基于CFD双a型燃气辐射管燃烧的传热特性

Heat transfer characteristic of double-a type gas fried radiant tube by CFD simulation

运用亚音速烧嘴技术和烟气循环技术，设计了一种烟气高循环倍率的新型双a型辐射管，采用涡耗散燃烧模型和离散坐标辐射模型计算其燃烧传热过程。结果表明：42.6％的CH4在烧嘴内燃烧，57.4％的CH4在辐射管中心管内长度为800mm、直径为40mm的区域内燃烧；辐射管中心管内，循环烟气使火焰和气体等温线呈“椭圆型”分布，三通管和支管内，流动惯性使气体等温线呈“偏心圆”分布；双a型辐射管热效率为70.8％，壁面最高温度1065℃，最大温差79℃，中心管壁周向温差0～21℃，三通管及支管管壁周向温差0～15℃，整个辐射管管壁径向温差0～2.5℃。

Combustion and heat transfer in double -a radiant tube （RT） were studied by Computa-tional Fluid Dynamics （CFD） in 3D condition.The Eddy-Dissipation combustion model and Discrete Ordinates radiation model were used in the simulation .The designed double -a RT is equipped with flue gas circulation tube and subsonic speed burner .The results show that the 42.6% of CH4 burned in the region diameter of 50mm in the burner, 57.4%of CH4 burned in the center tube with the length 800mm, diameter of 40mm.The flame shape and gas isotherm in the center tube is “elliptically dis-tributed” as a result of gas circulation.The gas isotherm in branch tube is “Eccentric circle distribu-ted” due to gas inertia.The efficiency of double a radiant tube is 70.8% with the maximum surface temperature of 1065℃and maximum temperature difference of 79℃.The circumferential temperature difference in center and branch tube surface is 0~21℃and 0~15℃respectively.The radial temper-ature difference in the tube surface is 0~2.5℃.