| Nowadays,China’s vehicle fuel consumption accounted for the proportion of oil consumption increases.Reducing oil consumption in the transportation has become an important focus of changes in energy consumption structure.Increasing the supply of new energy and renewable energy becomes the key to cut down crude oil consumption.Development of biofuels in many countries has become an important measure to improve energy security,reduce greenhouse gas emissions and address climate change.Preparation of isobutanol technology from biomass continues to progress and breakthroughs.It can provide target and power to transform biomass into liquid fuels and to use isobutanol gasoline blends for gasoline engine,and pollutant emissions will be reduced with using the blends fuel.Compared to the traditional fuel ethanol,biobutanol such as isobutanol offers advantages as gasoline substitutes because of their higher energy density and lower hygroscopicity.In addition,isobutanol can be blended with gasoline in higher concentrations,and is easy to be transported by pipeline with less corrosion.So isobutanol is a better suited replacement for gasoline compared to ethanol.The isomers of butanol include n-butanol,sec-butanol,tert-butanol,and iso-butanol(isobutanol),and isobutanol therein is an ideal gasoline blending components due to its highest octane number.As a gasoline blending component,isobutanol has a great potential for development and will be one of the possible ways to safeguard gasoline fuel supply in the future.In the paper,physical and chemical properties of isobutanol-gasoline blends was analyzed,including density,low heating value,10%volume fraction,kinematic viscosity,stochiometric air/fuel ratio,octane number,copper corrosiveness,oxygen percentages;the experimental investigation was conducted to evaluate and compare the power performance,fuel economyand and regulated emission using isobutanol-gasoline blends in gasoline engine without modification;meanwhile,the unregulated emissions of formaldehyde,acetaldehyde,methanol,ethanol,propanol,isobutanol and benzene were analyzed in the gasoline engine;vehicle experiment was investigated using isobutanol-gasoline blends without vehicle modification,and warm idle stability,emissions,and climbing capacity of the vehicle were tested and compared with different isobutanol-gasoline blends and pure gasoline.(1)The objective of the current investigation was to explore the influence on fuel properties of blending gasoline with isobutanol having contents of 10,20,30 40,50,60,70,80,90 vol%with pure gasoline fuel.The physical and chemical properties of isobutanol-gasoline blends were obtained experimentally based on standards and codes and were calculated theoretically.There was no phase separation in isobutanol-gasoline blends at specific temperatures(-10～30 ℃),and isobutanol and gasoline could be blended in every ratio volume,and isobutanol-gasoline blends with different isobutanol volume had good intersolubility.The density of the blends increased gradually with increased volume fractions of isobutanol,the densities of isobutanol and gasoline were similar,which made no big influence on utilization in gasoline engine.The low heating value(LHV)of the blends decreased gradually with an increased volume proportion of isobutanol,but LHV of isobutanol was similar to gasoline comparing with methanol and ethanol.’The 50%distillation temperature,90%distillation temperature and final boiling point temperature of the blends decreased with increase of volume fractions of isobutanol,which is beneficial to shorten heating-up time of gasoline engine,decrease carbon deposition in engine cylinder and improve the rate of complete fuel combustion.The kinematic viscosity of the blends increased gradually with an increasing volume fraction of isobutanol.The kinematic viscosities of isobutanol were measured as nine times higher than those of gasoline,and isobutanol addition is not good for using blends at low temperature environment.The stoichiometric air/fuel ratio of the blends decreased gradually and linearly with an increase in the isobutanol fraction,so that the fuel is burnt more completely with reducing emissions,but the output power of engine will be declined.The octane number of the blends increased gradually with an increasing volume fraction of isobutanol,isobutanol addition will help reduce gasoline engine knocking conditions.The oxygen percentages of the blends increased with an increasing isobutanol fraction,which will help reduce CO and HC emissions,and the improve fuel combustion efficiency.Blends showed no copper corrosion,and the isobutanol-gasoline blends showed the best corrosion resistance,and gasoline storage facilities need not preservative change.There was linear relationship between ratio of isobutanol and change of blends properties such as density,LHV,stochiometric air/fuel ratio,octane number,copper corrosiveness,oxygen content.Oxygen content of the blends were to be influenced obviously by ratio of isobutanol,copper corrosiveness was not to be influenced.Density,octane number,oxygen percentages of blends increased gradually with increased volume fractions of isobutanol.Low heating value,stochiometric air/fuel ratio of blends decreased gradually with increased volume fractions of isobutanol.There was exponential relationship between ratio of isobutanol and change of blends properties such as kinematic viscosity and 10%distillation temperature,which were increased gradually with increased volume fractions of isobutanol.This paper could provide some based data for utilization of isobutanol-gasoline blends in gasoline engine.(2)The experimental investigation was conducted to evaluate and compare the power performance including power and torque,fuel economy including brake specific fuel consumptions,equivalent brake specific fuel consumptions,and energy consumptions(BSFC,EBSFC,and EC)and exhaust emission including CO,C02,THC,and NOx of pure gasoline and isobutanol-gasoline blended fuels with 10,20,30,40,and 50 vol%isobutanol in a four-cylinder gasoline engine without modification.The results showed that BSFC increased with the isobutanol content under full-throttle conditions when the engine speeds were 2000 rpm(low speed),3000 rpm(medium speed),and 4000 rpm(high speed).At different engine speeds,the BSFC decreased with increasing engine torque.Compared with the BSFC,all of the EBSFC curves were closer together,indicating better fuel economy characteristics.At some engine speeds and torques,the EBSFC values of different blended fuels were almost the same.Compared with the BSFC and EBSFC,all of the EC curves were closer together.Unlike the BSFC and EBSFC,the EC of the blended fuels did not increase with the isobutanol content,and the EC of pure gasoline was higher than that of the blended fuels overall.The results indicate that the combustion efficiency of the isobutanol-gasoline blends was higher than that of pure gasoline in a gasoline engine.The CO emissions decreased with increasing isobutanol content at a given engine speed and torque,especially at low torque.The CO2 emissions decreased with increasing isobutanol content at a given engine speed and torque.At different engine speeds,the CO2 emission of all of the fuels increased with the engine torque.At a given engine torque,the CO2 emissions increased with the engine speed.The THC emissions decreased with increasing isobutanol content at a given engine speed and torque.At different engine speeds,the THC emissions of all of the fuels increased with the engine torque.At a given engine torque,the THC emissions decreased with increasing engine speed.The NOx emissions decreased with increasing isobutanol content at a given engine speed and torque;however,the exhaust gas temperature also increased with the isobutanol content,and further analysis is required.Power and torque were decreased with increase of isobutanol proportion in blends,but decrease was less than 5%.The engine external characteristic experiment was done and compared.The results showed that engine power and torque of the isobutanol-gasoline blends were about the same performance while burning pure gasoline.The brake specific fuel consumptions and the equivalent specific fuel consumption of the blends were increases slightly.The energy consumption rate of the pure gasoline was higher than the isobutanol-gasoline blends.The CO and THC emissions were reduced compared with the pure gasoline,and the CO2 and NOx emissions were decreased sightly.The engine afterburners were appeared because of high octane number of blends,and the exhaust temperature was increased.120 isobutanol-gasoline blends was gotten by synthesizes evaluation methods with considering indexes of power,torque,BSFC,EBSFC,EC,CO,CO2,THC,and NOx based on fuzzy mathematics.(3)The exhaust gas was collected simultaneously,and 7 kinds of unregulated emissions were qualitatively and quantitatively analyzed based on gas chromatography methods.The Influence of isobutanol proportion,speed and load on unregulated emissions was gotten.The result shown that ethanol was the biggest emissions in 7 kinds of unregulated emissions;other alcohols emissions were also bigger such as methanol,propanol and isobutanol.Ethanol emissions was decreased with increase of isobutanol proportion in blends,and isobutanol emissions was increased.Large increase was in the magnitude of ethanol and methanol emissions change with output torque increased,and no large increase in other emissions.Total alcohols emissions were decreased with increase of isobutanol proportion in blends,and with the isobutanol proportion increased,the magnitude of alcohol emissions reduced more obvious.However,isobutanol emissions were increased with isobutanol proportion.For example,isobutanol emissions were increased from 5.1 times to 7.0 times,and from 6.1 times to 12.0 times bigger than pure gasoline when burning 140 and 150,respectively.Emissions of formaldehyde,acetaldehyde and benzene were decreased significantly with increase of isobutanol proportion in blends.(4)Vehicle experiment was investigated using isobutanol-gasoline blends without vehicle modification.Warm idle stability,emissions,and climbing capacity of the vehicle were tested and compared with different isobutanol-gasoline blends and pure gasoline.The result shown that quality evaluation of blends(110-150)at warm idle speed was better;under double idle speed situation(high idle speed and idle speed),THC emission,NOx emission and excess air coefficient were decreased after increase with increase of isobutanol content in blends;CO emission of 110 and 120 were bigger than other blends at double idle speed;it was good quality evaluation at 1st gear for four kinds of blends except 110;it was good quality evaluation for speed increase,dynamic quality and climbing capacity for three kinds of blends except 140 and 150. |
PDF Full Text Request