Abstract:
The objective of the research was to study the effects of intake valve timings
(Miller cycle), injection timings and ignition timings on the efficiencies and emissions
in a natural gas dedicated diesel engine. The engine was dedicated to natural gas
usage by modifying piston, fuel system and ignition system. The engine was installed
on a dynamometer and attached with various sensors and controllers. Intake valve
timing, engine speed, load, injection timing and ignition timing are main parameters.
The results of engine performances and emissions are present in form of graphs.
Miller Cycle without supercharging can increase brake thermal efficiency
1.08% and reduce brake specific fuel consumption 4.58%. The injection timing must
be synchronous with valve timing, speed and load to control the performances,
emissions and knock margin. Throughout these tested speeds, camshaft no.1 is
recommended to obtain high volumetric efficiency. Retard ignition timing can reduce
NOx emissions up to 14.5% while maintaining high brake thermal efficiency.