Experimental Study On The Effects Of Gasoline Fuel Characteristics On Vehicle Performance

It is significant for the improvement of gasoline quality and formulating appropriate gasoline standard in China by further investigating the effects of gasoline fuel property on vehicle fuel economy,power and emission performance.Therefore,experiments were carried out on a chassis dynamometer to study the effects of hydrocarbon content,the physic-chemical properties of gasoline and oxygenated additives on vehicle fuel economy,power and emission performance.Firstly,two light duty passenger vehicles,which are equipped with a gasoline direction injection(GDI)and a port fuel injection(PFI)engine respectively,are employed to investigate the different gasoline surrogate components on the vehicle fuel economy,emission,and acceleration performance over the NEDC test cycle.Three kinds of gasoline surrogate fuels with the same research octane number of 92,including a blending fuel with 92% vol.iso-octane and 8% vol.n-heptane(PRF92),and two kinds of three components gasoline surrogates(TRF50 and ORF50)which are formulated by replacing toluene or diisobutylene with iso-octane in PRF92 respectively,are used in the experiment.The test results show that the fuel consumption for both vehicles can be reduced by adding toluene and diisobutylene compared to iso-octane;The NOx can be reduced by adding diisobutylene for both vehicles,while it is on the contrary by adding toluene;Increased CO and reduced THC are observed by adding diisobutylene and toluene for GDI vehicle,while both transient CO and THC emission before 100 s in NEDC cycle are increased for PFI vehicle;In terms of particulate matter emissions,the particulate matter(PM)and particle number(PN)are increased by adding toluene for GDI vehicle,while adverse trend are observed by adding diisobutylene for GDI vehicle;Adding toluene or diisobutylene is helpful to reduce the PM for PFI vehicle,while it is adverse for PN emission.In terms of acceleration performance,the acceleration duration for GDI vehicle can be shortened by adding toluene or diisobutylene,but adding toluene makes the acceleration duration increased for PFI vehicle.On the basis of the above work,the physic-chemical properties of eleven kinds of gasoline from different companies with different RONs are analyzed and experiments are conducted on both two vehicles to investigate the effects of aromatic content,olefin content,octane number,volatility,density,calorific value and other physicochemical properties of the gasoline on fuel economy,emission and acceleration performance.The test results indicate that it shows correlation among vapor pressure,density,T50,aromatic volume fraction and volume heat value.It was found that aromatic hydrocarbon content,olefin content and physicochemical parameters of gasoline product have not decisive influence on the fuel consumption and emissions of the vehicles.There is a negative correlation between the acceleration duration of the GDI vehicle and the calorific value of the gasoline,while the acceleration duration of the PFI vehicle prolonged with T50.Finally,four typical oxygenated fuels,including methanol,ethanol,n-butanol and 2,5-dimethylfuran(DMF)are chosen to mix with RON92 gasoline with 10%,20% and 30% volume ratios to formulate different oxygenated blends,and then experiment is conducted on a GDI vehicle to investigate the effects of different oxygenated fuels on vehicle performance and emission.The results show that the fuel consumption and emissions of the vehicle during stable operation at medium and high speeds can be reduced by blending all four oxygenated fuels,but there is no much improvement during stable operation at low speed and UDC phases.N-butanol shows best performance in reducing fuel consumption among these four fuels.PN and PM have a great improvement when 10%(v/v)methanol,ethanol,n-butanol or DMF were blended,PN and PM were only slightly lowerd as the blending ratio increases to 30%(v/v).The acceleration duration can be shorten by blending each of four oxygenated fuels,and the higher blending is,the shorter acceleration duration will be.In summary,there has almost no obvious improvement in improving vehicle performance and emission by further reducing olefins and aromatic content from national V stage gasoline.It is beneficial to improve the vehicle fuel economy and emission performance by blending a certain proportion of methanol,ethanol,n-butanol or DMF,and the blending ratio of methanol and ethanol should be less than 10%(v/v),but the blending ratio of butanol and DMF can be extended to 30%(v/v).