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The Carnot operates reversibly between only two reservoirs by using adiabatic expansion and compression steps—not heat transfer—to swing between the temperature extremes. During the isothermal steps, …

The equation $dS=\frac{dQ}{T}+dS_\mathrm{irr}$ is a great example of combining two aspects of entropy: Entropy is the "stuff" that shifts upon heat transfer. When we look at ways to transfer energy ( …

I understand how Carnot's theorem implies that irreversible heat engines must be no more efficient than reversible one's, but it is less clear why they need to be less efficient Irreversibility mean …

Only in this way can reversibility be maintained, as entropy is produced any time energy moves down a gradient (in temperature or some generalized force), but reversibility implies zero entropy production … The (unrealizable) limit of the engine operating at $T= T_\mathrm{RHS}$ corresponds to reversibility. …

Work comes in a variety of flavors (pressure–volume, force–length, stress–volumetric strain, surface tension–surface area, electric field–polarization, voltage–charge, magnetic field–magnetization, et …

Thermodynamic reversibility is an idealization we use when we don’t care to calculate the entropy production or when we wish to explore the limit of low friction and high efficiency. … Reversibility in the sense of a chemical reaction is different; it means we have a hope of running the reaction in the opposite direction. …

I think the question is asking how—if the Carnot engine's original state was at $T_\mathrm{high}$, corresponding to the initial temperature of a high-temperature finite body—can the engine return to t …

The free expansion isn’t reversible because the gas flows down a pressure gradient (that arises when you remove the piston). Any energy flow down a gradient generates entropy. In contrast, during the …

Now, it stands to reason that reducing either to zero would provide us with reversibility, but if we block the flux, then process evolution is precluded, and if we have no gradient, then there's no driving …

Edit: To avoid confusion, the authors aren’t referring to thermodynamic reversibility (i.e., zero entropy generation). This never occurs in real life. …

so in other words, this equation will work no matter what, be it open or closed system, reversible or irreversible process. No; the equation $\delta q=mc_XdT$ describes the temperature change at con …

The idealization of zero entropy generation and reversibility is nonetheless sometimes useful. …

And in any case, we could come arbitrarily close to reversibility with careful design and by running a process very slowly, so an analysis assuming reversibility isn't completely ludicrous. …

Note, however, that we could approach reversibility by conducting processes nearly in balance, with very low friction. … Doesn’t this connote reversibility?” Not in a global thermodynamic sense, which is usually the context of thermodynamic (ir)reversibility discussions. …

Entropy flows during heat transfer, but entropy is not conserved; it is also generated from nothing whenever energy flows down a gradient in an intensive property (such as pressure, temperature, chemi …