Coupled autonomous thermal machines and efficiency at maximum power
Abstract
We show that coupled autonomous thermal machines, in the presence of three heat reservoirs and following a global linearirreversible description, provide a unified framework to accommodate the variety of expressions for the efficiency at maximum power (EMP). The efficiency is expressible in terms of the Carnot efficiency of the global set up if the intermediate reservoir temperature is an algebraic mean of the hot and cold temperatures. We give an explanation of the universal properties of EMP near equilibrium in terms of the properties of symmetric algebraic means. For the case of broken time reversal symmetry, a universal second order coefficient of 6/49 is predicted in the series expansion of EMP, analogous to the 1/8 coefficient in the timereversal symmetric case.
 Publication:

arXiv eprints
 Pub Date:
 December 2021
 DOI:
 10.48550/arXiv.2112.00660
 arXiv:
 arXiv:2112.00660
 Bibcode:
 2021arXiv211200660J
 Keywords:

 Condensed Matter  Statistical Mechanics;
 Quantum Physics
 EPrint:
 Revtex42,7 pages, 2 figures, 1 table