Measurement of Gaseous HAP Emissions from Idling Aircraft as a Function of Engine and Ambient Conditions (2012) / Chapter Skim
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Appendix C - Exhaust Probe Sampling Techniques
Appendix C - Exhaust Probe Sampling Techniques
Pages 77-84
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From page 77... ...
2010) probe and a traditional heated metal transfer line quantified differences in the hydrocarbon compounds and attributed them to the sampling line In order to ensure that the HAP species measured in this work are indicative of the true exit plane and were not modified by the sampling method, the test protocol investigated the hydrocarbon profile using different sampling methods during the DAL 2009 test.
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From page 78... ...
From top to bottom at the right are the standard gas probe, the dilution probe, and the CQQ probe. Mobile Probe Staged Stationary 1-meter Probe Test or n engine Test or n Engine MDW'09 1 CFM56-3 3 CFM56-7 DAL '09 DAL '09 1 CFM56-7 CFM56-7 1 Particle Probe (4)
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From page 79... ...
The probe rake was integrated into the Missouri Science and Technology probe stand, which was placed directly behind engine 2 of the test aircraft and did not noticeably move when the engine was ramped up to 10% of the rated thrust. Minor modifications were required for the chemical quick quench probe tip, which previously had not been used for aircraft exhaust measurements.
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From page 80... ...
iii. Chemical Quick Quench Probe The chemical quick quench involves nitrogen dilution at the probe tip as well as a seven fold pressure drop effected in order to minimize probe chemistry and to expedite the transfer of exhaust from the engine exhaust to the sampling instrumentation (the volumetric flow rate increased by a factor of seven following the pressure drop)
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From page 81... ...
The emission indices are actually approximately 1⁄3 of the values of those with nominal engine bleed during the CQQ test and are relatively static when compared to those of HCHO during the other tests. An independent measurement of HCHO provided by the PTR-MS corroborates the HCHO results shown in Figure C-5.
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From page 82... ...
The reduction in pressure employed via the quick quench probe more faithfully transports low vapor pressure compounds through the sampling lines. Assessment of reliable sampling is evaluated by examining the integrity of Figure C-5.
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From page 83... ...
The heated gas probe fails on both criteria set forth for reliable sampling. As discussed previously, the formaldehyde concentrations measured using this probe are altered substantially from that obtained by other sampling methods.
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From page 84... ...
The chemical quick quench probe might be somewhat excessive, however, for what is required. While doing staged testing at Chicago Midway airport in the winter of 2010, a dilution probe with a Teflon transfer line was implemented and seemed to minimize chemical reactions occurring in the sample line.
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