A laboratory requires 50kJ of heat to be supplied to a calorimeter each cycle. Two alternative devices are available:
Device M : A heat pump that absorbs heat from a sink at TC=280K and rejects heat to the calorimeter at TH=320K. The measured work input per cycle is 8kJ.
Device N : An electric resistance heater that converts the entire electrical work supplied into heat delivered to the calorimeter.
a) For Device M determine the amount of heat extracted from the cold sink and the heat rejected to the calorimeter per cycle.
b) Calculate the coefficient of performance of Device M and compare it with the theoretical maximum value possible between the stated temperatures.
c) Using the First Law of Thermodynamics, compute the electrical energy that Device N must consume per cycle to supply the required 50kJ of heat.
d) With reference to both the First and the Second Law, decide which device should be selected for the laboratory and justify your answer thoroughly.