Comparative performance evaluations of various optimization functions for irreversible Otto cycles

Kodal A. I., Kodal A.

THERMAL SCIENCE AND ENGINEERING PROGRESS, vol.15, 2020 (SCI-Expanded) identifier identifier


A comparative performance analysis for irreversible Otto cycles has been carried out with consideration of overall and effective power loss for various optimization functions available in the literature. Basically, maximum power, maximum power density, ecological coefficient of performance and the ecological function are taken into consideration, and their optimal operating conditions were compared with respect to each other in terms of various engine parameters. The irreversible cycle model operating between two isothermal high and low temperature heat reservoirs is considered and combined with various irreversibilities for power loss analysis. In the irreversible model, non-isentropic compression and expansion, heat leak through the cylinder head and power loss due to friction are taken into account. Effects of engine volumetric efficiency, engine speed, friction and extreme cycle temperature on the overall performance for the respective optimal operating conditions have been investigated. It is seen that the overall power loss increases for increasing engine speed, decreasing volumetric efficiency, increasing friction coefficient and decreasing high temperature of the cycle. It is also observed that the maximum power conditions have higher overall power loss but lower internal irreversibility losses among the considered optimization functions.