Comparison of Otto cycle and Atkinson cycle with optimized Intake cam profile of a turbocharged spark ignition engine

an over-expanded spark ignited engine was investigated in this work via engine test with a design constrained, mechanically actuated Atkinson cycle mechanism. A conventional ۴-stroke spark-ignited turbocharged engine with a compression ratio of ۹.۲ and peak power ۱۱۲ kW was selected for the baseline engine. Starting with a validated ۱D engine simulation model which included calibration of the in-cylinder pressure and SI turbulent combustion model, investigations of the Atkinson engine including intake cam optimization was investigated. Full range of speed and load sweep was conducted to compare the BSFC, fuel consumption, torque between baseline and Atkinson cycle engine with valve timing optimization were also investigated. Results from the study indicate that average fuel consumption rate goes down after optimization, reduction rate of brake specific consumption indicating the fuel economy is improved under this operating condition.

Keywords:

Turbocharged SI Engine , Optimization cam profile , Fuel Economy , BSFC