School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, 20 Oxford St., Cambridge, Massachusetts 02138, USA.
Environ Sci Technol. 2011 Aug 15;45(16):7075-82. doi: 10.1021/es200897h. Epub 2011 Jul 20.
Given the predicted growth of aviation and the recent developments of alternative aviation fuels, quantifying methane (CH(4)) and nitrous oxide (N(2)O) emission ratios for various aircraft engines and fuels can help constrain projected impacts of aviation on the Earth's radiative balance. Fuel-based emission indices for CH(4) and N(2)O were quantified from CFM56-2C1 engines aboard the NASA DC-8 aircraft during the first Alternative Aviation Fuel Experiment (AAFEX-I) in 2009. The measurements of JP-8 fuel combustion products indicate that at low thrust engine states (idle and taxi, or 4% and 7% maximum rated thrusts, respectively) the engines emit both CH(4) and N(2)O at a mean ± 1σ rate of 170 ± 160 mg CH(4) (kg Fuel)(-1) and 110 ± 50 mg N(2)O (kg Fuel)(-1), respectively. At higher thrust levels corresponding to greater fuel flow and higher engine temperatures, CH(4) concentrations in engine exhaust were lower than ambient concentrations. Average emission indices for JP-8 fuel combusted at engine thrusts between 30% and 100% of maximum rating were -54 ± 33 mg CH(4) (kg Fuel)(-1) and 32 ± 18 mg N(2)O (kg Fuel)(-1), where the negative sign indicates consumption of atmospheric CH(4) in the engine. Emission factors for the synthetic Fischer-Tropsch fuels were statistically indistinguishable from those for JP-8.
鉴于航空业的预计增长以及替代航空燃料的最新发展，量化各种飞机发动机和燃料的甲烷（CH(4)）和氧化亚氮（N(2)O）排放比，可以帮助约束航空对地球辐射平衡的预计影响。在 2009 年首次替代航空燃料实验（AAFEX-I）期间，从 NASA DC-8 飞机上的 CFM56-2C1 发动机中量化了基于燃料的 CH(4)和 N(2)O 排放指数。JP-8 燃料燃烧产物的测量表明，在低推力发动机状态（怠速和滑行，或分别为 4%和 7%的最大额定推力）下，发动机以平均±1σ的速率排放 CH(4)和 N(2)O，分别为 170±160mg CH(4)(kg 燃料)(-1)和 110±50mg N(2)O(kg 燃料)(-1)。在更高的推力水平下，对应更大的燃料流量和更高的发动机温度，发动机废气中的 CH(4)浓度低于环境浓度。在最大额定推力的 30%至 100%之间燃烧的 JP-8 燃料的平均排放指数为-54±33mg CH(4)(kg 燃料)(-1)和 32±18mg N(2)O(kg 燃料)(-1)，其中负号表示发动机消耗大气中的 CH(4)。合成费托燃料的排放因子在统计学上与 JP-8 没有区别。
