A Carnot refrigerator operates between a cold space at –5 °C and the surroundings at 35 °C.
(i) Calculate the maximum possible COP of the refrigerator.
(ii) An actual refrigerator working between the same temperatures has an efficiency that is only 40 % of the Carnot value. Find its COP.
(iii) Three kilograms of water at 0 °C are to be converted into ice at 0 °C. (Latent heat of fusion of ice = 3.36×105Jkg−1.) Determine the minimum mechanical work required if the refrigerator were ideal (Carnot).
(iv) Calculate the mechanical work required for the actual refrigerator described in part (ii).