Abstract
This study aims to obtain a strategy for optimizing the combination of injection conditions and combustion chamber geometry to achieve low unburned species emissions with high thermal efficiency and low NOx emission in a natural-gas dual fuel engine. Experiments were performed using a single-cylinder test engine with a common-rail injection system varying piston bowl diameter. The results showed that larger bowl diameter provides lower THC and CO emissions at earlier pilot injection timings in single-stage injection mode. In the case of two-stage pilot injection, larger bowl diameter improves THC and NOx emissions for smaller amount of first injection, on the other hand, piston bowl diameter has weak influence on exhaust emissions for larger amount of first injection.
