Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

Gas Turbine Engine Emissions—Part I: Volatile Organic Compounds and Nitrogen Oxides

[+] Author and Article Information
Michael T. Timko

 Aerodyne Research Inc., 45 Manning Road, Billerica, MA 01821-3976timko@aerodyne.com

Scott C. Herndon, Ezra C. Wood, Timothy B. Onasch, Megan J. Northway, John T. Jayne, Manjula R. Canagaratna, Richard C. Miake-Lye

 Aerodyne Research Inc., 45 Manning Road, Billerica, MA 01821-3976

W. Berk Knighton

Department of Chemistry, Montana State University, P.O. Box 173400, Bozeman, MT 59717-3400

J. Eng. Gas Turbines Power 132(6), 061504 (Mar 19, 2010) (14 pages) doi:10.1115/1.4000131 History: Received April 13, 2009; Revised July 07, 2009; Published March 19, 2010

The potential human health and environmental impacts of aircraft gas turbine engine emissions during normal airport operation are issues of growing concern. During the JETS/Aircraft Particle Emissions eXperiment(APEX)-2 and APEX-3 field campaigns, we performed an extensive series of gas phase and particulate emissions measurements of on-wing gas turbine engines. In all, nine different CFM56 style engines (including both CFM56-3B1 and -7B22 models) and seven additional engines (two RB211-535E4-B engines, three AE3007 engines, one PW4158, and one CJ6108A) were studied to evaluate engine-to-engine variability. Specific gas-phase measurements include NO2, NO, and total NOx, HCHO, C2H4, CO, and a range of volatile organic compounds (e.g., benzene, styrene, toluene, naphthalene). A number of broad conclusions can be made based on the gas-phase data set: (1) field measurements of gas-phase emission indices (EIs) are generally consistent with ICAO certification values; (2) speciation of gas phase NOx between NO and NO2 is reproducible for different engine types and favors NO2 at low power (and low fuel flow rate) and NO at high power (high fuel flow rate); (3) emission indices of gas-phase organic compounds and CO decrease rapidly with increasing fuel flow rate; (4) plotting EI-CO or volatile organic compound EIs against fuel flow rate collapses much of the variability between the different engines, with one exception (AE3007); (5) HCHO, ethylene, acetaldehyde, and propene are the most abundant volatile organic compounds present in the exhaust gases that we can detect, independent of engine technology differences. Empirical correlations accurate to within 30% and based on the publicly available engine parameters are presented for estimating EI-NOx and EI-NO2. Engine-to-engine variability, unavailability of combustor input conditions, changing ambient temperatures, and complex reaction dynamics limit the accuracy of global correlations for CO or volatile organic compound EIs.

Copyright © 2010 by American Society of Mechanical Engineers
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Figure 1

Comparison of 1 m and >15 m EI-NO2 data for an engine, which showed a large discrepancy (CJ6108A/N616NA), and one that did not (RB211-535E4-B/N74856)

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Figure 2

NOx speciation for (a) RB211-535E4-B and (b) CJ6108A engines. ICAO data points (▶◀) are shown for reference.

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Figure 3

Emission indices of several representative volatile organic compounds measured during the engine tests (a) EIs for formaldehyde, benzene, and naphthalene plotted as functions of engine power for a CFM56–3B1 engine (N353SW). (b) Relative ratios of important volatile organic compound emissions for several representative engines operating at idle for the measurement suite available to us.

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Figure 4

Emission indices of gaseous pollutants plotted as functions of fuel flow rate for APEX-2/3 engines: (a) NO; (b) the NO2/NOx emission index ratio; (c) acetaldehyde, a representative volatile organic compound. Lines are shown to guide the eye and are not intended to convey physical significance.

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Figure 5

EIm-NOx data for the CFM56 engines: (a) EIm-NOx plotted against power condition; (b) EIm-NOx plotted against fuel flow rate to remove engine-to-engine variability for CFM56 type engines

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Figure 7

Comparison of (a) CO and (b) HCHO measurements with the correlations of Eqs. 7,8, respectively. Each data point is the average of all available replicate measurements at a given set of conditions (i.e., sample rake, power, etc.). Error bars are defined in the text. The CJ6108A (△) is an outlier in both regressions, as is the first plane in APEX-3 (▲, N14324). Values of best-fit parameters are listed in the figure and in Table 6.

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Figure 6

Comparison of nitrogen oxide measurements to the Eq. 6 fit: (a) NOx; (b) NO2. Each data point is the average of all available replicate measurements at a given set of conditions (i.e., sample rake, power, etc.). Error bars are defined in the text. EI-NO2 was divided into two regimes based on power, ≤45% and >45%. Values of best-fit parameters are listed in Table 6. CJ6108A (not shown) is an outlier in the NO2 analysis.




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