Investigation of low-temperature performance, combustion and emission characteristics of biodiesel fuels in reactivity controlled dual fuel diesel engine

With the development of the world economy, the demand for crude oil is growing rapidly. Limited fossil fuel availability and air pollution have drawn a continuously increasing attention to the study of alternative fuels and combustion systems. In order to improve combustion efficiency and reduce the emissions in internal combustion engines, scientific researches focus on the development of new combustion modes and the optimization of the current technology systems. Low temperature combustion (LTC) can be regarded as reliable strategies for the reduction of emissions and the improvement of fuel economy. Reactivity controlled compression ignition (RCCI) is one of important LTC strategies. The RCCI combustion is achieved by utilization of the separate injection system with low-reactivity fuel introduced through intake process and high-reactivity fuel with the direct injected into cylinder, so that moderate combustion can be realized. In this study, the effect of RCCI on a diesel power generator was experimentally investigated by using safflower oil biodiesel-diesel blends. Ethanol and gasoline are low reactivity fuels that were premixed as PFI by rates of 30% and 50% of total mass fuel consumption of the engine. The important combustion, performance and emission indicators of the engine were deeply investigated under various conditions. The results showed that combustion efficiency and engine performance were improved by utilizing ethanol and gasoline RCCI. On the other hand, RCCI increased the brake specific fuel consumption values at low engine loads while the values were decreased at high engine operations. Consequently, NOx emissions considerably decreased while CO and HC emissions were slightly increased but they were still quite low.