An Air Conditioner: Refrigerator or Heat Pump?
The typical operation cycle of a common refrigerator is shown schematically in the figure . Both the condenser coils to the left and the evaporator coils to the right contain a fluid (the working substance) called refrigerant, which is typically in vapor-liquid phase equilibrium. The compressor takes in low-pressure, low-temperature vapor and compresses it adiabatically to high-pressure, high-temperature vapor, which then reaches the condenser. Here the refrigerant is at a higher temperature than that of the air surrounding the condenser coils and it releases heat by undergoing a phase change. The refrigerant leaves the condenser coils as a high-pressure, high-temperature liquid and expands adiabatically at a controlled rate in the expansion valve. As the fluid expands, it cools down. Thus, when it enters the evaporator coils, the refrigerant is at a lower temperature than its surroundings and it absorbs heat. The air surrounding the evaporator cools down and most of the refrigerant in the evaporator coils vaporizes. It then reaches the compressor as a low-pressure, low-temperature vapor and a new cycle begins.
A. Air conditioners operate on the same principle as refrigerators. Consider an air conditioner that has 7.00 of refrigerant flowing through its circuit each cycle. The refrigerant enters the evaporator coils in phase equilibrium, with 54.0 of its mass as liquid and the rest as vapor. It flows through the evaporator at a constant pressure and when it reaches the compressor 95 of its mass is vapor. In each cycle, how much heat is absorbed by the refrigerant while it is in the evaporator? The heat of vaporization of the refrigerant is 1.5×105 .
Express your answer numerically in joules.
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B. In each cycle, the change in internal energy of the refrigerant when it leaves the compresser is 1.2×105 . What is the work done by the motor of the compressor?
Express your answer in joules.
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C. Not available