Table of Contents
Physics Research International
Volume 2011 (2011), Article ID 496057, 7 pages
Research Article

Effects of Pressure Drops on the Performance Characteristics of Air Standard Otto Cycle

Academic Institute for Training Arab Teachers (AITAT), Beit Berl Academic College, Doar Beit Berl 44905, Israel

Received 16 September 2010; Accepted 25 May 2011

Academic Editor: Frank Tsui

Copyright © 2011 Mahmoud Huleihil. 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.


The effects of pressure drops on the performance characteristics of the air standard Otto cycle are reported. The pressure drops are assumed as constant values independent of the engine size. It has been shown that the pressure drops to about 60% of the maximum pressure in the ideal cycle (Curto-Risso et al., 2008). Three different models are studied: constant pressure model, reversible adiabatic expansion model and polytropic expansion model. The findings of this study show that, at this level of pressure drop, the maximum efficiency of the Otto cycle is reduced by 15% approximately based on the constant pressure model. The combined effect of pressure drop with other modes of irreversibility, for example, internal irreversibility and heat leaks, could reduce the maximum efficiency into very low values (approximately 30%). The reversible adiabatic model predicts reduction of 13% in efficiency at 40% pressure drop levels but at the price of zero power production. On the other hand, the polytropic expansion model predicts 40% reduction in efficiency for the same level of pressure drop (40%). All three models show that the power output is very sensitive to pressure drop.