The typical operation cycle of a common refrigerator is shownschematically in the figure . Both the condenser coils to the leftand the evaporator coils to the right contain a fluid (the workingsubstance) called refrigerant, which is typically in vapor-liquidphase equilibrium. The compressor takes in low-pressure,low-temperature vapor and compresses it adiabatically tohigh-pressure, high-temperature vapor, which then reaches thecondenser. Here the refrigerant is at a higher temperature thanthat of the air surrounding the condenser coils and it releasesheat by undergoing a phase change. The refrigerant leaves thecondenser coils as a high-pressure, high-temperature liquid andexpands adiabatically at a controlled rate in the expansion valve.As the fluid expands, it cools down. Thus, when it enters theevaporator coils, the refrigerant is at a lower temperature thanits surroundings and it absorbs heat. The air surrounding theevaporator cools down and most of the refrigerant in the evaporatorcoils vaporizes. It then reaches the compressor as a low-pressure,low-temperature vapor and a new cycle begins.
Part a)
Air conditioners operate on the same principle as refrigerators.Consider an air conditioner that has 7.00 kg of refrigerant flowingthrough its circuit each cycle. The refrigerant enters theevaporator coils in phase equilibrium, with 54.0 \% of its mass asliquid and the rest as vapor. It flows through the evaporator at aconstant pressure and when it reaches the compressor 95\% of itsmass is vapor. In each cycle, how much heat Q_c is absorbed by therefrigerant while it is in the evaporator? The heat of vaporizationof the refrigerant is 1.50Ã105 J/kg.
part B) In each cycle, the change in internal energy of therefrigerant when it leaves the compresser is 1.20Ã105 J. What isthe work W done by the motor of the compressor?
The typical operation cycle of a common refrigerator is shownschematically in the figure . Both the condenser coils to the leftand the evaporator coils to the right contain a fluid (the workingsubstance) called refrigerant, which is typically in vapor-liquidphase equilibrium. The compressor takes in low-pressure,low-temperature vapor and compresses it adiabatically tohigh-pressure, high-temperature vapor, which then reaches thecondenser. Here the refrigerant is at a higher temperature thanthat of the air surrounding the condenser coils and it releasesheat by undergoing a phase change. The refrigerant leaves thecondenser coils as a high-pressure, high-temperature liquid andexpands adiabatically at a controlled rate in the expansion valve.As the fluid expands, it cools down. Thus, when it enters theevaporator coils, the refrigerant is at a lower temperature thanits surroundings and it absorbs heat. The air surrounding theevaporator cools down and most of the refrigerant in the evaporatorcoils vaporizes. It then reaches the compressor as a low-pressure,low-temperature vapor and a new cycle begins.
Part a)
Air conditioners operate on the same principle as refrigerators.Consider an air conditioner that has 7.00 kg of refrigerant flowingthrough its circuit each cycle. The refrigerant enters theevaporator coils in phase equilibrium, with 54.0 \% of its mass asliquid and the rest as vapor. It flows through the evaporator at aconstant pressure and when it reaches the compressor 95\% of itsmass is vapor. In each cycle, how much heat Q_c is absorbed by therefrigerant while it is in the evaporator? The heat of vaporizationof the refrigerant is 1.50Ã105 J/kg.
part B) In each cycle, the change in internal energy of therefrigerant when it leaves the compresser is 1.20Ã105 J. What isthe work W done by the motor of the compressor?
