Heat engine and refrigerator. Consider a heat engine operating between temperatures Th and Tj. During each cycle with time At, work W is extracted, so Pout = W/At. (a) Assuming the processes are all reversible, what is the efficiency of this heat engine, n = Wout/Qn? (b) Now assume that the low temperature of the heat engine is lowered by a reversible refrigerator, such that the heat engine operates between Th and T. The refrigerator takes input power Pin = Win/At and operates between T and Ti, where T < TỊ. Draw an energy- entropy flow diagram. (c) Calculate the net efficiency (Wout - Win)/Qh. Is the efficiency of this system higher, lower, or the same as your answer for (a)?

Heat engine and refrigerator. Consider a heat engine operating between temperatures Th and Tj. During each cycle with time At, work W is extracted, so Pout = W/At. (a) Assuming the processes are all reversible, what is the efficiency of this heat engine, n = Wout/Qn? (b) Now assume that the low temperature of the heat engine is lowered by a reversible refrigerator, such that the heat engine operates between Th and T. The refrigerator takes input power Pin = Win/At and operates between T and Ti, where T < TỊ. Draw an energy- entropy flow diagram. (c) Calculate the net efficiency (Wout - Win)/Qh. Is the efficiency of this system higher, lower, or the same as your answer for (a)?

Refrigeration and Air Conditioning Technology (MindTap Course List)

8th Edition

ISBN:9781305578296

Author:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Publisher:John Tomczyk, Eugene Silberstein, Bill Whitman, Bill Johnson

Chapter45: Domestic Refrigerators And Freezers

Section: Chapter Questions

Problem 12RQ: Refrigerators currently being manufactured in the United States are using______as their refrigerant.

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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. Efficiency of the Carnot engine is 38%. For this information answer the following questions: A room is maintained at a constant temperature of 20 C and has a heat loss of 20,000 W. Consider this room for a period of 3 hours. The surroundings are at a temperature of TI. In one option the room is heated using resistive heaters that are operated with electricity. a)Determine the electrical energy input to these heaters. b)Determine the efficiency of this heating system. c)Determine the entropy production…
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. Efficiency of the Carnot engine is 38%. For this information answer the following questions: 1) A room is maintained at a constant temperature of 20 C and has a heat loss of 20,000 W. Consider this room for a period of 3 hours. The surroundings are at a temperature of TI. In one option the room is heated using resistive heaters that are operated with electricity. For the same conditions described in part 1 above, consider using a Carnot heat pump to supply the heat to the room. The low temperature…
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