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Q1) A closed system contains 1.2 kg of air (assumed ideal gas) initially at 400 K and 300 kPa in a piston-cylinder arrangement. The air is compressed isentropically to a final pressure of 900 kPa. Assuming Cp = 1.005 kJ/kg·K and γ = 1.4, determine the final temperature and volume of the air. Then, calculate the work done on the gas and the change in internal energy during the process. Explain how the isentropic relation T₂/T₁ = (P₂/P₁)^((γ–1)/γ) is derived, and comment on the physical meaning of isentropic compression in practical devices like compressors. Q2) In a Carnot refrigeration cycle operating between 5°C (cold reservoir) and 45°C (hot reservoir), the refrigerator absorbs 150 kJ of heat from the cold body. Calculate the coefficient of performance (COP) of the system and the work input required. Then, determine how much heat is rejected to the high-temperature reservoir. Derive the COP expression for a Carnot refrigerator and explain why this theoretical limit cannot be achieved in real systems. Support your explanation with at least one practical reason related to irreversibilities or friction.

Name: q1 a closed system contains 12 kg of air assumed ideal gas initially at 400 k and 300 kpa in a piston cylinder arrangement the air is compressed isentropically to a final pressure of 900 kpa 64584
Uploaded: 2023-06-30T11:36:52-08:00
Duration: 1 min 41 s
Channel: Adi S
Description: q1 a closed system contains 12 kg of air assumed ideal gas initially at 400 k and 300 kpa in a piston cylinder arrangement the air is compressed isentropically to a final pressure of 900 kpa 64584

          Q1)
A closed system contains 1.2 kg of air (assumed ideal gas) initially at 400 K and 300 kPa in a piston-cylinder arrangement. The air is compressed isentropically to a final pressure of 900 kPa. Assuming Cp = 1.005 kJ/kg·K and γ = 1.4, determine the final temperature and volume of the air. Then, calculate the work done on the gas and the change in internal energy during the process. Explain how the isentropic relation T₂/T₁ = (P₂/P₁)^((γ–1)/γ) is derived, and comment on the physical meaning of isentropic compression in practical devices like compressors.
Q2)
In a Carnot refrigeration cycle operating between 5°C (cold reservoir) and 45°C (hot reservoir), the refrigerator absorbs 150 kJ of heat from the cold body. Calculate the coefficient of performance (COP) of the system and the work input required. Then, determine how much heat is rejected to the high-temperature reservoir. Derive the COP expression for a Carnot refrigerator and explain why this theoretical limit cannot be achieved in real systems. Support your explanation with at least one practical reason related to irreversibilities or friction.

Added by Juan Francisco M.

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