Refrigerators are responsible for about 16th of the energy u

Refrigerators are responsible for about 1/6th of the energy use in an average home. For a typical kitchen refrigerator (with freezer), T_H might be 298 K while T_c might be 255 K. Assume that the refrigerator operates at the maximum theoretical COP. If the cost of electricity is 12 cents per kilowatt-hour, how much would it cost to make ice cubes from 1 Liter of water that is at room temperature? (1 L = 1000 cm^3 and the density of water is 1 g/cm^3)

Solution

COP = Tc / (Th - Tc)

= 255 / (298 - 255)

= 5.93

Q = QC = (1 x 4.186 x 20) + (1 x 333.55) = 417.27 kJ

W = Q / COP

W = 70.37 kJ

energy used ,W (in kWh) = 0.0195 kWh { 1 kWh = 1 KW x 3600 sec = 3600 kJ }

cost = 0.23 cents