title: Carnot cycle at finite power: attainability of maximal efficiency.
abstract: We want to understand whether and to what extent the maximal (Carnot) efficiency for heat engines can be reached at a finite power. To this end we generalize the Carnot cycle so that it is not restricted to slow processes. We show that for realistic (i.e., not purposefully designed) engine-bath interactions, the work-optimal engine performing the generalized cycle close to the maximal efficiency has a long cycle time and hence vanishing power. This aspect is shown to relate to the theory of computational complexity. A physical manifestation of the same effect is Levinthal's paradox in the protein folding problem. The resolution of this paradox for realistic proteins allows to construct engines that can extract at a finite power 40% of the maximally possible work reaching 90% of the maximal efficiency. For purposefully designed engine-bath interactions, the Carnot efficiency is achievable at a large power.
authors: Yerevan Physics Institute, Alikhanian Brothers Street 2, Yerevan 375036, Armenia.
authors: Armen E
authors: AE
authors: Allahverdyan
authors: Karen V
authors: KV
authors: Hovhannisyan
authors: Alexey V
authors: AV
authors: Melkikh
authors: Sasun G
authors: SG
authors: Gevorkian