ^ 3J / kg heat required to evaporate the water Q = mC dt +mL                                                             = 1 * 4186 * 80 + ( 1 * 2260.44* 10 ^ 3 )                                                             = 2595320 J time t = Q / E '           =44060.16 s           = 12.23h           = 12.23h

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.