Influence of Jet Fuel Composition on Aircraft Engine Emissions: A Synthesis of Aerosol Emissions Data from the NASA APEX, AAFEX, and ACCESS Missions

We statistically analyze the impact of jet fuel properties on aerosols emitted by the NASA Douglas DC-8 (Tail No. N817NA) CFM56-2-C1 engines burning 15 different aviation fuels. Data were collected for this single engine type during four different, comprehensive ground tests conducted over the past decade, which allow us to clearly link changes in aerosol emissions to fuel compositional changes. It is found that the fuel aromatic and sulfur content most affect the volatile aerosol fraction, which dominates the variability (but not necessarily the magnitude) of the number and volume emissions indices (EIs) over all engine powers. Meanwhile, the naphthalenic content of the fuel determines the magnitude of the nonvolatile number and volume EI as well as the black carbon mass EI. Linear regression coefficients are reported for each aerosol EI in terms of these properties, engine fuel flow rate, and ambient temperature and show that reducing both fuel sulfur content and naphthalenes to near-zero levels would result in roughly a 10-fold decrease in aerosol number emitted per kilogram of fuel burned. This work informs future efforts to model aircraft emissions changes as the aviation fleet gradually begins to transition toward low-aromatic, low-sulfur alternative jet fuels from biobased or Fischer–Tropsch production pathways.本研究针对美国国家航空航天局（NASA）道格拉斯DC-8型飞机（尾号N817NA）搭载的CFM56-2-C1型发动机，统计分析了15种不同航空燃油的物性对其排放气溶胶的影响。本研究的数据来源于过去十年间针对该单一型号发动机开展的四次全面地面测试，借此可清晰建立气溶胶排放变化与燃料组分变化之间的关联。研究发现，燃料的芳烃与硫含量对挥发性气溶胶组分影响最为显著，该组分主导了全功率工况下气溶胶数量与体积排放指数（Emissions Indices, EIs）的变化幅度，但不一定决定其数值大小。与此同时，燃料的萘系组分含量决定了非挥发性气溶胶的数量与体积排放指数，以及黑碳质量排放指数的数值大小。本研究给出了基于上述燃料物性、发动机燃油流量与环境温度的各气溶胶排放指数的线性回归系数，结果显示，若将燃料硫含量与萘系组分含量降至接近零的水平，每千克燃料燃烧所排放的气溶胶数量将减少约一个数量级。本研究可为后续构建航空排放变化预测模型的工作提供参考：随着航空机队逐步转向采用生物质基或费托合成（Fischer–Tropsch）工艺生产的低芳烃、低硫替代喷气燃料，该模型可用于预测航空排放的变化情况。