Title: The effects of variable specific heats of working fluid on the performance of an irreversible Otto cycle

Authors: Yanlin Ge, Lingen Chen, Fengrui Sun, Chih Wu

Addresses: Postgraduate School, Naval University of Engineering, Wuhan 430033, P.R. China. ' Postgraduate School, Naval University of Engineering, Wuhan 430033, P.R. China. ' Postgraduate School, Naval University of Engineering, Wuhan 430033, P.R. China. ' Mechanical Engineering Department, US Naval Academy, Annapolis, MD 21402, USA

Abstract: The performance of an air-standard Otto cycle with variable specific heats of working fluid and heat resistance and friction irreversible losses is analysed by using finite-time thermodynamics. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are derived by detailed numerical examples. Moreover, the effects of variable specific heats of working fluid on the irreversible cycle performance are analysed. The results show that the effects of variable specific heats of working fluid on the cycle performance are obvious, and it should be considered in practice cycle analysis. The results obtained in this paper may provide guidance for the design of practice internal combustion engines.

Keywords: finite-time thermodynamics; friction irreversible losses; heat resistance; Otto cycles; performance optimisation; variable specific heats; working fluid; cycle performance; internal combustion engines; engine design.

DOI: 10.1504/IJEX.2005.007255

International Journal of Exergy, 2005 Vol.2 No.3, pp.274 - 283

Published online: 27 Jun 2005 *

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