8-101 One method of passive solar heating is to stack gal- lons of liquid water inside the buildings and expose them to the sun. The solar energy stored in the water during the day is released at night to the room air, providing some heating. Con- sider a house that is maintained at 22C and whose heating is assisted by a 350-L water storage system. If the water is heated to 45C during the day, determine the amount of heating this water will provide to the house at night. Assuming an outside temperature of 5C, determine the exergy destruction associ- ated with this process. Answers: 33,548 kJ, 1172 kJ 8-102 The inner and outer surfaces of a 0.5-cm-thick, 2-m x 2-m window glass in winter are 10C and 3C, respec- tively. If the rate of heat loss through the window is 3.2 kJ/s, determine the amount of heat loss, in kJ, through the glass over a period of 5 h. Also, determine the exergy destruction associated with this process. Take To 5C. 8-103 An aluminum pan has a flat bottom whose diameter is 20 cm. Heat is transferred steadily to boiling water in the pan through its bottom at a rate of 800 W. If the temperatures of the inner and outer surfaces of the bottom of the pan are 104C and 105C, respectively, determine the rate of exergy destruction within the bottom of the pan during this process, in W. Take To = 25C. 8-104 A crater lake has a base area of 20,000 m, and the water it contains is 12 m deep. The ground surrounding the crater is nearly flat and is 140 m below the base of the lake. Determine the maximum amount of electrical work, in kWh, that can be generated by feeding this water to a hydroelectric power plant. Answer: 95,500 kWh 8-105E A refrigerator has a second-law efficiency of 45 percent, and heat is removed from the refrigerated space at a rate of 200 Btu/min. If the space is maintained at 35F while the surrounding air temperature is 75F, determine the power input to the refrigerator.