Experimental Study Of The Effects Of2,5-dimethylfuran Addition On Combustion And Emissions In A Diesel Engine

Facing the increasing significant energy issues and global warming caused by theconsuming of the fossil fuel, people begin pay more and more attention to the biofuelswhich is renewable and carbon-neutral. As the second generation of biofuels,2,5-dimethylfuran （DMF） have extensive resources and proper physiochemicalproperties to be used in diesel engines, which can be a very promising alternative fuelfor engine. Theoretically some physiochemical properties of DMF like low cetanenumber, fuel oxygenated and low boiling point can help to improve the combustionand emissions of diesel engine with low temperature combustion. While there is noreport referring to the research of DMF in diesel engine yet.This research was conducted on a diesel engine equipped with electronic controlhigh pressure common rail. To begin with, the effects of different DMF ratio on thecombustion, performance, regulated and non-regulated emissions of diesel engine atmiddle-high EGR rate was investigated, and optimization is also made according tothe results. It shows that the ignition delay is prolonged, heat release rate increases,the in-cylinder maximum pressure and maximum pressure rise rate （MPRR） increaseswith the increase of DMF proportion in the blends. At the same combustion phase,with the addition of DMF, the indicated thermal efficiency decreases slightly at lowEGR rate while increases slightly at high EGR rate. The proportion of NO₂, which ismore poisonous in NO_x, increases with the increase of DMF proportion in the blends,while the proportion of CH₄in THC decreases and the HCHO increases under theseconditions. As for the40%DMF fuel, the proper postpone of CA50would effectivelydecrease the MPRR and reduce the NO_xemissions while guarantee the ultra-low sootemissions and an acceptable thermal efficiency, however, the THC and CO emissionswould be increased.Then, the influence of each DMF physiochemical properties on the combustionand emissions of the engine was analyzed by comparing several designed blend fuels.The results show that, the cetane number of DMF is the dominating factor that affectsthe combustion characteristics. The reduction of soot emissions of Diesel-DMFblends becomes more obvious with the increase of EGR rate, especially for Soot-Bump region. When the ratio of DMF is20%, the low cetane number is theprimary reason to reduce the soot emissions, followed by the effects of fuel oxygen,while the volatility, viscosity and fuel dilution effects of DMF have little effects underthese conditions. The NO_xemissions of Diesel-DMF blends are higher than purediesel, while these effects decrease with the increase of EGR rate. There is littledifference of THC and CO emissions between the Diesel-DMF blends and pure dieselover all the EGR range. It is also found that the changes of cetane number will havemore influence on the combustion and emissions of diesel engine at lower cetanenumber and higher EGR rate.