Air-Standard Cycle

Working fluid:

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Reversed Brayton Cycle:

Assumptions:

P-v and T-s Diagram:

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Control Volume:

First Law of Thermodynamics:

Second Law of Thermodynamics:

Pressure ratio: r=P2P1

Temperature Specific Volume
1→2 T2=T1rγ−1γ v2=v1r−1γ
3→4 T4=T3rγ−1γ v4=v3r−1γ

Work:

Specific Work
Compressor wcomp=CpT1[1−rγ−1γ]
Expander wexp=CpT3[1−rγ−1γ]
Net wnet=CPT1[(1−rγ−1γ)+T3T1(1−rγ−1γ)]

Heat:

Specific Heat
Intake qin=CPT1[1−T3T1rγ−1γ]
Exhaust qout=CPT1[T3T1−rγ−1γ]

Coefficient of Performance:

In laymans terms, β=what we wantwhat we give. This is not an Efficiency!

β=qin|wnet|=1rγ−1γ−1

Results:

Example: