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Second law of thermodynamics, entropy

Problem 2.114

Hydrogen is used in a Carnot cycle as a working substance. Find the efficiency of the cycle, if as a result of an adiabatic expansion (a) the gas volume increases \(n=2.0\) times; (b) the pressure decreases \(n=2.0\) times.

Reveal Answer
 (a) η=1−n1−γ=0.25 (b) η=1−n1/γ−1=0.18\text { (a) } \eta=1-n^{1-\gamma}=0.25 \text { (b) } \eta=1-n^{1 / \gamma-1}=0.18
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