Numerical analysis of a compression ignition engine for CHP applications powered in the dual-fuel mode with syngas and biodiesel

In the present energy scenario, distributed combined heat and power (CHP) generation using biomass gasification is attracting increasing interest as a prospective way to provide energy to remote districts by using locally available renewable sources. The use of syngas obtained from biomass gasification in internal combustion engines is surely feasible at the micro and small scale although it is to be considered that the quality of the producer gas is considerably poorer compared to traditional fuels in terms of calorific value and laminar flame speed. This implies the need for proper modifications and optimization of engines in order to make them able to run efficiently and with low environmental impact. Present work is focused on the development of a numerical model of a compression ignition engine fueled in the dual-fuel mode with syngas and biodiesel, aimed to highlight the main changes to the combustion process related to the use of syngas. The numerical approach is used to characterize engine performance and to highlight the effect of the biomass moisture content on power output and main pollutants emission. The used extended coherent flamelet model for turbulent combustion is preliminary validated on the basis of experimental results for engine pressure cycles measured under biodiesel fueling.