Performance Analysis of A Spark Ignition (SI) Otto Cycle (OC) Gasoline Engine Under Realistic Power (RP) And Realistic Power Density (RPD) Conditions

Abstract

This study presents performance optimization of an Otto cycle (OC) gasoline engine using new criteria named as realistic power (RP) and realistic power density (RPD) conditions based on finite-time thermodynamics (FTT). The effects of design and operating parameters such as cycle temperature ratio, cycle pressure ratio, friction coefficient, engine speed, mean piston speed, stroke length, inlet temperature, inlet pressure, equivalence ratio, compression ratio and bore-stroke length ratio on the performance parameters such as effective efficiency, effective power and power density have been examined. Moreover, the energy losses have been determined as fuel's energy and they have been illustrated based on incomplete combustion, friction, heat transfer and exhaust output by using figures. Realistic values of specific heats have been used depend on temperature of working fluid. The results obtained demonstrated that the engine performance increases with increasing some parameters such as cycle temperature ratio, cycle pressure ratio, inlet pressure; with decreasing some parameters such as friction coefficient, inlet temperature. However, the engine performance could increase or decrease with respect to different conditions for some parameters such as engine speed, mean piston speed, stroke length, equivalence ratio and compression ratio. The results of this study could be used an engineering tool by Otto cycle engine designers.