Linear Irreversible Thermodynamics, Efficiency and Coefficient of Performance of Thermal Brownian Motors in Tight Coupling

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Date

2007-07

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Addis Ababa University

Abstract

We analytically study a thermal Brownian motor and calculate exactly the Onsager's coe±cients in equilibrium and steady state conditions. We show that the reciprocity relation holds and the determinant of the Onsager's matrix vanishes. Such a condi- tion implies that the device is built with tight coupling. This tells us why Carnot's e±ciency can be achieved in the limit of in¯nitely slow velocities (quasistatic pro- cess). We also ¯nd the e±ciency and the coe±cient of performance for our model at these conditions using Onsager's coe±cients. The e±ciency and the coe±cient of performance that we found using the tools of LIT is exactly the same as the Carnot's e±ciency and coe±cient of performance. Also we ¯nd the e±ciency (at maximum power) and the maximum coe±cient of performance of the Brownian refrigerator to be exactly identical with the the corrosponding results of Curzon - Alhborn and Carnot's refrgerator for perfectly tight coupling model

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Linear Irreversible Thermodynamics

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