Table of Contents
Journal of Thermodynamics
Volume 2012, Article ID 246914, 7 pages
Research Article

Maximum Power Point Characteristics of Generalized Heat Engines with Finite Time and Finite Heat Capacities

1Department of Physical Sciences, Indian Institute of Science Education and Research Mohali, Sector 81, Manauli, Mohali, Punjab 140306, India
2Elite Course Theoretical and Mathematical Physics, Ludwig Maximillian University, D-80333 Munich, Germany

Received 19 September 2012; Revised 27 November 2012; Accepted 27 November 2012

Academic Editor: M. A. Rosen

Copyright © 2012 Abhishek Khanna and Ramandeep S. Johal. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We revisit the problem of optimal power extraction in four-step cycles (two adiabatic and two heat-transfer branches) when the finite-rate heat transfer obeys a linear law and the heat reservoirs have finite heat capacities. The heat-transfer branch follows a polytropic process in which the heat capacity of the working fluid stays constant. For the case of ideal gas as working fluid and a given switching time, it is shown that maximum work is obtained at Curzon-Ahlborn efficiency. Our expressions clearly show the dependence on the relative magnitudes of heat capacities of the fluid and the reservoirs. Many previous formulae, including infinite reservoirs, infinite-time cycles, and Carnot-like and non-Carnot-like cycles, are recovered as special cases of our model.