Comprehensive study of initial diameter effects and other observations on convection-free droplet combustion in the standard atmosphere for n-heptane, n-octane, and n-decane

Liu, Yucheng; Xu, Yuhao; Hicks, M.; Avedisian, C. Thomas

doi:10.1016/j.combustflame.2016.05.013

Cited by 58 publications

(26 citation statements)

References 54 publications

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“…The second kind of images are those captured with camera 2 (Figure a), which aimed to record the individual envelope flames that surrounded the droplets. As was discussed in a previous work, the black body radiation emitted from soot particles is considerably more intense than the chemiluminescence emission from electronically excited radicals such as OH* or CH*, which are the most broadly accepted light-emitting species when it comes to establishing the flame position. − Given the high sooting tendency of the fuels studied here, soot emission heavily predominated in this kind of images, and therefore, it would be more correct to speak of soot clouds rather than flame pictures. Soot particles are formed on the inner side of the shell flame, and therefore, the light emission from excited radicals produced in chemical reactions would be located slightly further away from the droplet.…”

Section: Resultsmentioning

confidence: 61%

Properties and Combustion Characteristics of Bio-Oils from Catalytic Co-Pyrolysis of Grape Seeds, Polystyrene, and Waste Tires

et al. 2020

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This work aims to study the bio-oils obtained from the catalytic co-pyrolysis of waste polymers and a residual biomass (grape seeds, GS). For that purpose, the organic liquid fractions produced in an auger reactor were thoroughly characterized in two steps, obtaining in the first place their main physicochemical properties as well as their chemical compositions, and second, their droplet combustion behaviors. Both the polymer type (waste tires or polystyrene, WT and PS, respectively) and the nature of the low-cost, calcium-based catalyst used (Carmeuse limestone, calcined dolomite, or an inert material such as sand) were studied. A significant improvement in the physicochemical properties of the bio-oils was obtained when using a catalyst, with lower viscosity, density, and oxygen content. These beneficial effects were more marked for the bio-oil produced with the Carmeuse catalyst, presumably due to the higher prevalence of aromatization and hydro-deoxygenation reactions. When changing the polymer source from WT to PS, a considerable increase in the aromatic content and a viscosity reduction were noted. The droplet combustion tests revealed the consistent occurrence of microexplosions for all of the studied bio-liquids, these bursting events being more violent for the GS−PS oil. Regarding the evaporation behavior, this liquid also yielded significantly higher burning rates during the initial heatup phase, in agreement with its richer composition in volatile compounds such as styrene. These results point to this fuel as the one with the best global combustion behavior from all of the explored bio-oils. The GS−WT liquids showed much closer features among them, although with noticeable differences depending on the catalyst used. A more volatile behavior was observed for GS−WT Carmeuse, followed by GS−WT dolomite and GS−WT sand, strengthening thus the previously reported improvements in physicochemical properties. Finally, the propensity to form soot of these bio-oils was characterized through a soot probe, which revealed a higher soot yield for the bio-liquids produced with the Carmeuse catalyst.

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Section: Resultsmentioning

confidence: 61%

Properties and Combustion Characteristics of Bio-Oils from Catalytic Co-Pyrolysis of Grape Seeds, Polystyrene, and Waste Tires

et al. 2020

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“…The data used are from the Flame Extinguishment Experiment (FLEX), conducted on board the International Space Station by NASA [13][14][15][16]. The experiments used n-heptane, n-decane and n-octane droplets of initial size ranging from 0.85mm to 4.36mm and all the data provided are from free-floating B ( )…”

Section: Data Assimilation Implementation With Experimental Observationsmentioning

confidence: 99%

Data driven forecast of droplet combustion

Torero

Jahn

2021

Proceedings of the Combustion Institute

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The characteristics of a diffusion flame resulting from the gasification of a condensed fuel are predicted from the synthesis of simple models and data. Combustion of a droplet in microgravity is used as a canonical configuration to illustrate the methodology. The simplicity of the spherical configuration and the detail of the measurements make the available experimental data ideal for this study. The approach followed combines the classical analytical solution first proposed by Spalding to describe the condensed phase gasification with a numerical method that describes the gas phase.Available data on flame geometry and regression rates are used to initialize the model and produce adequate predictions of the time evolution of all relevant variables. The method was shown to make proper predictions under numerous configurations and with very small computational cost.

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“…Recently phenomena of droplet cool flame documented through the FLEX experiments [9] have motivated investigation and modelling efforts in such diffusio-chemically coupled problem. Liu et al [10] and Xu et al [11] analysed the droplet burning experiments in FLEX. The cool flame appears after radiative extinction of hot flames.…”

Section: Introductionmentioning

confidence: 99%

The effect of droplet size on boundary migration of burning modes for autoignition of n-heptane droplets

Zhang

Zhou

Liu

2021

ICLASS

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The purpose of this study is to understand the effect of various diameter or ambient parameters on the autoignition and quasi-steady burning of n-heptane droplets. Spherically symmetric 1-D numerical simulations were conducted with various initial droplet diameter (50 μm~2 mm), ambient temperature (500-1000 K) and pressure (1~20 bar) to facilitate identification of ignition dynamics and intrinsic steady burning modes, including steady droplet cool flame, cool-to-hot transition and hot flame after single ignition, etc. Provided that different initial temperatures and pressures lead to a variety of ignition states, initial droplet diameters present further constraint to ignition behaviours through physical droplet life time. Such constraint sometimes can turn a two-stage ignition (longer life time) into a cool flame (shorter life time). Species with strong correlation with cool flame (KET (NC7KET24)) and hot flame (OH) were used as identifiers for the dynamics of corresponding processes. FSR (Flame standoff ratio) for both cool and hot flame was found to be stabilized at FSRcool ≈1.3, and FSRhot ≈3.8, respectively. The effect of droplet diameter is obvious when the droplet life time determines the termination of a heat release history. Such effect becomes less important for the mode boundaries primarily governed by fuel oxidation kinetics, i.e. between two-stage and single hot ignition (or between no ignition and single hot ignition).

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Comprehensive study of initial diameter effects and other observations on convection-free droplet combustion in the standard atmosphere for n-heptane, n-octane, and n-decane

Cited by 58 publications

References 54 publications

Properties and Combustion Characteristics of Bio-Oils from Catalytic Co-Pyrolysis of Grape Seeds, Polystyrene, and Waste Tires

Properties and Combustion Characteristics of Bio-Oils from Catalytic Co-Pyrolysis of Grape Seeds, Polystyrene, and Waste Tires

Data driven forecast of droplet combustion

The effect of droplet size on boundary migration of burning modes for autoignition of n-heptane droplets

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