Study of a new type of radiant tube based on the traditional M-type structure

In this paper, an M-type radiant tube was designed first, and then based on the traditional M-type structure, a new type of radiant tube was designed with a subsonic burner and flue gas reflux channel to improve the overall performance. A three-dimensional finite element model was established, and the corresponding experimental verification was conducted to guarantee the model's accuracy. The gas flow, heat transfer and combustion characteristics of the two types of radiant tubes were compared. The results show that the speed of the flue gas in the new type of radiant tube was about 5.55 times that of the traditional M-type radiant tube because of the self-circulating gas structure. The local high-temperature zone of the combustion flame was greatly reduced in the double-A-type radiant tube, and the gas temperature gradient was relatively small compared with the M-type radiant tube, which protected the tube surface from being burned through, and from oxidation and carburization. The gas circulation rate in the M-type radiant-tube structure was 4.42, which effectively improved the uniformity of the surface temperature and the heat flux.