Experimental investigation of nitrogen addition effect on combustion characteristics of buoyant turbulent diffusion flame

Bi, Yubo; Chen, Jian; Chen, Xiao; Lu, Shouxiang; Li, Changhai

doi:10.1016/j.fuel.2018.12.001

Cited by 21 publications

(6 citation statements)

References 45 publications

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“…The characteristic formation time τ s is related to S 20,37 :

τ_{s} \propto {(L_{f})}_{sp} \propto S^{- 1 / 2} .

Combining Equations (14) and (15), the total soot volume fraction f v,total can be described as:

f_{normalv, total} \propto {(S + 1)}^{- 1} {\dot{Q}}^{1 / 5} normalΔ H_{c} S^{1 / 2} .

The calculated total soot volume fraction by Equation (6) is related to the radially integrated soot volume fraction at different heights and shows a similar trend with fuel concentration. The results are presented together with the fitting line as shown in Figure 7, indicating a good agreement between experimental results and theoretical analysis with correlation coefficient being 0.96:

f_{normalv, total} goodbreak= 0.019 {(S + 1)}^{- 1} {\dot{Q}}^{1 / 5} normalΔ H_{c} S^{1 / 2} goodbreak- 0.046 .

…”

Section: Resultsmentioning

confidence: 85%

“…The video with a length of 30 s of the steady burning stage of each experiment was used for calculation. The results of mean flame length and flame diameter in Table 1 demonstrated that the nitrogen addition has almost no effect on mean flame height and diameter for a same propane flow rate 20 . The flame length of buoyancy‐driven flame is mainly related to heat release rate and burner diameter.…”

Section: Methodsmentioning

confidence: 96%

“…The mean flame length for turbulent fire is defined as the length where the intermittency is 0.5. The mean flame diameter is defined as the maximum width for the flame sheet with the intermittency of 0.5 and the height of 0.1 m above the burner exit considering the effect of burner exit on the calculating process 20 . The video with a length of 30 s of the steady burning stage of each experiment was used for calculation.…”

Section: Methodsmentioning

confidence: 99%

“…The mean flame diameter is defined as the maximum width for the flame sheet with the intermittency of 0.5 and the height of 0.1 m above the burner exit considering the effect of burner exit on the calculating process. 20 The video with a length of 30 s of the steady burning stage of each experiment was used for calculation. The results of mean flame length and flame diameter in Table 1 demonstrated that the nitrogen addition has almost no effect on mean flame height and diameter for a same propane flow rate.…”

Section: Burner and Firementioning

confidence: 99%

“…The results of mean flame length and flame diameter in Table 1 demonstrated that the nitrogen addition has almost no effect on mean flame height and diameter for a same propane flow rate. 20 The flame length of buoyancy-driven flame is mainly related to heat release rate and burner diameter. Besides, the flame volume has been found to be proportional to heat release rate.…”

Section: Burner and Firementioning

confidence: 99%

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Statistical study on soot volume fractions of buoyant turbulent diffusion fires

Gao

et al. 2022

Fire and Materials

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The statistical soot properties of buoyant turbulent diffusion propane fire were experimentally and theoretically studied with different fuel sooting tendencies by nitrogen addition. Results show that nitrogen addition decreases the instantaneous soot volume fraction and increases soot intermittency. The combination of these two factors together leads to a decrease in mean soot volume fraction when nitrogen is added. Both radially integrated and the total soot volume fraction decrease with nitrogen addition. The radially integrated soot volume fraction is found to be a function of fuel concentration. A dimensionless correlation is proposed to predict the total soot volume fraction based on theoretical analysis and in good agreement with the experimental data. The results could provide guidance for predicting soot yield for buoyant turbulent fires.

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“…The characteristic formation time τ s is related to S 20,37 :

τ_{s} \propto {(L_{f})}_{sp} \propto S^{- 1 / 2} .

Combining Equations (14) and (15), the total soot volume fraction f v,total can be described as:

f_{normalv, total} \propto {(S + 1)}^{- 1} {\dot{Q}}^{1 / 5} normalΔ H_{c} S^{1 / 2} .

f_{normalv, total} goodbreak= 0.019 {(S + 1)}^{- 1} {\dot{Q}}^{1 / 5} normalΔ H_{c} S^{1 / 2} goodbreak- 0.046 .

…”

Section: Resultsmentioning

confidence: 85%

Section: Methodsmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Section: Burner and Firementioning

confidence: 99%

Section: Burner and Firementioning

confidence: 99%

See 3 more Smart Citations

Statistical study on soot volume fractions of buoyant turbulent diffusion fires

Gao

et al. 2022

Fire and Materials

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Soot sheet characteristics of turbulent diffusion fire using equivalent ellipse method

et al. 2023

Fire and Materials

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This paper investigates the soot sheet characteristics of buoyant turbulent fires using laser‐induced incandescence technique. Experiments are carried out for four fires using propane and nitrogen hybrid gases as fuel with propane fractions of 1.0–0.4. An equivalent ellipse method in previous literature was employed to evaluate soot sheet characteristics. The results show that soot sheet mainly exists in two kinds of morphology: one is small piece and the other is narrow and long piece. Both the probability density functions of the length and width of the equivalent ellipse and soot volume fraction of soot sheet are strongly dependent on height. In addition, the effect of propane fraction on the probability density functions is always opposite in the lower and middle part of the fires, while no obvious effect can be found in the upper part of the fires. Soot sheet number is found to increase with height except when propane fraction is 0.4. The total soot sheet number increases linearly with height within the scope of this paper.

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