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Ultrafine particulate jet aircraft emissions depending on fuel sulfur content and contrail processing
J. Aemsol Sci. Vol. 29. Suppl. I. pp. S5614562.
0
Pergamon
1998
1998 Published by Elsevier Science Ltd. All rights reserved Printed in Great Britain 0021.8502/98
$19.00 + 0.00
ULTRAFINE PARTICULATE JET AIRCRAFT EMISSIONS DEPENDING ON FUEL SULFUR CONTENT AND CONTRAIL PROCESSING
F. SCHRijDER, A. PETZOLD and B. K&RCHER
Deutsches Zentrum fiir Luft- und Raumfahrt (DLR), Institut fi,ir Physik der Atmosphke, D-82234 Wessling, Germany
KEYWORDS Ultrafine Particles; Volatile Jet Exhaust Aerosol; Soot; Aircraft Emissions
The impact of aircraft-produced aerosols upon chemistry and climate has recently received considerable attention. Particles emitted by aircraft jet engines and formed in-situ in young exhaust plumes can potentially induce the formation of ice clouds (contrails), modify the microphysical properties of existing cirrus clouds, and provide sites for heterogeneous chemical reactions. Characterization of particle size distribution and composition is one key step in assessing and quantifying these impacts. During the SULFUR 5 experiment particulate exhaust products of Rolls Royce/SNECMA M45H Mk501 turbofan engines of the DLR research aircraft ATTAS have been measured in the size range between 5 nm and about 20 urn. Here, we report findings concerning the fine mode volatile aerosol particle emissions related to the mass of burned fuel (Ns: Dp > 5 nm; N14 : Dp cl4 nm) as measured by modified condensation particle counters (CPC, TSI type 3010/376OA, [Mertes et al., 1995, Schrijder and Strom, 19971). Measurements have been carried out 0.1-3 km behind ATLAS at cruising altitudes around 9-10 km with high- (3000 ppm) and low sulfur containing fuel (20 ppm) as well as for contrail forming (“wet“, p=286hPa, T=2 19K, RH=33%) and non-contrail forming (“dry“, p=357hPa, T=23 1K, RH=46%) conditions. More experimental details are given in Schrijder et al.( 1998). Figure 1 comprises Ns- and N,d-data for the high sulfur (H)- and low sulfur (L) cases, grouped together for dry exhaust (D)- and contrail forming (W) conditions, respectively. Horizontal bars at about 1.7E15 [#/kg] (D) and lE15 [#/kg] (W) mark the fraction of non-volatile (=soot) particles (see Petzold et al., this issue) with just a minor contribution to Ns and N14, respectively. Starting with the drv exhaust plume case and high sulfur fuel burned (HD) we report as much as Ns = 1.4E17 [#/kg] (almost) volatile aerosols while N,d-values increase from 4E15 to 9E15 in between about Is-10s plume age. At the same time low sulfur fuel yields at least ten times lower Nrvalues, increasing by a factor of four (5E15 to 2E16 [#/kg]) while Nt4 remains constant around 2.4E15. Constant Nr, and doubling of N14 for the HD case implies mean particle diameters DM > 5 nm already 1 second past exit. On the other hand (the LD case) unchanged N,b-values and strongly increasing Ns are consistent with a smaller particle mode growing from below 5 nm into the CPC detection range during the Is-10s period. Suggesting Du = 10 nm for the HD-case the volume fraction of new generated particulate matter (estimated H$SOJ&O solution droplets, 1: 1 volume ratio) reaches about 150 ppmv which corresponds to about 2.5% conversion of fuel sulfur to particulate H$!i04” For the LD-case (Ns=2E16 and estimated DM = 5 nm) the conversion rate is most likely higher. However, since considerable amounts of condensed matter are likely to exist below the CPC-detection range and the potential involvement of other condensing species in new particle production, certainly masked in the HD case, cannot be excluded, a further understanding of the LD-case requires a detailed physiochemistry model study. S561
5362
Abstracts
of the 5th International
Aerosol Conference
1998
Measurements under contrail forming Contrail Dry Exhaust conditions (W, right figure) generally yielded a factor of 2 less particle concentrations: Ni4 = 1.2E15 (LW), N14 = 5E15 (HW); Ns = 5E15 (LW) as well as N5 = 7E16 (HW) both with a decreasing tendency between 2 and 20 seconds with consistent plume and age = calculations of coagulation scavenging onto contrail ice crystals (lpm in -2 diameter). These crystals must also contain significant fractions of the Z %.I primary emitted soot aerosol, since even the “soot level“ is clearly lower in the WZ compared to the D-case and the aerosol sampling system is insensitive to supermicron particles like ice crystals. Thus, the discrepancy in the soot fractions yields evidence for the involvement of non-volatile aerosol as condensation nuclei in the contrail forming process. this work shows that In summary, 1 10 10 1 sulfur content fuel increasing Plume Age [s] significantly increases the emission index of ultrafine volatile aerosols of jet that illustrates also aircraft. It coagulation scavenging of fine mode Figure 1: (Mostly) volatile particle abundance vs plume particles takes place onto contrail ice age measured in the dry exhaust plume (0) and under crystals and that - consequently - an contrail forming conditions (W). Shown are Ns (open evaporating contrail will release an symbols) and N14 (filled symbols) for the L- (triangles) “cloud-processed” aerosol. In already and H-cases (circles). Lines indicate sulfur-induced contrast to dry aircraft exhaust products particle growth (0. trends fitted to data) and particle this aerosol is characterized by lower scavenging onto contrail ice (W, calculated trends). CN-concentrations (condensation nuclei) but - most likely - a larger amount of Aitken-mode soot particles containing significant quantities of highly hygroscopic, liquid H2S0JI-120-coating. This property makes them potential candidates for CCN (cloud condensation nuclei) rather than unprocessed soot emissions. ACKNOWLEDGEMENTS We thank the pilots and the stuff of DLR Flight Department for essential contributions experiment; further U. Schumann and Reinhold Busen for valuable discussions on this work.
to a successful
REFERENCES 1995: Particle detection efficiency curve of the TSI-3010 CPC as a function of the temperature difference between saturator and condenser, Aeros. Sci. Technol. 23: 257-261 Schriider, F. and J. StrSm, 1997: Aircraft measurements of sub micrometer aerosol particles (>7nm) in the midlatitude free troposphere and tropopause region, Atmos. Research, 44.333-356 Schriider, F., B. Kiircher, A. Petzold, R. Baumann, R. Busen, C. Hiill, and U. Schumann, 1998: Ultratine aerosol particles in aircraft plumes: In-situ observations, submitted to GRL Mertes, S., F. Schriider,
and A.Wiedensohler,
0
Pergamon
1998
1998 Published by Elsevier Science Ltd. All rights reserved Printed in Great Britain 0021.8502/98
$19.00 + 0.00
ULTRAFINE PARTICULATE JET AIRCRAFT EMISSIONS DEPENDING ON FUEL SULFUR CONTENT AND CONTRAIL PROCESSING
F. SCHRijDER, A. PETZOLD and B. K&RCHER
Deutsches Zentrum fiir Luft- und Raumfahrt (DLR), Institut fi,ir Physik der Atmosphke, D-82234 Wessling, Germany
KEYWORDS Ultrafine Particles; Volatile Jet Exhaust Aerosol; Soot; Aircraft Emissions
The impact of aircraft-produced aerosols upon chemistry and climate has recently received considerable attention. Particles emitted by aircraft jet engines and formed in-situ in young exhaust plumes can potentially induce the formation of ice clouds (contrails), modify the microphysical properties of existing cirrus clouds, and provide sites for heterogeneous chemical reactions. Characterization of particle size distribution and composition is one key step in assessing and quantifying these impacts. During the SULFUR 5 experiment particulate exhaust products of Rolls Royce/SNECMA M45H Mk501 turbofan engines of the DLR research aircraft ATTAS have been measured in the size range between 5 nm and about 20 urn. Here, we report findings concerning the fine mode volatile aerosol particle emissions related to the mass of burned fuel (Ns: Dp > 5 nm; N14 : Dp cl4 nm) as measured by modified condensation particle counters (CPC, TSI type 3010/376OA, [Mertes et al., 1995, Schrijder and Strom, 19971). Measurements have been carried out 0.1-3 km behind ATLAS at cruising altitudes around 9-10 km with high- (3000 ppm) and low sulfur containing fuel (20 ppm) as well as for contrail forming (“wet“, p=286hPa, T=2 19K, RH=33%) and non-contrail forming (“dry“, p=357hPa, T=23 1K, RH=46%) conditions. More experimental details are given in Schrijder et al.( 1998). Figure 1 comprises Ns- and N,d-data for the high sulfur (H)- and low sulfur (L) cases, grouped together for dry exhaust (D)- and contrail forming (W) conditions, respectively. Horizontal bars at about 1.7E15 [#/kg] (D) and lE15 [#/kg] (W) mark the fraction of non-volatile (=soot) particles (see Petzold et al., this issue) with just a minor contribution to Ns and N14, respectively. Starting with the drv exhaust plume case and high sulfur fuel burned (HD) we report as much as Ns = 1.4E17 [#/kg] (almost) volatile aerosols while N,d-values increase from 4E15 to 9E15 in between about Is-10s plume age. At the same time low sulfur fuel yields at least ten times lower Nrvalues, increasing by a factor of four (5E15 to 2E16 [#/kg]) while Nt4 remains constant around 2.4E15. Constant Nr, and doubling of N14 for the HD case implies mean particle diameters DM > 5 nm already 1 second past exit. On the other hand (the LD case) unchanged N,b-values and strongly increasing Ns are consistent with a smaller particle mode growing from below 5 nm into the CPC detection range during the Is-10s period. Suggesting Du = 10 nm for the HD-case the volume fraction of new generated particulate matter (estimated H$SOJ&O solution droplets, 1: 1 volume ratio) reaches about 150 ppmv which corresponds to about 2.5% conversion of fuel sulfur to particulate H$!i04” For the LD-case (Ns=2E16 and estimated DM = 5 nm) the conversion rate is most likely higher. However, since considerable amounts of condensed matter are likely to exist below the CPC-detection range and the potential involvement of other condensing species in new particle production, certainly masked in the HD case, cannot be excluded, a further understanding of the LD-case requires a detailed physiochemistry model study. S561
5362
Abstracts
of the 5th International
Aerosol Conference
1998
Measurements under contrail forming Contrail Dry Exhaust conditions (W, right figure) generally yielded a factor of 2 less particle concentrations: Ni4 = 1.2E15 (LW), N14 = 5E15 (HW); Ns = 5E15 (LW) as well as N5 = 7E16 (HW) both with a decreasing tendency between 2 and 20 seconds with consistent plume and age = calculations of coagulation scavenging onto contrail ice crystals (lpm in -2 diameter). These crystals must also contain significant fractions of the Z %.I primary emitted soot aerosol, since even the “soot level“ is clearly lower in the WZ compared to the D-case and the aerosol sampling system is insensitive to supermicron particles like ice crystals. Thus, the discrepancy in the soot fractions yields evidence for the involvement of non-volatile aerosol as condensation nuclei in the contrail forming process. this work shows that In summary, 1 10 10 1 sulfur content fuel increasing Plume Age [s] significantly increases the emission index of ultrafine volatile aerosols of jet that illustrates also aircraft. It coagulation scavenging of fine mode Figure 1: (Mostly) volatile particle abundance vs plume particles takes place onto contrail ice age measured in the dry exhaust plume (0) and under crystals and that - consequently - an contrail forming conditions (W). Shown are Ns (open evaporating contrail will release an symbols) and N14 (filled symbols) for the L- (triangles) “cloud-processed” aerosol. In already and H-cases (circles). Lines indicate sulfur-induced contrast to dry aircraft exhaust products particle growth (0. trends fitted to data) and particle this aerosol is characterized by lower scavenging onto contrail ice (W, calculated trends). CN-concentrations (condensation nuclei) but - most likely - a larger amount of Aitken-mode soot particles containing significant quantities of highly hygroscopic, liquid H2S0JI-120-coating. This property makes them potential candidates for CCN (cloud condensation nuclei) rather than unprocessed soot emissions. ACKNOWLEDGEMENTS We thank the pilots and the stuff of DLR Flight Department for essential contributions experiment; further U. Schumann and Reinhold Busen for valuable discussions on this work.
to a successful
REFERENCES 1995: Particle detection efficiency curve of the TSI-3010 CPC as a function of the temperature difference between saturator and condenser, Aeros. Sci. Technol. 23: 257-261 Schriider, F. and J. StrSm, 1997: Aircraft measurements of sub micrometer aerosol particles (>7nm) in the midlatitude free troposphere and tropopause region, Atmos. Research, 44.333-356 Schriider, F., B. Kiircher, A. Petzold, R. Baumann, R. Busen, C. Hiill, and U. Schumann, 1998: Ultratine aerosol particles in aircraft plumes: In-situ observations, submitted to GRL Mertes, S., F. Schriider,
and A.Wiedensohler,