Scattering and absorptive characteristics of a cenosphere

Huang, Yong; Zhao, Rong; Jiang, Junwei; Zhu, Keyong

doi:10.1016/j.ijthermalsci.2012.01.019

Cited by 6 publications

(2 citation statements)

References 14 publications

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“…Cenospheres are core‐shell BC particles with air cores and have been observed in HFO PM (e.g., Chen et al, ). They may be modeled accurately with core‐shell Mie theory (Huang et al, ), which we have done in Figure S3. The cenospheres were modeled with a ratio of inner to outer diameters of 0.8(the abscissa of Figure S3 is the outer diameter).…”

Section: Resultsmentioning

confidence: 99%

Brown and Black Carbon Emitted by a Marine Engine Operated on Heavy Fuel Oil and Distillate Fuels: Optical Properties, Size Distributions, and Emission Factors

et al. 2018

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We characterized the chemical composition and optical properties of particulate matter (PM) emitted by a marine diesel engine operated on heavy fuel oil (HFO), marine gas oil (MGO), and diesel fuel (DF). For all three fuels, ∼80% of submicron PM was organic (and sulfate, for HFO at higher engine loads). Emission factors varied only slightly with engine load. Refractory black carbon (rBC) particles were not thickly coated for any fuel; rBC was therefore externally mixed from organic and sulfate PM. For MGO and DF PM, rBC particles were lognormally distributed in size (mode at d rBC ≈120 nm). For HFO, much larger rBC particles were present. Combining the rBC mass concentrations with in situ absorption measurements yielded an rBC mass absorption coefficient MAC BC,780 nm of 7.8 ± 1.8 m 2 /g at 780 nm for all three fuels. Using positive deviations of the absorption Ångström exponent (AAE) from unity to define brown carbon (brC), we found that brC absorption was negligible for MGO or DF PM (AAE(370,880 nm) ≈ 1.0 ± 0.1) but typically 50% of total 370-nm absorption for HFO PM. Even at 590 nm, ∼20 of the total absorption was due to brC. Using absorption at 880 nm as a reference for BC absorption and normalizing to organic PM mass, we obtained a MAC OM,370 nm of 0.4 m 2 /g at typical operating conditions. Furthermore, we calculated an imaginary refractive index of (0.045 ± 0.025)( ∕370 nm) −3 for HFO PM at 370 nm> > 660 nm, more than twofold greater than previous recommendations. Climate models should account for this substantial brC absorption in HFO PM. Plain Language SummaryWe characterized the fundamental properties of marine engine exhaust that are relevant to its aerosol-radiation interactions in climate models. In particular, we focussed on "brown carbon" light absorption (i.e., absorption in excess of that expected for the black carbon in canonical soot). We found that brown carbon can increase the direct radiative forcing of heavy-fuel-oil ship exhaust by 18% over snow.

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Section: Resultsmentioning

confidence: 99%

Brown and Black Carbon Emitted by a Marine Engine Operated on Heavy Fuel Oil and Distillate Fuels: Optical Properties, Size Distributions, and Emission Factors

et al. 2018

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“…Mie theory provides an accurate representation of char cenospheres. 71 The shell thickness was set by assigning an inner diameter that was 60% of the outer diameter (0.6 and 1.0 μm, respectively), as constrained by the data of Zhu et al, 31 but the results were not sensitive to this choice. The AAEs in Fig.…”

Section: Lac Model Calculationsmentioning

confidence: 99%

Infrared-absorbing carbonaceous tar can dominate light absorption by marine-engine exhaust

et al. 2019

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Ship engines in the open ocean and Arctic typically combust heavy fuel oil (HFO), resulting in light-absorbing particulate matter (PM) emissions that have been attributed to black carbon (BC) and conventional, soluble brown carbon (brC). We show here that neither BC nor soluble brC is the major light-absorbing carbon (LAC) species in HFO-combustion PM. Instead, "tar brC" dominates. This tar brC, previously identified only in open-biomass-burning emissions, shares key defining properties with BC: it is insoluble, refractory, and substantially absorbs visible and near-infrared light. Relative to BC, tar brC has a higher Angstrom absorption exponent (AAE) (2.5-6, depending on the considered wavelengths), a moderately-high mass absorption efficiency (up to 50% of that of BC), and a lower ratio of sp 2-to sp 3-bonded carbon. Based on our results, we present a refined classification of atmospheric LAC into two sub-types of BC and two sub-types of brC. We apply this refined classification to demonstrate that common analytical techniques for BC must be interpreted with care when applied to tar-containing aerosols. The global significance of our results is indicated by field observations which suggest that tar brC already contributes to Arctic snow darkening, an effect which may be magnified over upcoming decades as Arctic shipping continues to intensify.

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Analytical solutions and numerical simulations of radiative property in the two-layer concentrically spherical large particle

Zhu

Huang

2019

International Journal of Heat and Mass Transfer

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Scattering and absorptive characteristics of a cenosphere

Cited by 6 publications

References 14 publications

Brown and Black Carbon Emitted by a Marine Engine Operated on Heavy Fuel Oil and Distillate Fuels: Optical Properties, Size Distributions, and Emission Factors

Brown and Black Carbon Emitted by a Marine Engine Operated on Heavy Fuel Oil and Distillate Fuels: Optical Properties, Size Distributions, and Emission Factors

Infrared-absorbing carbonaceous tar can dominate light absorption by marine-engine exhaust

Analytical solutions and numerical simulations of radiative property in the two-layer concentrically spherical large particle

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