ME 222 Assignment 1. A heat pump which is a reversed heat engine takes in heat from a reservoir at 40C and delivers it to a reservoir at 77oC. The work input to the heat pump is from a reversible heat engine which receives heat from a reservoir at 10950C and rejects heat to the reservoir at 770C. If the amount of heat supplied to the reservoir at 770C is to be 105.5KW, find the heat to be supplied from the reservoir at 10950C 15 2. Develop the expression for the thermal efficiency of an engine working on the Carnot Cycle in terms of temperature limits. An Engine using air (y-1.4 as the working medium is assumed to work on Carnot Cycle between the temperature limits 3650C and 260C and between pressure limits of 100bar and 1.0 bar. Determine i. The pressure at the end of Isothermal expansion ii. The work done during the cycle iii. The thermal efficiency 3. A heat pump is to be used to heat a building during the cold season. The building is to be maintained at 21°C at all times. The building is estimated to be losing heat at a rate of 135,000 kJ/h when the outside temperature drops to -5°C. Determine the minimum power required to drive the hear pump unit for this outside temperature (the heat lost by the building has to be supplied by the heat pump) 34 km ( 4. Consider a Carnot refrigeration cycle executed in a closed system in the saturated liquid-vapor mixture region using 0.8 kg of refrigerant-134a as the working fluid. The maximum and the minimum temperatures in the cycle are 20°C and 8°C, respectively. It is known that the refrigerant is saturated liquid at the end of the heat rejection process, and the network input to the cycle is 15 kJ. Determine the fraction of the mass of the refrigerant that vaporizes during the heat addition process and the pressure at the end of the heat rejection process 5. A heat engine operates between two reservoirs at 800 and 20°C. One-half of the work output of the heat engine is used to drive a Carnot heat pump that removes heat from the cold surroundings at 2°C and transfers it to a house maintained at 22°C. If the house is losing heat at a rate of 62,000 kJ/h, determine the minimum rate of heat supply to the heat engine required to keep the house at 22°C. ۲۴

ME 222 Assignment 1. A heat pump which is a reversed heat engine takes in heat from a reservoir at 40C and delivers it to a reservoir at 77oC. The work input to the heat pump is from a reversible heat engine which receives heat from a reservoir at 10950C and rejects heat to the reservoir at 770C. If the amount of heat supplied to the reservoir at 770C is to be 105.5KW, find the heat to be supplied from the reservoir at 10950C 15 2. Develop the expression for the thermal efficiency of an engine working on the Carnot Cycle in terms of temperature limits. An Engine using air (y-1.4 as the working medium is assumed to work on Carnot Cycle between the temperature limits 3650C and 260C and between pressure limits of 100bar and 1.0 bar. Determine i. The pressure at the end of Isothermal expansion ii. The work done during the cycle iii. The thermal efficiency 3. A heat pump is to be used to heat a building during the cold season. The building is to be maintained at 21°C at all times. The building is estimated to be losing heat at a rate of 135,000 kJ/h when the outside temperature drops to -5°C. Determine the minimum power required to drive the hear pump unit for this outside temperature (the heat lost by the building has to be supplied by the heat pump) 34 km ( 4. Consider a Carnot refrigeration cycle executed in a closed system in the saturated liquid-vapor mixture region using 0.8 kg of refrigerant-134a as the working fluid. The maximum and the minimum temperatures in the cycle are 20°C and 8°C, respectively. It is known that the refrigerant is saturated liquid at the end of the heat rejection process, and the network input to the cycle is 15 kJ. Determine the fraction of the mass of the refrigerant that vaporizes during the heat addition process and the pressure at the end of the heat rejection process 5. A heat engine operates between two reservoirs at 800 and 20°C. One-half of the work output of the heat engine is used to drive a Carnot heat pump that removes heat from the cold surroundings at 2°C and transfers it to a house maintained at 22°C. If the house is losing heat at a rate of 62,000 kJ/h, determine the minimum rate of heat supply to the heat engine required to keep the house at 22°C. ۲۴

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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