Abstract:
Dual fuel operation in compression ignition engines is an effective way to reduce the
NOx emission. Within the certain range of fuel premixing ratio (PR), the dual fuel operation in
CI-engines results in improved thermal efficiency. The dual fuel CI-engine has relatively
higher cyclic variations in comparison to conventional CI-engine which limits the range of fuel
premixing in dual fuel CI-engine. The cyclic variations in air-fuel ratio, cylinder wall
temperature, and residual gas fraction are the major factors, which governs the variations in
combustion parameters. The cyclic variations in combustion need to control for stable engine
operation. The present study estimates the cyclic air-fuel ratio, cylinder wall temperature, and
residual gas fraction from the measured in-cylinder pressure data of dual-fuel CI-engine. The
experiments are performed on a modified single cylinder CI-engine equipped with a separate
port fuel injector and its controller to operate an engine in dual fuel mode. In this study, 1500
consecutive engine cycles are recorded, and air-fuel ratio, cylinder wall temperature, and the
residual gas fraction is estimated for each cycle. Pressure moment method is used to estimate
the cyclic air-fuel ratio. The cyclic cylinder wall temperature is calculated by determining the
inversion angle. The cyclic variations are analyzed using statistical methods.
