膜法富氧进气降低点燃式发动机冷起动排放

研究了富氧进气对火花点火发动机冷起动排放的影响.试验在一台四行程、空冷125 mL单缸电控喷射火花点火LPG发动机上进行.试验中分别为发动机供应φO2=21%,23%,25%的进气,实时测量发动机冷起动阶段最初60 s内过量空气系数λ及HC、CO和NOx的排放.试验结果表明,发动机采用富氧进气后,HC和CO的排放量显著降低.与φO2=21%氧浓度进气比较,φO2=23%进气时,冷起动最初60 s内HC与CO排放累计量分别降低46%和54%;φO2=25%进气时,分别降低65%和80%.当进气φO2由23%提高到25%后,HC和CO排放减少量不多,仅为36%和26%,而NOx排放增加明显.因此,使用富氧进气降低冷起动排放时,φO2控制在23%左右为宜.

Reducing Cold-Start Emissions of an Spark-Ignition Engine Using Membrane-Based Oxygen-Enriched Intake Air

This article investigated the effects of oxygen-enriched intake air on cold-start emissions from an SI engine fueled with LPG.The experiments were carried out on a four-stroke,air-cooled,single-cylinder,125 mL spark-ignition(SI) engine with EFI system.The engine was supplied respectively with intake air containing 21%(oxygen level of ambient air),23% and 25% oxygen(by volume).The time-resolved(emissions) data were recorded and analyzed during the initial 60 s period after starting.The test results indicate that the engine-out HC and CO emissions are considerably reduced using oxygen-enriched intake air compared to ambient air.When using 23% and 25% oxygen-enriched intake air,the HC emissions are reduced by about 46 % and 65%,and CO by about 54% and 80%,respectively.It is notable that when the oxygen content of intake air increases from 23% to 25%,the reductions in both HC and CO emissions are marginal,but NO_x emission increases significantly.About 23% oxygen level is appropriate when oxygen-enriched intake air is used to reduce the cold-start emissions.