Regensburg 2016 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 27: Poster - Statistical Physics, Critical Phenomena, Brownian motion

DY 27.9: Poster

Tuesday, March 8, 2016, 18:15–21:00, Poster C

Optimal performance under limited control of periodically driven, stochastic heat engines — •Michael Bauer¹, Kay Brandner^1,2, and Udo Seifert¹ — ¹II. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany — ²Department of Applied Physics, Aalto University, 00076 Aalto, Finland

We investigate the performance of periodically driven, stochastic heat engines under optimal driving in the linear response regime. The Onsager coefficients for such machines obeying Fokker-Planck dynamics have recently been developed and illustrated with an overdamped Brownian particle, where the driving protocol allows full control on the particle [1].

Here, we are interested in the performance of such heat engines if only a limited number of degrees of freedom can be externally controlled. In a case study, we examine a heat engine consisting of an underdamped Brownian particle in a magnetic field, where the kinetic degrees of freedom cannot be controlled. We find expressions for the efficiency in analogy to the performance of thermoelectric devices and define an adequate figure of merit. In the absence of a magnetic field, more general results are obtained if the control functions are assumed to be given by the eigenfunctions of the adjoint Fokker-Planck operator. We recover the expressions of the case study and obtain a condition for the attainability of Carnot efficiency.

[1] K. Brandner, K. Saito, and U. Seifert, Phys. Rev. X 5, 031019 (2015)