Study Of Spray Characteristics And Engine Performance Of Palm Oil-diesel-ethanol Micro-emulsions

Energy is the driving force for the development of human society and an important foundation for the progress of human society.With the increasing shortage of petroleum resources and the enhanced environmental awareness of people,it is urgent to develop automotive clean alternative fuels.As a kind of biofuel,vegetable oil has wide source.It is not subject to geographical restrictions and can be adapt to local conditions.Because vegetable oil can be produced and consumed at the same place,it does not require long-distance transportation.In addition,the production technology of vegetable oil is easy to master and the investment is small.Most oil-producing plants have a short growth cycle and are easy to be grown.Vegetable oil is used in a variety of applications and also an economical alternative to diesel fuels.In this paper,palm oil was selected as the research object.The micro-emulsified fuels of palm oil-diesel-ethanol have been prepared at different blending ratios.The main physicochemical properties of micro-emulsified fuels were measured using national standard method.High-speed camera system and Malvern laser particle analyzer were performed to study and compare the spray characteristics between micro-emulsified fuels and diesel.Based on the comprehensive consideration of the physicochemical and spray properties,the micro-emulsified fuels prepared from palm oil were used on the engine experiment.The conclusions are in the following.Compared to the micro-emulsified fuels,diesel has a larger spray cone angle in the experiment.For the PD30 and PD50 groups,the spray cone angle increased with the blending amount of ethanol increasing at different injection pressures.When the ethanol blending amount is the same,it is obvious that the spray cone angle of the PD30 group is larger than that of the PD50 group.There is a close relationship between the spray penetration distance and spray cone angle of fuel.The larger the spray penetration distance,the smaller the corresponding spray cone angle.Diesel has the smallest Sauter mean diameter,while the Sauter mean diameter of PD50E10 is the largest.For the PD30 and PD50 groups,the Sauter mean diameter decreases with the blending amount of ethanol increasing.In addition,when the ethanol blending amount doesn’t change,the Sauter mean diameter increases as the amount of palm oil blended in the base oil increasing.Under the same injection pressure,for five fuels the small-diameter particles within 20 μm account for the majority.And,the peaks of five fuels all appear at around 10 μm.It illustrates the atomization effects of five fuels are well.The PD50E30 has the highest fuel consumption rate,while the diesel fuel consumption rate is the smallest.The closest to the diesel is PD30E10.The effective thermal efficiency of micro-emulsified fuels is higher than that of diesel.At small load,the emission of CO from micro-emulsified fuels is significantly higher than that of diesel.While it is almost the same or lower than that of diesel at medium and high load.At 1800 r/min,the emission of NOx of the micro-emulsified fuels is higher than that of diesel.However,at 2200 r/min the NOx emission of the micro-emulsified fuels from PD50 groups is higher than that of the diesel;the NOx emission of the micro-emulsified fuels from PD30 groups is lower than that of the diesel.The soot emissions and concentration of ultrafine particles of the micro-emulsified fuels are lower than these of diesel.For the micro-emulsified fuels,the nuclear mode particles account for the majority in the ultrafine particles;while the diesel has both the nuclear mode and the accumulation mode.As the speed increases,the concentration of ultrafine particles of diesel and micro-emulsified fuel decreases.As the load increases,the peak of the ultrafine particle number concentration increases,and the peak diameter of the particles first increases and then decreases.