Optimized Power And Efficiency Of Feynman’s Ratchet As A Heat Engine

Abstract

The maximum power of Feynman’s ratchet as a heat engine ( ) and the corresponding efficiency ( ) are investigated by optimizing both the internal parameter and the external load. When a perfect ratchet device (no heat exchange between the ratchet and the paw via kinetic energy) works between two thermal baths at temperatures , its efficiency at maximum power is found to be

, where

is Carnot’s efficiency, which is slightly higher than the value √

√ obtained by Curzon and Ahlborn for macroscopic heat engines. It is also slightly larger than the result

obtained by Schmiedl and Seifert for stochastic heat engines working at small temperature difference and the maximum power of Feynman’s ratchet as a heat engine in this model is

, e is natural exponent and is a constant with dimension second inverse

. By developing objective function for optimization of this thesis engine model, fixing some parameters of the objective function plot objective function ( ̇) versus external parameter (z) then extract the value of external parameter (z) from peak point of the plot to optimize power and efficiency of Feynman’s ratchet as a heat engine numerically. Hence numerically, maximum power is , efficiency at maximum power is , the optimized power is and the optimized efficiency is . The overall performance of this work is a proximately greater than unity