Consider a refrigeration cycle which uses CO as a refrigerant in an ordinary vapor-compression cycle. The...

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Consider a refrigeration cycle which uses CO₂ as a refrigerant in an ordinary vapor-compression cycle. The cycle is to absorb heat at -20°C and reject heat at 20°C. Assume the compressor is reversible. Use the attached pressure-enthalpy diagram to answer the following questions. a. Sketch the cycle on the pressure-enthalpy diagram. Label the outlet of the condenser as Stream 1, the outlet of the expansion valve as Stream 2, the outlet of the evaporator as Stream 3, and the outlet of the compressor as Stream 4. What is the quality of the stream exiting the expansion valve? b. c. Determine the coefficient of performance for this cycle. d. Determine the flowrate of CO₂ needed if the system is to provide 1 kW of cooling. e. Your colleague suggests that a coefficient of performance cannot be greater than one as this would defy the first law of thermodynamics. Is this true? Justify your answer numerically. Your colleague also suggests that a coefficient of performance greater than one defies the second law of thermodynamics. Is this true? Explain, in words, how you would show if this is true or not. What further information would you need, if any? f. Consider a refrigeration cycle which uses CO₂ as a refrigerant in an ordinary vapor-compression cycle. The cycle is to absorb heat at -20°C and reject heat at 20°C. Assume the compressor is reversible. Use the attached pressure-enthalpy diagram to answer the following questions. a. Sketch the cycle on the pressure-enthalpy diagram. Label the outlet of the condenser as Stream 1, the outlet of the expansion valve as Stream 2, the outlet of the evaporator as Stream 3, and the outlet of the compressor as Stream 4. What is the quality of the stream exiting the expansion valve? b. c. Determine the coefficient of performance for this cycle. d. Determine the flowrate of CO₂ needed if the system is to provide 1 kW of cooling. e. Your colleague suggests that a coefficient of performance cannot be greater than one as this would defy the first law of thermodynamics. Is this true? Justify your answer numerically. Your colleague also suggests that a coefficient of performance greater than one defies the second law of thermodynamics. Is this true? Explain, in words, how you would show if this is true or not. What further information would you need, if any? f.

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a To sketch the cycle on a pressureenthalpy diagram you need to understand the basic vaporcompression refrigeration cycle On the diagram youll typical... View the full answer