Review. (a) A homeowner has a solar water heater installed

Chapter 34, Problem 69

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Review. (a) A homeowner has a solar water heater installed on the roof of his house (Fig. P34.69). The heater is a flat, closed box with excellent thermal insulation. Its interior is painted black, and its front face is made of insulating glass. Its emissivity for visible light is 0.900, and its emissivity for infrared light is 0.700. Light from the noontime Sun is incident perpendicular to the glass with an intensity of 1 000 W/m2, and no water enters or leaves the box. Find the steadystate temperature of the boxs interior. (b) What If? The homeowner builds an identical box with no water tubes. It lies flat on the ground in front of the house. He uses it as a cold frame, where he plants seeds in early spring. Assuming the same noontime Sun is at an elevation angle of 50.0, find the steady-state temperature of the interior of the box when its ventilation slots are tightly closed.