Question

The temperature in the freezer compartment of a household refrigerator is kept at 0 degrees F. On a summer day the ambient temperature is 92 degrees F. The effective COP of the refrigerator (Q2/W where Q2 is the heat removed from the frozen food compartment and W is the electrical work required) is only one-tenth of that achievable by an ideal Carnot refrigerator. If electric power costs 10 cents/kWh (1 watt is 1 joule for 1 second), what is the cost of making one hundred 50-g ice cubes? Assume that the heat of fusion for ice is 80 cal/g and that when the ice cube trays are put in the refrigerator, the water temperature is 77 degrees F. The specific heat capacity of ice is 0.5 cal/g K, half that of liquid water.