| In recent years,the automotive industry in the world has continued to develop rapidly,and many new technologies have emerged in an endless stream.However,for the entire automotive industry,the most important issue is always how to find a solution to the energy crisis.The public is increasingly concerned about the use of oxygenated fuels as a fuel additive in gasoline or other fossil fuels to address current fuel economy and environmental issues.Among various second-generation biofuels,alcohols have great potential for improving engine performance and reducing pollutant emissions.Alcohol biofuels,which have been widely studied in the field of gasoline engines,include butanol and ethanol.Among them,the advantages of n-butanol are extremely prominent,because its nature is very similar to that of gasoline,including n-butanol,which is easy to transport through pipelines.It has hydrophobicity,air-fuel ratio and gasoline's air-fuel ratio are very close,and energy density is nearly 30%higher than ethanol.Wait.However,the use of n-butanol in the engine has a production cost problem.The high cost and low production efficiency of recovering and dehydrating butanol from the ABE mixture have prohibited the industrial scale production of butanol[1],while acetone-butanol-ethanol?ABE?is an intermediate derived from the process of producing biobutanol.If ABE can be directly used as a substitute for gasoline to directly participate in clean combustion,the step of separating biobutanol can be omitted,thereby greatly reducing costs and improving effectiveness.The volume fraction of ABE is about 22-33%of acetone,62-74%of butanol,and 1-6%of ethanol?about 3:6:1?.Its spray and combustion characteristics are very similar to n-butanol,which can be guaranteed.Effectively reducing emissions under the premise of engine power,it has great potential as an alternative fuel for gasoline.In this paper,ABE and gasoline are mixed as a blending fuel.Before the experiment,acetone-butanol-ethanol is mixed at a volume ratio of 3:6:1 in natural biological fermentation,as a whole ABE solution,and then premixed with gasoline.ABE/gasoline blended fuel is used as the main experimental variable by changing the volume ratio of ABE in blended fuel.Other experimental parameters include excess air coefficient,ignition timing and speed load,etc.,under different working conditions,by changing ABE/gasoline blending.The effect of the volume ratio of ABE in the mixed fuel on the combustion characteristics and emission characteristics of the direct injection gasoline engine.The conclusions drawn in this paper include the following:?1?The effects of ABE/gasoline blending ratio on in-cylinder combustion,gas emissions and particulate emissions under different excess air coefficients were studied.It is found that the retardation period of ABE 100%is longer than that of other blending ratios,and the addition of a small proportion of gasoline to ABE can effectively improve this phenomenon.As the blending ratio of ABE increases,the main burning period is shortened,and the peak cylinder pressure and the maximum heat release rate are gradually increased.Due to the different nature of the ABE fuel,the difference in fuel injection caused a change in the intake state,and the intake efficiency was improved.At the same time,due to the fast flame velocity of the ABE laminar flow,the IMEP showed an upward trend.As the blending ratio of ABE increases,the CO emission decreases,the unburned HC emissions decrease,and the NOx emissions first decrease and then rise.The amount of particles will decrease rapidly with the addition of ABE.The accumulated particles will fall faster than the core particles.ABE itself can effectively oxidize the accumulated particles to the nucleus state.?2?The effects of ABE/gasoline blending ratio on in-cylinder combustion,gas emissions and particulate emissions at different ignition timings were studied.Under the ignition,the peak pressure and maximum heat release rate of ABE 100%are obviously less than ABE0%-ABE75%.Due to the longer lag period of ABE 100%,the ignition is delayed and burned in the work stroke,and the expansion work is lost.ABE0%-ABE75%obtains the best ignition advance angle around 15°CA BTDC,and the best ignition timing of ABE100%is about20°CA BTDC.ABE 100%is sensitive to changes in ignition timing in lean mode.With the increase of ABE blending ratio,IMEP gradually increases,CO emissions decrease,NOx emissions decrease first and then increase,and the sensitivity of HC emissions to ignition timing decreases.When the blending ratio of ABE is increased,the additional oxygen content is continuously oxidized during the conversion of the small-sized particles into the accumulated particles to maintain the nucleated particles.At each ignition timing,the total amount of particulates decreased significantly with increasing ABE.At the blending ratio of ABE 50%,the total particle concentration fluctuated with the change of ignition timing.The analysis is caused by the interaction between ABE evaporation endotherm and ABE oxygen carrying.?3?The effects of ABE/gasoline blending ratio on in-cylinder combustion,gas emissions and particulate emissions at different rotational speeds were studied.The peak value of cylinder pressure at different blending ratios of ABE,maximum heat release rate and IMEP are not sensitive to changes in rotational speed.As the proportion of ABE increases,CO emissions decrease,and NOx emissions first decrease and then rise.The HC emission varies with the speed of the cylinder by the combination of the in-cylinder temperature,the in-cylinder airflow and the crank angle.The particle size of the particles at 1200r/min has a three-peak distribution.As the blending ratio increases,the particle number decreases as a whole.The accumulated particles fall faster than the nucleus particles,and the total particle concentration increases first with the increase of the rotational speed.After the downward trend,the lowest value was reached at2100r/min.?4?The effects of ABE/gasoline blending ratio on in-cylinder combustion,gas emissions and particulate emissions under different loads were studied.With the increase of ABE blending ratio,the peak pressure of cylinder pressure gradually rises under medium and small load.The peak value of cylinder pressure rises first and then falls,the IMEP and maximum heat release rate increase,CO and HC emissions decrease,and NO emissions rise first and then rise.After blending ABE,the number of nanoscale particles increased sharply with increasing load.Under each load,the total amount of particulates decreased significantly with the addition of ABE. |
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