Experimental Study On The Influence Of Unconventional Additives And Physical And Chemical Properties Of Fuel Oil On The Performance Of Light Passenger Vehicle

With the increasing number of cars and stricter emission regulations,reducing fuel consumption and improving emissions has always been the focus of gasoline engine research.It is of great significance to understand the influence of physical and chemical properties of gasoline on fuel economy,power performance and emission of gasoline engine,so as to improve gasoline quality and establish reasonable new gasoline standard in China.The use of additives to improve gasoline quality does not need to change the refining process of gasoline or gasoline engine structure,and has the advantages of flexibility and simplicity.Therefore,the effects of several unconventional additives on the physical and chemical characteristics of commercial gasoline were studied in this paper,and the effects of the physical and chemical parameters of gasoline and 11 unconventional additives on the fuel economy and emissions of light passenger vehicles were studied on the chassis ergometer.In addition,due to the complexity of gasoline components and the diversity of fuel physical and chemical properties,it is complicated to analyze the impact of gasoline components and physical and chemical properties on the performance of light passenger vehicles,so principal component analysis is introduced to study this.In view of the obvious shortcomings of widely used fuel additives such as methyl tert-butyl ether(MTBE)and ethanol,in order to search for better gasoline additives,this paper first studied the effects of unconventional additives on the physical and chemical properties of 92# and 95# gasoline.The additives mainly include alcohols,esters,ethers,phenols and amines,including isobutanol,ethyl tert-butyl ether,isopropyl ether,aniline,diethylamine,dimethyl carbonate,sec-butyl acetate,isobutyl acetate,dimethyl malonate,p-methyl phenol and p-tert-butyl phenol.The results show that the evaporation of 95# gasoline is more sensitive to additives than 92# gasoline.The selected alcohols,ethers,amines and esters have great influence on the T50 of gasoline,while the phenolic additives have great influence on the T90 of gasoline.The effects of additives on Reid vapor pressure(RVP)of 92# gasoline and 95# gasoline were the same,and the RVP decreased.However,compared with 95# gasoline,the RVP of 92#gasoline is more affected by additives.The influence trend of various additives on Driveability Index(DI)of 92# gasoline and 95# gasoline is the same,but the influence degree of different additives on DI of the two kinds of gasoline is different.In order to ensure good driving performance,especially cold start performance and warm engine performance,European and American countries created the concept of driving index to represent the volatile performance of gasoline.The alcohol and ether additives used will decrease DI,and the phenolic additives will increase DI.The influence trend of various additives on RON of 92# gasoline and 95# gasoline is the same,which will increase RON.However,compared with 95# gasoline,the RON of 92# gasoline is more affected by additives.Aniline and p-methylphenol have significant effects on RON of gasoline.Only 1.5% aniline and 3% p-methylphenol could increase RON by 3.6% and3%,respectively.On the basis of the above work,the effects of two different grades of gasoline(92#and 95#)added with isobutanol,ethyl tert-butyl ether,isobutyl acetate,aniline,pmethylphenol and p-tert-butyl phenol on NEDC fuel consumption and emission in a light passenger vehicle with PFI engine were studied.In order to reflect the impact of fuel on vehicle emissions,the three-way catalytic converter was removed during the test and raw emission data was used.The test results show that all the additives can reduce the fuel consumption per 100 km for 92# gasoline.In NEDC cycle,adding 12%isobutanol can reduce fuel consumption by 3.33%.The additives had little effect on the fuel consumption of 95# gasoline,and the addition of ETBE and isobutyl acetate even increased the fuel consumption of 95# gasoline.For 92# gasoline and 95# gasoline,the effect of additives on CO emission in UDC cycle representing urban conditions is higher than that in EUDC cycle representing suburban conditions.For 92# gasoline,all additives can reduce CO emissions.Adding 3 vol% p-methyl phenol can reduce CO emission by 5.43%.For 95# gasoline,the additive has no significant effect on CO emission.The addition of aniline and p-methylphenol even increased CO emission.For92# gasoline,the effect of additives on THC emission in UDC cycle is higher than that in EUDC cycle.Except isobutyl acetate,all the other additives reduced THC emission of 92# gasoline.For 95# gasoline,most additives lead to elevated THC emissions.In the NEDC cycle,all the additives lead to an increase in NOx emissions from 92#gasoline.For 95# gasoline,isobutanol,isobutyl acetate and p-methyl phenol can reduce NOx emissions.All additives can improve the acceleration performance of 92# and 95#gasoline.Most of the additives improved the acceleration performance of 92# gasoline by more.In general,additives have a greater impact on the performance of 92# gasoline on PFI vehicles.Therefore,when selecting additives,we should take into account the type of base oil.The additives optimize the performance of gasoline with low octane number.Finally,34 oil products including 92# additive gasoline,95# additive gasoline and commercial gasoline were used to carry out NEDC cycle tests on PFI vehicles.The physical and chemical properties of fuel affect each other,and also affect the performance of vehicles,so the analysis is complicated.Therefore,using principal component analysis method,12 original variables were reduced to 3 variables,namely,the first principal component score,the second principal component score and the third principal component score,to analyze the physical and chemical properties of oil.The first principal component was negatively correlated with vapor pressure,and positively correlated with density,initial distillation point temperature,5% evaporation temperature,10% evaporation temperature,aromatic content,final distillation point,RON.The second principal component was negatively correlated with the content of heavy aromatic hydrocarbons and 90% evaporation temperature,but positively correlated with 50% evaporation temperature.The third principal component score was positively correlated with olefin content.In UDC cycle,EUDC cycle and NEDC cycle,the first principal component score can describe the three economic indexes of fuel consumption per 100 km,equivalent fuel consumption per 100 km and CO2 emission well.The third principal component score can better describe NOx emission,and the principal component score can describe the index,which is not a clear result.In conclusion,the effects of additives on the physical and chemical properties of different grades of gasoline are different.Compared with 92# gasoline,evaporation of95# gasoline is more sensitive to additives,while RVP and RON of 92# gasoline are more sensitive to additives.Almost all of the six unconventional additives improved the economy and certain emissions of PFI vehicles.Principal component score can better reflect the original physical and chemical properties of oil,and can better describe the economic performance and emission performance of automobile.Therefore,principal component score can be regarded as a new index to describe the influence of physical and chemical properties of oil on vehicle performance.