Summarizing and Interpreting Aircraft Gaseous and Particulate Emissions Data (2008) / Chapter Skim
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Appendix D - Additional Supporting Material for Chapter 5: Review of the Data from Measurement Campaigns
Appendix D - Additional Supporting Material for Chapter 5: Review of the Data from Measurement Campaigns
Pages 41-59
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From page 41... ...
The gaseous emissions of the APEX engines exhibited the anticipated trends with respect to engine power condition and the measured values were similar to the ICAO certification values (see Section D.2 for more details on the gas-phase measurements)
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power conditions are emphasized in Table D1.2 since these are the set points used in ICAO certification data. EIs for take-off power conditions are only available in certain cases due to the difficulty in operating stationary aircraft at fullrated thrust.
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power conditions are emphasized since these are the set points used in ICAO certification data.
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Measured particle distributions typically exhibited two distinct modes, one corresponding to non-volatile particles and peaking at roughly the same diameters observed in the 1-m [3-ft] samples, and the other occupied by freshly nucleated sulfur and organic particles peaking at <12 nm.
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Average number-based emission indices at take-off measured for six aircraft engine families during the Delta-Atlanta Hartsfield Study.
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D.1.8 Chemical Composition of Aviation Particles As a complement to aviation particle physical characterization, the APEX studies included measurements of particle 46 Date Ambient condition min max avg std dev % Deviation 9/27/2004 Temperature (°C)
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Mean particle diameter, number-based emission index, and mass-based emission index as a function of engine power for the -2C1, -3B1, and -7B22 models of the CFM56 class of engines.
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Figure D1.6. Ranges of measured number-based emission index for engines emissions sampled in the near field plume.
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At idle, aviation PM seems to be predominantly organic material, a result of the relatively lower combustor efficiencies at low power conditions. At climb-out and take-off, combustor efficiency is greater than 99%, very little UHC exits the engine, and the particles contain roughly equal amounts of sulfate and organic material.
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Likewise, aircraft engines operate at power conditions not tabulated in the ICAO databank. In fact, the runway studies conducted at Atlanta-Hartsfield airport (Herndon et al.
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, take-off (93%) , and intermediate power conditions including 15%, 45%, and 65% rated thrust.
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From page 52... ...
power conditions are emphasized in Table D2.2 to facilitate comparison to ICAO certification data. EIs for take-off power conditions are only available in certain cases due to the difficulty in operating stationary aircraft at full-rated thrust.
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i The 7% thrust setting was not studied for this engine -- data measured at 8% rated thrust. j The CJ6108A thrust is lower than the ICAO certification limit.
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• Discrepancies between APEX EI NOX and ICAO EIs generally occurred only when the actual fuel flow rate deviated from the ICAO value. D.2.2 Gas-Phase Measurement Reliability and Sources of Systematic Error In addition to reproducibility, absolute measurement accuracy is also important.
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. Gas turbine engines operating at low power conditions are an exception, as they emit a substantial amount of NOX as NO2.
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Less than 10% of the total NOX is emitted as NO2 at high power conditions for the turbofan engines. • The turbojet engine, which is shown for contrast, emits a substantial fraction of the NOX as NO2 at all power conditions.
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EI HCHO increases with decreasing fuel flow rate. The relationship between fuel flow rate and EI HCHO accounts for about onethird of the observed dependence of EI HCHO on ambient temperature.)
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D.2.5 Potential Use of APEX Data and the ICAO LTO Cycle to Generate Emissions Inventories The APEX data can be used in conjunction with airport operations data to generate airportwide emissions inventories. The depth of chemical information and the wider range of operational conditions included in the APEX data set allow it be used to generate more comprehensive emissions inventories than is possible with ICAO data.
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From page 59... ...
In the meantime, the effects of ambient conditions, especially ambient temperature, and power conditions are clear. Figure D2.5 captures data variability graphically for total UHC emissions.
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