Effects of the three dual-fuel strategies on performance and emissions of a biodiesel engine

Three dual-fuel strategies, i.e. Strategy S (syngas-biodiesel), Strategy U (upgraded syngas-biodiesel), and Strategy D (DME-biodiesel), for utilization of syngas and biodiesel from biomass wastes in internal combustion engines have been proposed in this study. To compare both the combustion and emission performance of the three strategies, an integrated KIVA4-CHEMKIN CFD platform was constructed implementing a newly combined reaction mechanism. Effects of three dual-fuel strategies have been compared against each other in terms of indicated power, NOx and soot emission. At different engine loads, it was found that the indicated power of all strategies increased with the increasing supplement ratio. Strategy S and Strategy U predict higher indicated power than Strategy D at the high engine load, while lower indicated power than Strategy D at the low engine load. As regards to the NOx emission, an increase in the fuel supplement ratio increases the NOx emission (g/kWh) for both Strategy S and Strategy U at high engine loads, while decreases the NOx emission (g/kWh) due to the enhanced indicated power. Strategy D has relatively higher NOx emission (g/kWh) than Strategy S and Strategy U at all loads. With the increase in fuel supplement ratio, the soot emission generally shows a decreasing trend at all engine loads for all strategies, and Strategy D emits less soot than Strategy S and Strategy U in the cases of high fuel supplement ratio (>0.4) for all engine load conditions.