Carnot Cycle at Finite Power and Attainability of Maximal Efficiency Armen Allahverdyan

Download Presentation

Carnot Cycle at Finite Power and Attainability of Maximal Efficiency Armen Allahverdyan

Loading in 2 Seconds...

- 108 Views
- Uploaded on
- Presentation posted in: General

Carnot Cycle at Finite Power and Attainability of Maximal Efficiency Armen Allahverdyan

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Carnot Cycle at Finite Power and Attainability of Maximal Efficiency

Armen Allahverdyan

(Yerevan Physics Institute)

-- Introduction: heat engines, Carnot cycle

-- Non-equilibrium Carnot cycle

-- Analysis: PRL 2013.

-- Coauthors: Karen Hovhannisyan,

S. Gevorkian, A. Melkikh

Work-source

Hot bath

Cold bath

Cyclic engine

Power:

Work:

output / input

Efficiency:

Challenge: to make engines both powerful and efficient

B. Andresen, Angew Chem '11

U. Seifert, Rep. Prog. Phys. '12

Benenti, Casati, Prosen, Saito, arxiv:1311.4430

Carnot cycle: useless in practice: 4 times slow

Thermally isolated and slow

Isothermal and slow

Carnot = maximal efficiency

Non-equilibrium Carnot cycle

Engine: density matrix and Hamiltonian

Work-source and baths act separately easy to derive work and heat

Maximize W over dynamics

n+1 energy levels and the temperatures are fixed

Sudden changes are optimal

n degenerate states: energy concentration

optimized energy gaps

Work and efficiency

n>>1 number of levels

ln n >>1 number of particles

Relaxation time ?

Realistic

Ad hoc: system-bath (interaction) Hamiltonian is fine-tuned to system Hamiltonian

An example of fine-tuned system-bath Hamiltonian

bath: 2-level systems

there is

works for any

realistic

Unstructured data-base search (computationally complex)

Grover, PRL '97

Power zero

Farhi, Gutman, PRA '98

Vogl, Schaller, Brandes, PRA'10

ReduceW,resolve the degeneracy

Levinthal’s problem for protein folding

Zwanzig, PNAS '95

Conclusions

The reason of not reaching Carnot efficiencyfor realistic system-bath interaction is computational complexity

Protein models as sub-optimal Carnot engine

Non-reachability of Carnot efficiency at a large power is not a law of nature: there is a fine-tuned interaction that achieves this.