Q/ Two Carnot refrigerators operate in series between two reservoirs maintained at 20°C and 200°C, respectively. The energy output by the first refrigerator is used as the heat energy input to the second refrigerator. If the COPS of the two refrigerators are the same, what should the intermediate temperature be?

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5) If water with a mass of 348 g with an initial temperature of 42° will be frozen in the refrigerator for 30 seconds to a temperature of -80° with a refrigerator performance coefficient of 5.00. Determine the refrigerator power input required when operating?

B) A reversible heat engine operates between two reservoirs at temperatures of 600°C and 40°C. The engine drives a reversible refrigerator which operates between reservoirs at temperatures of 40°C and -20°C. The heat transfer to the heat engine is 2000 kJ and the net work output for the combined engine refrigerator is 360 kJ. (i) Calculate the heat transfer to the refrigerant and the net heat transfer to the reservoir at 40°C. (ii) Reconsider (i) given that the efficiency of the heat engine and the C.O.P. of the refrigerator are each 40 per cent of their maximum possible values.

A "cold room" used for low-temperature research is maintained at a constant temperature of 7.00°C. The refrigeration unit vents to outdoor air which is at 27.0°C. The rate at which energy is exhausted to the outdoors is 18.0 kW. The coefficient of performance (COP) of the refrigeration unit is equal to 40.0% of the COP of an ideal Carnot refrigerator. (a) At what rate (in kW) does the refrigeration unit remove energy from the room? (Round your answer to at least two decimal places.) kW (b) What is the power input (in kW) required by the refrigeration unit? kW (c) What is the entropy change of the Universe (in J/K) produced by the refrigeration unit after it operates for 3.00 h? J/K (d) If the outside temperature increases to 33.0°C, what is the percent change in the COP of the refrigeration unit? (Include the sign of the value in your answer.) % Need Help? Read It