1. A Carnot heat engine absorbs heat at a rate of 10 kJ/s from a source at 500°C and rejects the waste heat to the environment at 25°C. It is proposed that the heat engine will be used to drive a Carnot refrigerator that removes heat from the cooled space at -10°C and rejects it to the same environment at 25°C. i. Determine the minimum rate of heat removal from the cooled space.

1. A Carnot heat engine absorbs heat at a rate of 10 kJ/s from a source at 500°C and rejects the waste heat to the environment at 25°C. It is proposed that the heat engine will be used to drive a Carnot refrigerator that removes heat from the cooled space at -10°C and rejects it to the same environment at 25°C. i. Determine the minimum rate of heat removal from the cooled space.

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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b) Refrigerators are systems that are used to remove heat from a cooled space then reject heat to a space of higher temperature. Consider a refrigerator operating at normal conditions, removing heat from a cool space at a rate of 150 kJ/min to ensure the refrigerated space is kept at -5 °C. If the surrounding air is at 27 °C and assuming that the refrigerator is operating as a Carnot cycle, determine: 1) The rate of heat being rejected to the surrounding in kJ/min The coefficient of performance of this refrigeration process 11) 111) The minimum required power on this process (give your answer in kW)
A CARNOT heat engine receives heat from a reservoir at 900°C at a rate of 800kJ/min and rejects the waste heat to the ambient air at 27°C. All the power produced by the thermal engine is used to act as a refrigerator that removes heat from the refrigerated space at -5°C and transfers it to the same ambient air at 27°C. Determine a) the maximum rate of heat removal from the refrigerated space and b) the total rate of heat rejection to the ambient air.
Since Lucas is an engineer familiar with thermodynamics. He decided to create his own heat engine at home to avoid paying for electricity. He created a small, makeshift heat engine for trial. The combustion of his fuel, diesel, reaches a temperature of 750°C, while waste heat is disposed to the atmosphere at 50°C.He, then connected a generator and a heat pump to the heat engine to check the amount of power being produced. Assume that the heat pump will be used to warm his room to 25°C, while the outside temperature is at 5°C. Lucas’ rooms loses 85,000 kJ/hr of heat. And, 25% of the heat engine’s power output goes to the heat pump. How much diesel (in kg) needs to be burned by the heat engine to maintain the temperature in Lucas’ room? Assume carnot heat engine and heat pump. If the natural gas has a heating value of 22,000 BTU/lb. *Round off all answers to four decimal places*
b) A Carnot heat engine receives heat at 890 K and rejects the waste heat to the environment at 30°C. The entire work output of the heat engine is used to drive a Carnot refrigerator that removes heat from the cooled space at -10°C at a rate of 280 kJ/min and rejects it to the same environment at 30°C. Determine (a) the rate of heat supplied to the heat engine and (b) the total rate of heat rejection to the environment
A heat pump operates with Refrigerant 134a as the working fluid. You are required to analyze its performance, and compare it with Camot heat pump. The data of the heat pump is as under: 23 - Thermodynamies-II Page 1 of 3 The heat pump is presently providing heating at a rate of 12 kW to maintain the interior of a building at 20°C. Outside temperature is 5°C. The refrigerant enters the compressor at 2.4 bar and increases the pressure to 8.0 bar. Efficiency of the compressor is 80%. a Temperatures at the principal states of the cycle, each °C b. Power input to the compressor, in kW c. Coefficient of performance Relate its performance with the specifications provided by the vendor i.e. COP = 8.5 and identify the possible reasons of differences. Draw Ts diagram
1. An inventor claims to have invented a heat engine that receives 750kJ of heat from a source at 400K and produces 250kJ of net work while rejecting the waste heat to a sink at 300K. Is this a reasonable claim? Why?
Since Lucas is an engineer familiar with thermodynamics. He decided to create his own heat engine at home to avoid paying for electricity. He created a small, makeshift heat engine for trial. The combustion of his fuel. diesel, reaches a temperature of 750°C, while waste heat is disposed to the atmosphere at 50°C. He, then connected a generator and a heat pump to the heat engine to check the amount of power being produced. Assume that the heat pump will be used to warm his room to 25°C, while the outside temperature is at 5°C. Lucas' rooms loses 85,000 kJ/hr of heat. And, 25% of the heat engine's power output goes to the heat pump. How much diesel (in kg) needs to be burned by the heat engine to maintain the temperature in Lucas' room? Assume carnot heat engine and heat pump. If the natural gas has a heating value of 22,000 BTU/lb.
(iii) What is the difference between a refrigerator and a heat pump?
Q) A Carnot heat engine receives heat from a reservoir at 800 °C at a rate of 12 kJ/s and rejects the waste heat to the ambient air at 27 °C. The half entire work output of the heat engine is used to drive a refrigerator that removes heat from the refrigerated space at -4°C and transfers it to the same ambient air at 27°C. Determine: (a) The maximum rate of heat removal from the refrigerated space. (b) The total rate of heat rejection to the ambient air.
3. A Carnot engine is coupled to a Carnot refrigerator so that all the work produced by the engine is used by the refrigerator in extraction of heat from a heat reservoir at 0 °C at the rate of 35 kJ/s. The source of energy of the Carnot engine is a heat reservoir at 250 °C. If both devices discard heat to the surroundings at 25 °C, how much heat does the engine absorb from its heat-source reservoir ? Draw a schematic diagram of the coupling of the heat engine and the refrigerator showing the direction of heat absorbed and discarded and the work involved.
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
A refrigerator has a coefficient of performance of 1.6. How much work in KJ must be supplied to this refrigerator for it to reject 1000 KJ of heat?