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作 者:曹天赐 CAO Tianci(Huahui(Beijing)Energy Co.,Ltd.,Beijing 100076,China)
出 处:《区域供热》2025年第2期34-42,共9页District Heating
摘 要:过剩空气系数是影响燃气壁挂炉燃烧特性的重要热工参数之一。利用Fluent软件,对某型号家用燃气壁挂炉在α为1.4、1.6、1.8、2.0这4种过剩空气系数下燃烧室内的燃烧过程进行数值模拟,掌握燃烧室内温度场、CO浓度场、NO_(x)浓度场的分布情况和变化情况,分析改变过剩空气系数对燃气壁挂炉燃烧特性的影响。研究结果表明:随着过剩空气系数的逐渐增加,高温烟气与热交换器中的水之间的传热能力受到了削弱,燃烧室内的温度逐渐降低,壁挂炉的热效率尽管在此过程中有所降低,但仍能处于较高水平;在同一过剩空气系数下,CO的质量分数随燃烧室高度的增加呈先增后减的变化趋势,增加过剩空气系数后,受燃烧室内燃烧反应区上移的影响,CO在燃烧室后半部分与氧气发生反应时减少,CO质量分数的增减速率随过剩空气系数的增加而增大,不同过剩空气系数下的CO排放量均符合国家标准;过剩空气系数的增加能使NO_(x)的浓度出现数量级上的变化,且这种变化在过剩空气系数由1.4增加到1.6时体现得最显著,在这4种过剩空气系数下,NO_(x)排放量至少能达到国家标准中的第4级排放限值。研究结果可为燃气壁挂炉的设计改进和用户使用提供参考和借鉴。The excess air coefficient is one of the important thermal parameters that affect the combustion characteristics of gas wall mounted boilers.Using Fluent software,numerical simulations are conducted on the combustion process of a certain model of household gas wall mounted boiler in the combustion chamber under four different excess air coefficients ofα=1.4,1.6,1.8,and 2.0.The distribution and changes of temperature field,CO concentration field,and NO_(x)concentration field in the combustion chamber are mastered,and the influence of changing the excess air coefficient on the combustion characteristics of the gas wall mounted boiler is analyzed.The research results indicate that as the excess air coefficient gradually increases,the heat transfer ability between high-temperature flue gas and water in the heat exchanger is weakened,and the temperature inside the combustion chamber gradually decreases.Although the thermal efficiency of the wall mounted boiler decreases during this process,it can still be at a relatively high level.At the same excess air coefficient,the mass fraction of CO shows a characteristic of first increasing and then decreasing with the increase of combustion chamber height.After increasing the excess air coefficient,due to the influence of the upward movement of the combustion reaction zone in the combustion chamber,CO decreases when reacting with oxygen in the latter half of the combustion chamber.The rate of increase or decrease in the mass fraction of CO increases with the increase of excess air coefficient.The CO emissions under different excess air coefficients all comply with national standards.The increase in excess air coefficient can cause a magnitude change in the concentration of NO_(x),and this change is most significant when the excess air coefficient increases from 1.4 to 1.6.Whenα=1.4,1.6,1.8,2.0,the NO_(x)emissions can at least reach the fourth level emission limit in the national standard.The research results can provide reference and inspiration for the design improvement a
分 类 号:TU996.7[建筑科学—供热、供燃气、通风及空调工程]
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