Raman Spectroscopy of Soot Sampled in High-Pressure Diffusion Flames

Commodo, Mario; Joo, Peter H.; Falco, Gianluigi De; D’Anna, Andrea; Gülder, Ömer L.

doi:10.1021/acs.energyfuels.7b01674

Cited by 32 publications

(15 citation statements)

References 48 publications

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“…This material, before solvent extraction, in the following is referred to as whole particulate. More information on the Raman technique can be found in [18].…”

Section: Carbon Experimental Characterizationmentioning

confidence: 99%

On the Formation and Accumulation of Solid Carbon Particles in High-Enthalpy Flows Mimicking Re-Entry in the Titan Atmosphere

Espósito

Lappa

Zuppardi

et al. 2020

Fluids

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The problem relating to the formation of solid particles enabled by hypersonic re-entry in methane-containing atmospheres (such as that of Titan) has been tackled in the framework of a combined experimental–numerical approach implemented via a three-level analysis hierarchy. First experimental tests have been conducted using a wind tunnel driven by an industrial arc-heated facility operating with nitrogen as working gas (the SPES, i.e., the Small Planetary Entry Simulator). The formation of solid phases as a result of the complex chemical reactions established in such conditions has been detected and quantitatively measured with high accuracy. In a second stage of the study, insights into the related formation process have been obtained by using multispecies models relying on the NASA CEA code and the Direct Simulation Monte Carlo (DSMC) method. Through this approach the range of flow enthalpies in which carbonaceous deposits can be formed has been identified, obtaining good agreement with the experimental findings. Finally, the deposited substance has been analyzed by means of a set of complementary diagnostic techniques, i.e., SEM, spectroscopy (Raman, FTIR, UV–visible absorption and fluorescence), GC–MS and TGA. It has been found that carbon produced by the interaction of the simulated Titan atmosphere with a solid probe at very high temperatures can be separated into two chemically different fractions, which also include “tholins”.

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“…This material, before solvent extraction, in the following is referred to as whole particulate. More information on the Raman technique can be found in [18].…”

Section: Carbon Experimental Characterizationmentioning

confidence: 99%

On the Formation and Accumulation of Solid Carbon Particles in High-Enthalpy Flows Mimicking Re-Entry in the Titan Atmosphere

Espósito

Lappa

Zuppardi

et al. 2020

Fluids

Self Cite

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“…Raman spectroscopy is a valuable tool for probing carbon structure and elucidating soot properties such as absorption cross-section [23], optical band gap [24], and crystallite size [25]. A wealth of knowledge has been obtained from analysis of Raman spectra for soot formed in premixed flames [26][27][28][29][30][31][32], diffusion flames [25,26,[33][34][35][36], and engines [37,38]. Although the range of flame conditions is large, the characteristics of the Raman spectra fall within a narrow range.…”

Section: Introductionmentioning

confidence: 99%

Evolution in size and structural order for incipient soot formed at flame temperatures greater than 2100 K

Dasappa

Camacho

2021

Fuel

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Evolution in size and structural order for incipient soot formed at flame temperatures greater than 2100 K Shruthi Dasappa a,b and Joaquin Camacho *a Soot formed in flames hotter than conventional combustion applications is expected to undergo unique formation processes and develop a carbon structure distinct from typical soot. A complementary experimental and modeling approach is reported here to assess flame temperature and equivalence ratio effects for soot formed in the higher-temperature regime (1950 K < Tf < 2250 K). Computations using three separate combustion chemistry models show that predictions of polycyclic aromatic hydrocarbon (PAH) concentration profiles for the highertemperature flames are more sensitive to the choice in mechanism rather than specific flame conditions. As for material properties, the Raman signatures transition from a typical soot spectrum to features observed in disordered sp 2 carbon materials. The defect distance extracted from the Raman bands nearly doubles from values typically reported for soot as the flame temperature exceeds 2200 K. Higher concentrations of gas-phase precursors may facilitate development of an ordered carbon structure as indicated by the relatively high defect distance observed for the highest equivalence ratio series. Particle size distributions measured by mobility sizing show size and yield of soot decreases with increasing flame temperature and the bimodal distribution falls within the ultra-fine range for all flame conditions. This is especially promising if the significant transformation in carbon structure inferred from the evolution in Raman spectra enables development of functional high-surface area sp 2 carbon materials. Namely, the current observations indicate that the flame-formed carbon structure evolves towards high-defect sp 2 carbon with size and carbon structure that can be tuned to some extent.

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“…Moreover, due to high-pressure industrial applications of combustion, studying higher pressure flames is at the center of attention for academics and industry professionals. There is a sufficient number of experimental studies on high pressure co-flow diffusion flames for different fuels including ethylene and ethane [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] with only a few numerical studies [26][27][28][29][30]. Although experimental studies are necessary for validation and also to assess soot formation and oxidation behaviour, numerical studies are more suitable for large parametric studies due to lower cost and ability to investigate a wider range of parameters in a smaller timeframe.…”

Section: Introduction On Surface Growthmentioning

confidence: 99%

Impact of pressure-based HACA rates on soot formation in varying-pressure coflow laminar diffusion flames

Mansouri

Zimmer

Dworkin

et al. 2020

Combustion and Flame

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There are several processes to occur in soot formation and destruction for which some in the growth regime require a better understanding. In this work, a consistent surface reactivity model, developed in recent years, has been implemented across various sooting laminar flames at varying pressures. The surface reactivity function proposed by Khosousi and Dworkin [1] is employed in the present study. It is based on the temperature history of soot particles. As the functionally dependent model has been derived and validated for atmospheric pressure flames, there are discrepancies between simulation and experiment that can be observed as pressures vary. One reason for these discrepancies could be explained by the fact that chemical reaction rates for the soot growth mechanism at atmospheric combustion do not adequately characterize the kinetics at higher pressures. Based on a recently published study [2], the elementary reaction rates that compose the Hydogen-Addition-Carbon-Abstraction soot surface growth mechanism depend on pressure and an empirical pressure scaling factor to account for this pressure dependence has been introduced. It has been determined that after applying the new empirical pressure scaling factor for the soot growth mechanism, the performance of the functionally dependent surface reactivity model improves in the wing regions of the flame for pure-ethylene flames; however, there is minimal change on the wings for the nitrogen-diluted flames. Additionally, the quantity for soot concentration along the centerline of all flames is nearly independent of the surface reactivity model chosen and needs further investigation. For the flames investigated, it is concluded that pressure dependent

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Raman Spectroscopy of Soot Sampled in High-Pressure Diffusion Flames

Cited by 32 publications

References 48 publications

On the Formation and Accumulation of Solid Carbon Particles in High-Enthalpy Flows Mimicking Re-Entry in the Titan Atmosphere

On the Formation and Accumulation of Solid Carbon Particles in High-Enthalpy Flows Mimicking Re-Entry in the Titan Atmosphere

Evolution in size and structural order for incipient soot formed at flame temperatures greater than 2100 K

Impact of pressure-based HACA rates on soot formation in varying-pressure coflow laminar diffusion flames

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