Consider three reservoirs that are TH = 473.2 K, TL = 293.2 K and TI = 277.2 K. A Carnot heat engine can be reversed and used as either a heat pump or a refrigerator. In the case of a heat pump the heat flow to the higher temperature reservoir is the desired output and it is used to heat a room or building. In the case of the refrigerator the desired energy flow is the heat in from a region to be cooled. For the heat pump or refrigerator, the work input is provided by electricity. A region is to be cooled to a temperature of 277 K using a heat powered Carnot refrigerator. The heat that must be removed is 15,000 W. The heat rejected from the refrigerator is to a heat reservoir at TL. The heat input to this device is from a reservoir at TH. This is a Carnot model of an absorber refrigeration system. In it a Carnot heat engine operates between reservoirs at TH and TL. The work output from this Carnot heat engine is the input to a Carnot refrigerator that operates between TI and TL. Consider the cooling for a period of 3 hours. Answer the following: a)Determine the heat energy input to this Carnot refrigerator. b)Determine the Coefficient of Performance (COP, the efficiency) of this cooling system. c)Determine the entropy production for this this cooling system. In this case you should include the entropy production of the heat loss process from TI , TL and TH. d) The cost of the fuel to operate this system is $0.075/kWh. What is the cost to cool the room for 3 hours?
Consider three reservoirs that are TH = 473.2 K, TL = 293.2 K and TI = 277.2 K. A Carnot heat engine can be reversed and used as either a heat pump or a refrigerator. In the case of a heat pump the heat flow to the higher temperature reservoir is the desired output and it is used to heat a room or building. In the case of the refrigerator the desired energy flow is the heat in from a region to be cooled. For the heat pump or refrigerator, the work input is provided by electricity.
A region is to be cooled to a temperature of 277 K using a heat powered Carnot refrigerator. The heat that must be removed is 15,000 W. The heat rejected from the refrigerator is to a heat reservoir at TL. The heat input to this device is from a reservoir at TH. This is a Carnot model of an absorber refrigeration system. In it a Carnot heat engine operates between reservoirs at TH and TL. The work output from this Carnot heat engine is the input to a Carnot refrigerator that operates between TI and TL. Consider the cooling for a period of 3 hours.
Answer the following:
a)Determine the heat energy input to this Carnot refrigerator.
b)Determine the Coefficient of Performance (COP, the efficiency) of this cooling system.
c)Determine the entropy production for this this cooling system. In this case you should include the entropy production of the heat loss process from TI , TL and TH.
d) The cost of the fuel to operate this system is $0.075/kWh. What is the cost to cool the room for 3 hours?
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