Friction and heat transfer across a finite temperature difference destroy exergy.
Lost work W_lost=T₀S_gen. Sources: friction, unrestrained expansion, mixing, heat transfer over finite ΔT and chemical reactions. Reducing them (insulation, closer temperature approach, recuperation) improves performance.
A throttling valve destroys exergy though energy is conserved.
Irreversibility is the source of lost work, and identifying it tells you where to make design changes that save energy.
Friction and heat transfer across a finite temperature difference destroy exergy.
Irreversibility is the source of lost work, and identifying it tells you where to make design changes that save energy.
Friction, unrestrained expansion, heat transfer across a finite temperature difference, and mixing of different substances.
It equals the ambient temperature times the entropy generated, which gives the work that could have been produced but was destroyed.
Typical applications include finding that a heat exchanger with a large temperature difference destroys most of the available work, reducing throttling losses in a steam system and identifying friction losses in a compressor as the main inefficiency.
Study "Exergy" first (topic 28 of 105 in Thermodynamics & Fluids). It covers the groundwork this topic builds on.
Gouy-Stodola theorem. Reversible limit zero. Compare components.
A throttling valve destroys exergy though energy is conserved.
The next topic is "Otto cycle", which builds directly on this one.
It is classed as Beginner in Thermodynamics & Fluids (topic 29 of 105). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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