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Engineering Thermodynamics · Problem type
Possible or impossible?
Use this for “An inventor claims an engine with 55 % efficiency between 700 K and 350 K. Is it possible?”
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Could each device work, or does it break the second law?
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No engine beats the Carnot efficiency of its two reservoirs.
Assumptions
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Kelvin–Planck: no cycle turns all the heat from one reservoir into work.
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Clausius: heat never flows from cold to hot by itself; that takes work.
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Between two reservoirs no engine beats 1 − TL ÷ TH, and no heat pump beats TH ÷ (TH − TL).
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