(a) An inventor claims to have developed a refrigeration unit with a COP of 8.5 which maintains the refrigerated space at -10oC while operating in a room where the temperature is 25oC. Can this claim be correct?
(b) Consider an engine in outer space which operates on the Carnot cycle. The only way in which heat can be transferred from the engine is by radiation. The rate at which the heat is radiated is proportional to the fourth power of the absolute temperature and to the area of the radiating surface. Show that for a given power output and a given TH, the area of the radiator will be a minimum when TL/TH = ¾.