初始温度对掺氢天然气可燃下限的影响

doi:10.12068/j.issn.1005-3026.2024.11.015

摘要/Abstract

摘要：

实验研究不同初始温度下掺氢天然气可燃下限变化规律，分析初始温度对掺氢天然气近极限预混燃烧影响机制，并利用Le Chatelier及Kondo公式对掺氢天然气可燃下限进行理论计算.研究发现，掺氢天然气可燃下限随掺氢比增加逐渐下降，高温下这种变化趋势更显著；掺氢天然气可燃下限随初始温度升高近线性下降，高温下H自由基摩尔分数的升高显著增强H+O₂=O+OH对近极限预混燃烧过程的主导促进作用. Le Chatelier公式能较准确预测掺氢天然气可燃下限随掺氢比变化规律.当掺氢比较低时，Kondo公式能较准确预测掺氢天然气可燃下限随初始温度近线性变化趋势，但当掺氢比和初始温度较高时，掺氢天然气近极限预混燃烧过程主导反应及重要自由基摩尔分数显著变化，使其预测结果准确性显著降低.

关键词: 可燃下限, 初始温度, 掺氢比, 重要自由基, Le Chatelier公式

Abstract:

The lower flammability limits of H₂/CH₄ mixtures over a wide range of H₂ fractions are systematic experimentally studied at various initial temperatures. The effect of initial temperatures on the near?limit flames of H₂/CH₄ mixtures is insightfully discussed. In addition， the estimations of the lower flammability limits of H₂/CH₄ mixtures is also calculated using Le Chatelier rule and Kondo’s correlation. The results show that the lower flammability limits of H₂/CH₄ mixtures decrease with the growth of H₂ fractions under all measured initial temperatures. The greater declines of lower flammability limits are presented at higher initial temperatures. Moreover， the lower flammability limits of H₂/CH₄ mixtures almost linearly decrease with the increase of initial temperatures. Under the higher initial temperatures， the dominant promotion of H+O₂=O+OH on the near-limit flames of H₂/CH₄ mixtures is enhanced by the significant increase of H radicals. The comparison between the experimental data and calculation results shows that Le Chatelier rule presents satisfactory applications on estimating lower flammability limits of H₂/CH₄ mixtures based on the accurate measurements. Kondo’s correlation provides the greater accurate predictions on the linear temperature dependence of the lower flammability limits of mixtures with lower H₂ fractions. However， the considerable distinctions between experimental data and calculation results using Kondo’s correlation at higher H₂ fractions under elevated initial temperatures are attributed to the significant variation of the sensitivity of dominant reactions and the mole fractions of vital radicals.

Key words: lower flammable limit, initial temperature, hydrogen fraction, vital radical, Le Chatelier rule

中图分类号:

X 932

尚融雪, 孙浩英, 庄紫喧, 李刚. 初始温度对掺氢天然气可燃下限的影响[J]. 东北大学学报（自然科学版）, 2024, 45(11): 1638-1644.

Rong-xue SHANG, Hao-ying SUN, Zi-xuan ZHUANG, Gang LI. Effect of Initial Temperatures on Lower Flammability Limits of H₂/CH₄ Mixtures[J]. Journal of Northeastern University(Natural Science), 2024, 45(11): 1638-1644.

图/表 10

图1 掺氢天然气可燃下限随掺氢比的变化规律

Fig.1 Lower flammability limits of H2/CH4 mixtures with different H2 fractions

图2 不同掺氢比条件下的掺氢天然气质量燃烧速率敏感性分析

Fig.2 Sensitivity analysis of mass combustion rate of H2/CH4 mixtures with different H2 fractions

图3 不同掺氢比条件下掺氢天然气预混火焰H自由基的摩尔分数

Fig.3 Molar fraction of H radical of H2/CH4 mixtures with different H2 fractions

图4 不同掺氢比下掺氢天然气可燃下限Le Chatelier公式理论计算值

Fig.4 Calculation of lower flammability limits of H2/CH4 mixtures with different H2 fractions using Le Chatelier rule

图5 掺氢天然气可燃下限随初始温度的变化规律

Fig.5 Lower flammability limits of H2/CH4 mixtures under different initial temperatures

图6 不同初始温度下的掺氢天然气质量燃烧速率敏感性分析

Fig.6 Sensitivity analysis of mass combustion rate of H2/CH4 mixtures under different initial temperatures

图7 不同初始温度下的掺氢天然气预混火焰H自由基摩尔分数

Fig.7 Molar fraction of H radical of H2/CH4 mixtures under different initial temperatures

图8 掺氢天然气可燃下限随初始温度线性拟合结果

Fig.8 Dependence of initial temperatures on the experimental lower flammability limits of H2/CH4 mixtures using linear regression

表1 线性拟合关系式及拟合优度R2 (regression)

Table 1 Fitting correlations and R2 of linear

掺氢比	拟合关系式	拟合优度R²
0	y=-0.004x+6.362	0.942
0.25	y=-0.007x+7.225	0.971
0.5	y=-0.012x+8.635	0.994
0.75	y=-0.012x+8.319	0.998
1	y=-0.014x+8.559	0.994

表2 Kondo公式预测误差 (%)

Table 2 Prediction errors of the Kondo’s correlation

T₀/K	掺氢比 $x H 2$
T₀/K	0	0.25	0.5	0.75	1
323	1.81	0.64	2.39	3.67	0.51
348	1.64	1.09	9.40	7.67	3.31
373	1.46	2.90	11.09	10.80	2.11
398	0.21	3.67	17.66	14.25	5.65
423	1.09	8.98	22.22	18.06	12.18

表2 Kondo公式预测误差 (%)

Table 2 Prediction errors of the Kondo’s correlation

T₀/K	掺氢比 $x H 2$
T₀/K	0	0.25	0.5	0.75	1
323	1.81	0.64	2.39	3.67	0.51
348	1.64	1.09	9.40	7.67	3.31
373	1.46	2.90	11.09	10.80	2.11
398	0.21	3.67	17.66	14.25	5.65
423	1.09	8.98	22.22	18.06	12.18

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