Numerical study of fuel temperature influence on single gas jet combustion in highly preheated and oxygen deficient air

Yang, Weihong; Blasiak, Włodzimierz

doi:10.1016/j.energy.2004.05.011

Cited by 90 publications

(70 citation statements)

References 5 publications

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“…A more accurate and less subjective method was proposed to describe a flame based on the species concentrations; this type of flame was named as "chemical flame" [29]. The chemical flame of solid fuels and the flame parameters are schematized in Figure 3.…”

Section: Flame Parametersmentioning

confidence: 99%

“…All of the flame parameters based on the chemical flame data, including the flame lift-off distance, flame length and maximum flame diameter, are distinguished from the luminous flame parameters based on visual observations. In this work, the chemical flame was employed to describe the shape and position of a flame inside the furnace based on the following equation [29]:…”

Section: Flame Parametersmentioning

confidence: 99%

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Flame characteristics of pulverized torrefied-biomass combusted with high-temperature air

Biagini

Yang

et al. 2013

Combustion and Flame

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This version is available at https://strathprints.strath.ac.uk/53528/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Abstract:In this work, the flame characteristics of torrefied biomass were studied numerically under hightemperature air conditions to further understand the combustion performances of biomass.Three torrefied biomasses were prepared with different torrefaction degrees after by releasing 10%, 20%, and 30% of volatile matter on a dry basis and characterized in laboratory with standard and high heating rate analyses. The effects of the torrefaction degree, oxygen concentration, transport air velocity, and particle size on the flame position, flame shape, and peak temperature are discussed based on both direct measurements in a laboratory-scale furnace and CFD simulations. The results primarily showed that the enhanced drag force on the biomass particles caused a late release of volatile matter and resulted in a delay in the ignition of the fuelair mixture, and the maximum flame diameter was mainly affected by the volatile content of the biomass materials. Furthermore, oxidizers with lower oxygen concentrations always resulted in a larger flame volume, a lower peak flame temperature and a lower NO emission. Finally, a longer flame was found when the transport air velocity was lower, and the flame front gradually moved to the furnace exit as the particle size increased. The results could be used as references for designing a new biomass combustion chamber or switching an existing coal-fired boiler to the combustion of biomass.

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Section: Flame Parametersmentioning

confidence: 99%

Section: Flame Parametersmentioning

confidence: 99%

Flame characteristics of pulverized torrefied-biomass combusted with high-temperature air

Biagini

Yang

et al. 2013

Combustion and Flame

Self Cite

View full text Add to dashboard Cite

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“…These shortcomings are attributable to the over-prediction of the turbulent viscosity, and the use of an inappropriate turbulence length scale in the transport equations for k and [15]. This has led to the development of non-linear variants of the EVM (NEVM).…”

Section: Turbulent Flow Modellingmentioning

confidence: 99%

“…Consequently, most of the previous numerical studies of flares have employed RANS-based approaches to predicting the turbulent flow field. Previous attempts to predict the flame temperature in the far-field and planar flame zone in the wake of the release pipe using the standard k-turbulence model have been less than successful for both methane [14] and propane flares [15], and this was attributed to the inadequacy of the eddy-viscosity turbulence models (EVM) employed in these studies. To overcome these limitations within the RANS modelling framework, the authors suggest the use of second-moment turbulence closures, namely Reynolds stress models (RSM).…”

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confidence: 98%

CFD predictions of wake-stabilised jet flames in a cross-flow

Lawal¹,

Fairweather²,

Gogolek³

et al. 2013

Energy

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This study describes an investigation into predicting the major flow properties in wake-stabilised jet flames in a cross flow of air using first-and second-order turbulence models, applied within a Reynolds-averaged Navier-Stokes (RANS) modelling framework. Standard and re-normalisation group (RNG) versions of the k-turbulence model were employed at the first-order level and the results compared with a secondmoment closure, or Reynolds stress model (RSM). The combustion process was modelled using the laminar flamelet approach together with a thermal radiation model using the discrete ordinate method. The ability of the various turbulence models to reproduce experimentally established flame appearance, profiles of velocity and turbulence intensity, as well as the combustion efficiency of such flames is reported. The results show that all the turbulence models predict similar velocity profiles over the majority of the flow domain considered, except in the wake region, where the predictions of the RSM and RNG k-models are in closer agreement with experimental data. In contrast, the standard k-model over-predicts the peak turbulence intensity. Also, it is found that the RSM provides superior predictions of the planar recirculation and flame zones attached to the release pipe in the wake region. 1.IntroductionA large quantity of oil field associated gas, and waste hydrocarbons from the process industry, is flared globally each year. With the predicted increase in oil production in the next decades, a significant increase in flaring is expected [1,2]. However, flare operations can result in the formation of pollutants such as unburned hydrocarbons, CO, NO x and noise and the effect of a cross-flow of wind can be significant. In order to minimise these effects, a detailed understanding of the flow features and structures of these non-premixed jet flames in a cross-flow (JFICF) is necessary. Depending on the value of the jetto-cross-flow momentum flux ratio, R= j u j 2 / cf u cf 2 , where j , cf and u j , u cf are the density and velocity of the fuel jet and the cross-flow, respectively, the flow features that arise in the JFICF have an important influence on the flame's combustion characteristics.For flares operating at low values of R, typically R ≤ 1.0, the flame is either seated on the flare stack or stabilised in its wake [3]. The latter case is also known as a wake-stabilised flare which belongs to a flow regime where the flame is severely bent-over by the cross-flow and has high turbulence intensities in the near-field [4]. This category of flare is commonly found in offshore crude oil production facilities.The three main flow features in the wake-stabilised flare include: a counter-rotating vortex pair (CVP)[5], coherent structures around the upper surface of the jet [3] and the planar recirculation zone in the wake of the stack [6]. The latter zone is part of the low-pressure region where a secondary flame is attached to the release pipe, as shown in Fig. 1, and the vortex dynamics and mixing in this ...

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“…The flame volume can be explained with support of oxidation mixture ratio [24] in form of Equation (18) With respect to constant O2 concentration in the co-flow, the change in the flame volume caused by a high temperature co-flow is not sufficient to cover the local enthalpy increase in the system and thus the peak temperature is enhanced. For the co-flow with 6%vol and 9%vol O2 concentrations, when the co-flow temperature increases, the flame volume is enlarged much more than in other O2 concentration conditions.…”

Section: Influence Of O2 Concentration In the Co-flowmentioning

confidence: 99%

Numerical investigation of spray combustion towards HiTAC conditions

Zhu¹

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Numerical study of fuel temperature influence on single gas jet combustion in highly preheated and oxygen deficient air

Cited by 90 publications

References 5 publications

Flame characteristics of pulverized torrefied-biomass combusted with high-temperature air

Flame characteristics of pulverized torrefied-biomass combusted with high-temperature air

CFD predictions of wake-stabilised jet flames in a cross-flow

Numerical investigation of spray combustion towards HiTAC conditions

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