多孔-自由火焰燃烧的实验与数值模拟研究  

Experimental and Numerical Investigation of the Porous-free Flame Combustion

作　　者：曹静宇 杨富鑫 赵旭 谭厚章[1] CAO Jingyu;YANG Fuxin;ZHAO Xu;TAN Houzhang(Key Laboratory of Thermo-fluid Science and Engineering,Ministry of Education(School of Energy and Power Engineering,Xi’an Jiaotong University),Xi’an 710049,Shaanxi Province,China)

机构地区：[1]热流科学与工程教育部重点实验室(西安交通大学能源与动力工程学院),陕西省西安市710049

出　　处：《中国电机工程学报》2024年第21期8531-8543,I0017,共14页PROCEEDINGS OF THE CHINESE SOCIETY FOR ELECTRICAL ENGINEERING

基　　金：国家自然科学基金项目(51976166);佛山市重点领域“揭榜挂帅”科技攻关专项(2120001009066)。

摘　　要：为拓宽传统多孔介质燃烧器(conventional porous burner,CPB)的贫燃极限,进一步降低污染物排放,该文设计泡沫镍金属多孔-自由火焰燃烧器(porous-free flame burner,PFFB),实验研究其燃烧及污染物排放特性;建立同尺寸二维模型,数值研究多孔介质材料开孔率、相对高度和比孔密度对火焰状态、温度分布以及污染物排放规律的影响。结果表明:相比CPB,PFFB具有更宽的稳燃范围,开孔率1%的PFFB稳燃当量比为0.50~0.67,贫燃极限当量比可达到0.45。开孔率对CO影响较小,CO排放最低为19.2mg/m^(3)。对于NO_(x)排放,开孔率4%的PFFB降氮效果最好,比CPB减少了9.3%。多孔介质相对高度对PFFB的污染物排放影响显著。在实验工况下,相对高度2/3的PFFB相比1/3,其CO排放减少了5.2~140mg/m^(3),但NO_(x)排放量增加了4.3~9.2mg/m^(3)。对于开孔率4%的PFFB,随着比孔密度的增大,孔密度增大,孔隙直径缩小,燃烧呈浸没&自由火焰,CO排放量减少,NO_(x)排放量随气体最高温度增加而增加。因此,在一定的开孔特征下,PFFB可保留CPB的燃烧性能,并且具有更宽的稳燃范围、更低的贫燃极限以及更低的污染物排放水平。To broaden the lean combustion limit of the conventional porous burner(CPB)and further reduce the pollutants,a foam nickel metal porous-free flame burner(PFFB)is designed and experimentally studied for the combustion characteristics and the pollutant emissions.A same-size two-dimensional model is developed to numerically investigate the effects of the fractional hole area,relative height,and specific porosity on the flame,the temperature profile and the pollutant emissions.The results indicate that compared with CPB,PFFB performs a broader flame stability limit,with the stable combustion equivalence ratio of 0.50~0.67 for 1%of the fractional hole area,and the lean limit combustion equivalence ratio extends to 0.45.The fractional hole area has a relatively minor impact on the CO emission,reaching a minimum of 19.2 mg/m^(3).For NOx emission,the best denitrification effect is obtained at 4%of the fractional hole area(PFFB).Compared with CPB atφ=0.59,the NOx emission is reduced by 9.3%.The relative height of porous media significantly influences the pollutant emissions on PFFB.Under the experimental conditions,the relative height of 2/3 PFFB presents a reduction in CO emission by 5.2~140 mg/m^(3) compared with the relative height of 1/3,while NO_(x) emission increases by 4.3~9.2 mg/m^(3).For PFFB at 4%of the fractional hole area,with the increase of specific porosity and porosity and the decrease of the pore diameter,an immersed and free flame is detected with the decrease of CO emission and the increase of NOx emission.Therefore,under specific pore characteristics,PFFB preserves the combustion performance of CPB while performing a broader flame stability limit,lower lean limit,and reducing the pollutant emissions.

关 键 词：多孔介质燃烧 多孔-自由火焰 低氮燃烧技术 火焰状态 数值模拟 

分 类 号：TK16[动力工程及工程热物理—热能工程]