Combustion And Emission Characteristics Of Tetrahydrofuran/Ethanol/Diesel Blended Fuel

Diesel engines are the main emissions sources of SOOT and nitrogen oxides.The overuse of conventional diesel has also led to a global shortage of fossil resources.Using alternative fuels and exhaust gas recirculation technology(EGR)is a key way to realize the efficient and clean combustion of d iesel engine.Due to its advanced production technology and high oxygen content,ethanol received widespread attention.But the miscibility of ethanol/diesel blending is poor,it is difficult to ascend the blending ratio of ethanol.Tetrahydrofuran as an additive can solve this problem,and tetrahydrofuran is also an oxygenated fuel.This paper mainly studies the THF/ethanol/diesel fuel blends combustion and emission characteristics.The engine used in the test was a modified single-cylinder electrically controlled high pressure common rail diesel engine,and four test fuels were E20,E20T10,E30T10 and D100,respectively representing the volume fraction of ethanol/tetrahydrofuan/diesel as follows:20/0/80%,20/10/70%,30/10/60%and0/0/10%.The combustion and emission characteristics of the blended fuels were investigated under three conditions:(1)changing the EGR rate,(2)changing the fuel injection timing,and(3)changing the speed and load.The results showed that:(1)Under the condition of low EGR rate,increasing the mixing ratio of oxygenated fuel will increase the ignition delay,the maximum cylinder pressure,the maximum heat release rate and the maximum pressure rise rate,and the heat release will be more concentrated.CO emissions will be redu ced,but THC and NO_xemissions will be increased.Under the condition of high EGR rate,increasing the mixing ratio of oxygenated fuel is more likely to cause misfire,and the NO_x emissions gradually turns into a negative correlation with the proportion of oxygenated fuel.When the EGR rate is greater than 30%,the E30T10 has extremely low SOOT and NO_x emissions at the same time.(2)With the delay of fuel injection timing,the ignition delay of the four test fuels increases,and the cylinder pressure,the maximum pressure rise rate and the indicated thermal efficiency all decrease,but the peak heat release rat e first decreases and then increases.The THC and CO emissions of the four test fuels all increase,while the NO_x emissions decrease.The SOOT emissions of E20,E20T10 and E30T10all increase,but the trend becomes slower,while the SOOT emissions of E30T10decrease under three conditions when injection timing is-4°CA,-2°CA and 0°AC,respectively.(3)With the increase of engine speed or load,all of the ignition delay,the peak cylinder pressure,the peak heat release rate,the maximum pressure rise rate and the indicated thermal efficiency of the four test fuels decrease.E30T10 has the highest THC emission and NO_x emission,but its SOOT emissions is the lowest under all conditions in this chapter.In this paper,the mixing ratio of tetrahydrofuran/ethanol/diesel blended fuel and three working conditions were studied as variables.The results have reference significance for the further application and research of tet rahydrofuran as diesel addition.