Experimental studies on the heating performance and emission characteristics of a W-shaped regenerative radiant tube burner

In this work, the experiments were conducted to investigate the performance of a W-shaped regenerative radiant tube burner (RRTB). The effects of structure scheme of air vents in the second stage, air flow rate ratio between two stages and switching time were experimentally studied on the performance of the RRTB. It is found that the RRTB has a better performance of heat recovery. The tube wall temperature is symmetrically distributed along the tube's length, with an M-shaped profile and good temperature uniformity. The structure schemes of air vents have a significant influence on the performance of the RRTB, including the combustion organization and NOx emission. The air flow rate ratio between two stages has an evident effect on the combustion flame length inside RRTB, the wall temperature profile, the preheated air temperature and exhaust gas temperature, and NOx emission. Changing switching time has some effect on the tube wall temperature profile, preheated air temperature and heat recovery efficiency.